Friday, December 10, 2010

If you consider buying parts from China consider this

Next time a customer complains that they received some of our ICs with bent legs I swear I'll send them here to
see some of the REAL problems when purchasing parts.

All of the below are sold to as for "new" and, if you can believe it, prices are as for "new".

After 2 didn't work right out of the box we took the freed to cut them open and then picked another two from the same box and opened them WITHOUT INSTALLING AND TRYING THEM FIRST.

I guess it is not hard to predict what the fourth IC on the image below will look like inside, is it?

Rust on ESD components, rust on pin solder connections...

Notice how the original black filling of the IC is covered with a thin layer of a gray one.

There are several take home lessons from this:

1) Buying from China is risky. And it's not because your Chinese partner necessarily wants to trick you. Those parts were received from a company we've been working with for some time with and we do not doubt their honesty.
The problem is they themselves aren't good enough to filter the bad parts that they purchase.
And because we've tried several different vendors we can say this is the common situation out there.

2) It pays for a customer to purchase parts from a company that actually uses them in its own work. If we had sold those parts to customers and we haven't had to use them ourselves we'd probably be doubting our own customers' honesty when they call back and say that apparently brand new working parts do not work.
But since we use them ourselves we act as a first line of quality assurance for customers.
When the product you're buying is not only valuable, but greatly affects the time you spend on a job it does matter to know you're getting quality stuff.

3) Next time you want to save a penny - or even a dollar - by buying directly from China consider all the headaches that a local American company saves you. Not to say all American companies are perfectly well equipped to know the difference between good and bad parts...not at all.
But it's it's still a whole lot easier to hold a company responsible in America than in China.
And frankly, if there was an American company that could offer us the parts we need at decent prices we'd sure be buying them from here!

Thursday, December 9, 2010


A company has sent us a bunch of those boards to repair and we are sharing some of our expertise on how to test and repair them.

Those supplies are used in AKAI LCT2701AD and AKAI LCT2701TD models.

(If you need Coppell TV Repair to repair your power board please first make sure it needs repair as per the below instructions and then contact us to arrange repair. From what we learned odds are good it may indeed be faulty.)

Indeed, this is apparently a poorly made power board because all of the ones that we received had been previously serviced already.

So how do you know if it works?

When connected to 110V AC through the main connector CON0 (at the lower right corner on the picture) the board is only supposed to produce 5V standby voltage. This shows up on connector CON2 which is the second white connector from the top on the left side of the board. It is between the two heat sinks and next to the order of three capacitors EC18, EC19 and EC20.

When testing the board we recommend that you disconnect all load from it, i.e. unplug all connectors except the one that feeds AC power in.

The CON2 connector has 6 pins organized in three groups of two pins like this (starting from the top):

* STB (aka PS_ON)
* +5V STB
* +5V STB

The lowest two pins is where you get the standby 5V power. You will need a digital multimeter to measure them. It is OK if reading is 10% off, i. e. anything between 4.5 and 5.5 V will do as long as it is stable.
To measure the voltage you connect one probe to either of the +5V STB pins and the other to either of the GND pins.

To activate the power supply (which is what happens when you pres the POWER ON button on your TV) you need to pass the 5V to any of the two STB pins.
We do that by simply soldering a resistor of about 100 Ohm between the two opposite pins of CON2, but you can as well just short them - in this particular case.

Once you do, the board should start making a humming noise and the rest of the voltages should show up:

CON1 has 3 sections - 3 pins for +12V, 3 pins for GROUND and the rest for +5V:
* +12V
* +12V
* +12V
* +5V

CON3 and CON4 each have half of their pins for GND and other half for +24V needed for the inverter boards.

If you get all those voltages then your power board does not need a serious servicing.


1) Probably the single most common problem with those boards are bad electrolytic capacitors. You should check and replace those regardless of whether the above test passes or fails. Bad capacitors can change board's behavior under load and can render it useless even if it passes the simple no-load test.

Electrolytic capacitors are the cylinders with shiny tops that can be seen all over the board.

Bad ones can usually be spotted by their bulged tops compared to the other, normally flat ones.

Behind the above mentioned connector CN2, for example, is a trio of capacitors that had to be replaced (or was already replaced) on any single board that we've seen. Those are EC18, EC19 and EC20.
Originally they are rated 1000 uF / 10V each.
If you need to replace them, you should replace them with 105 degrees , 1000 uF or slightly more and at least 10V rated capacitors - the higher voltage, the better (bear in mind they get larger though).

Since EC18 and EC19 work in parallel it is also completely acceptable to replace both of them with a single 2200 uF / 25V capacitor that will work better and last longer.

One one of the boards we serviced we've also had EC11 apparently bulged so we had to replace it as well.

On your board you may have yet a different one that needs to be replaced.

If you need parts, let us know and we can sell and send them to you!

2) The 5V output on CN1 (the lowest 5 pins of the connector) provides power to all the logic functions needed when the TV is working. They flow through a power transistor located at the back of the board which carries both filter and control function.

Simply said, think of it as an operating switch which has 3 connectors - input, output and a controlling (gate) connector which tells it when to activate.

That transistor is apparently badly rated because on many of the boards we received it was bypassed by simply shorting the input and output and completely ignoring the switch control input:

While rude, this solution is a cheap and efficient one if you don't see the 5V at the connector of your board , but you see them on CN2.

If both of those fail to help you, we'll be glad to try our luck diagnosing and fixing your board for $50 or so.
Just send it over!

Wednesday, November 10, 2010

MLT070AX repair problem for Polaroid 3700 / FLM-373B or Are They Crazy

I find more and more of my daily time being taken by users and technicians from all around the country who have a little question to ask.

I am new to all this, I guess it is all part of the job.

Except it pulls you away from the job!

Where was I?

Oh yes: a few days ago someone called and said that since we repair power boards MGMEET MLT186 and MLT186B then we almost certainly should be able to repair MGMEET MLT070AX used in his Polaroid 3700 (same as Polaroid FLM-373B). This on the basis of them looking very similar.

This is how MGMEET MLT070AX looks:

The caller somehow tricked us into telling him to send the board over here so we can take our chances. I am almost certain we warned him we may fail, but he put a spell on us by simply saying no we can't. Even worse, he used the spell and made us promise we'll fix it for the same price that we had listed for its smaller nephews MLT186 and MLT186B.

Well the board arrived and I am relieved to say we were able to hold our promise.

Just do not think we are proud with it OK?

And with the explanation why I am actually getting to the heart of this posting.

Oh, by the way, if you need your MLT070AX fixed feel free to contact Coppell TV Repair, before or after reading the rest of the story.

So we fixed the board for a total of $58, which was the price for which we have repair listed for MLT186 and MLT186B.

Can you guess how much was the board for sale on the free market?

The lowest I could find available was $120 before delivery! Most were $130+.

For a power board of a 37'' 720p LCD TV of insignificant brand?!


My local Craigslist offers 37'' Samsung LCD 720p for $250, a year old 37'' LCD Vizio w/ remote for $210, LG 37'' LCD for $230 and so on.

You do the math.

I guess not everyone has or uses Craigslist.

But then again holidays are coming.

And would advise any customer to NOT pay more than $70-$80 for having their board repaired or replaced OR, when that doesn't work (because there are times when it doesn't) to keep the money and apply them towards the purchase of a new TV.

Prices are sure to go down, at least this holiday season and likely in the near future:

Monday, November 1, 2010

Power board MLT186B from ILO-32HD - how to test

Coppell TV Repair services MLT186B from ILO-32HD and as with many other services we sometimes receive boards that are actually functional.

This post should help both those who wonder if their ILO-32HD is dead because of the power board or the main board as well as those who receive a serviced power board from us and think it was not properly serviced.

MLT186B is relatively simple power board , producing one standby always on output voltage of 5V (can be a bit more without load, it's OK) and, upon instruction from the main board, activates the actual driving voltages of +5V, +12V and +24V.

(Note: a similar article for power board MLT186 can be found here.)

One uncommon thing about it is that the input AC voltage is supplied through an external button switch. Unlike most other power boards we've seen there are actually TWO connectors for AC input - one for the main input and another one, which takes the power from the main input, routes it through a button and returns it back to the board. For testing purposes this can all be circumvented by directly passing power to the appropriate return pins.

Below are two pictures with diagrams that should help you test your board.

The hardest part will probably be the connection between the 5V standby and the PWR_ON pins.
Probably the easiest way to do it is to use a resistor and stuck its pins in the connectors that are already in the power board. Unfortunately you'd need to jump to the nearest RadioShack or buy such a resistor from us or another place. It is also possible to directly short the pins, but we advise against that practice in general. Always use resistor as you never know how smart and protective were the people who designed the board in the first place!

Monday, October 25, 2010

LJ92-01200A / LJ41-02759A - the truth according to me (feat. LJ92-01203A / LJ41-02761A and LJ92-01202A / LJ41-02760A with 6 ICs)

(December 2012 update: a set of replacement Y-Main and two brand new, OEM buffers is now available at our store for an exchange service. Still, please read the article before proceeding there!

(February 2013 update: our store now has listings for both the upper buffer LJ92-01202A and lower buffer LJ92-01203A - used, but tested and functional, offerred as-is; make sure you read this article and offer description before buying!)
I've been planning to post this for a long time, but various things have been stopping me until today.

This article summarizes some of my experience with the infamous Samsung 42'' plasma trio of boards:
1) The Y Main sustain LJ92-01200A / LJ41-02759A
2) The upper and lower buffer boards  LJ92-01203A / LJ41-02761A and LJ92-01202A / LJ41-02760A

(Note: this article is about the A1, A2, A3, A4 and A5 revisions manufactured in 2006/2007. In 2010 Samsung has released new versions of those boards with four instead of six buffer ICs. It is far too early to know if they have the same flaws as the old ones. They have, for example, apparently different design and implementation and newer ICs may be better than the older SN755867 and SN755870.)

We at Coppell TV Repair often receive questions about those.

Do we repair buffer boards?
How much would it cost to have all 3 replaced?
Do we mind sharing what goes bad on the Y-Main? (this is usually from other technicians)
Are the new buffers better?
Should the customer invest in repair or junk the whole TV?

Some of those questions do not have simple straightforward answers.

I really wish it was that easy. But it isn't, not unless you want to take the king's approach to it and replace everything. Which, as reality shows, tends to be rather expensive exercise.

I truly believe that one of the humanity's major flaws is that it often tries to fix something without understanding what actually had been broken in the first place. Stepping more on the gas instead of releasing the hand brake , treating kids for ADD instead of spending more time with them or taking pills for depression instead of stopping to listen and watch to the media reporting rapes, kills, recession and end of the world in general....just a few from the top of my head.

Sorry, got carried away.

I want to tell you what happens and how it happens.

Don't forget, it is all according to me and although I have a graduate in electronics I am much better in software than hardware.
Some of my guesses may be wrong...if you catch one I'd appreciate bringing it to my attention.

Let's start with


There are two possible problems here: when a buffer fails without shorting and when a buffer fails completely.

When a buffer fails without shorting it typically results in horizontal pink/purple lines. They can appear at isolated portions of the screen or on the whole screen.

Such horizontal lines of pink / red sparkles is clearly a buffer on its way out. To see it full screen just click on an image. (screen shots submitted by customer Jason Stubbs , a man with a good taste :-)):

This problem can NOT be  detected with a meter or at least I do not know how, but as I said above if you see those lines you your buffers need to be replaced.

What if only the upper/lower half of the screen has those? Well, read on as to why it happens and you'll understand.

The SECOND, ultimate and actually more popular buffer failure is shortage.

While the pink lines described above is only a partial failure which damages the control logic in the buffer ICs, but still doesn't completely kill them this one does.

A full failure is caused by a more massive meltdown in the IC during shortage and usually results in a an electrical shortage between the power lines of the buffer.

(If you want to check if your buffer is shorted use the technique described in an earlier post.)

A burned buffer usually takes the sustain down and since both buffers are on the same power track without separation one failed buffer usually damages the other one as well.

But why does it all happen in the first place?

Because electronics wears out.


I have two theories on what exactly is wearing out more: one is the semiconductor  junctions inside the buffer board ICs are wearing out because of the temperature differences between state at rest and state at work: when they work they get hot, the matter expands and changes structure, even by a tiny little bit, then when it cools off it shrinks and the little change remains. Over time, a micro-space develops as a defect in the semiconductor junction which one day leads to a shortage.

The other theory is that the insulation material they use for covering the IC pins changes properties over time, allowing for a high-voltage spark to jump from one pin to another, i.e. from a high-voltage output to a low-voltage power supply or control pin.

Over time I started leaning more towards the first theory as the same thing tends to happen in other components that do not have silicon insulation over their pins.

Each theory might be wrong, of course, but both are too good to explain what happens to ignore :-)

So the IC burns, melts and shorts.

That causes a momentarily overload to the Y sustain board which also burns one or more output components.

Finally, since the two buffers share common data and power line without separation any high-voltage jumping to the shared low-voltage power or data tracks tends to damage whatever it finds there that is not designed to handle it. Imagine placing 120V on a 5V data line....what do you expect?!

Which means that whenever a buffer shorts, usually all three boards end up being damaged!

The second buffer is not always shorted. Sometimes - in fact most of the times - it looks like normal, but will burn upon its first run in real condition.

Conclusion 1? When a failure is caused by a burned buffer LJ92-01202A or LJ92-01203A it is best to replace BOTH buffers.

Doesn't sound convincing? Well lets then empower the real heavy artillery, something very simple we almost said it plain, but you missed it:

Buffers wear out! Literally.

If our explanation is right and the silicone insulation on the buffers wears out due to the high temperature....until one of the buffers doesn't hold any much longer do you think the other buffer will be able to carry on?

Think of it this way: if say the front two tires on your car wear out to a point where one of them tears out while driving...will you replace only that tire? And why?

Knowing that the failure of one buffer carries high risks of taking down the other...and knowing the buffer prices (which are anything but low) it's a no-brainer!

REINFORCED CONCLUSION 1: When a failure is caused by a burned LJ92-01202A or LJ92-01203A buffer it is BEST to replace BOTH buffers.
 Note: Sometimes the buffer defects in a way that does not immediately result in a complete short, but rather in a visual defect represented by pink / red sparkles in horizontal lines on the screen that vary from 1/6 of the display to the full display. When it is on the full display this can also be confused with another popular problem which has nothing to do with the buffers, but rather the Y sustain board.

Note 2: Buffer boards can be repaired sometimes, however most of the time it doesn't make practical sense for the very same reason for which it is best to replace both buffers when one dies: all ICs on the buffer board have been wearing out together and replacing one or two of them at a time, while fixing the problem temporarily, does nothing to prevent the soon-expected failure from another IC.
And replacing all 6 usually costs more than buying a new buffer.

While there is still what to be said about those buffers, we'll wrap it up for now and will switch our attention to


The same truth that holds for the buffers also holds for the sustain board  LJ92-01200A  (and in fact for all electronics) - heat wears them out.

But before we get to that we'll start with the one problem that's not caused by the Y sustain itself:

When Y Main sustain LJ92-01200A is damaged by a burned buffer
As we said earlier when a buffer shorts it usually takes down the sustain along with it.
Once damaged, the sustain may be damaged in a way such that, if you install new buffers, it will kill them on the first run.
When we say may we mean it happens. Not too often but still often enough.


Note: This is the only Y sustain failure that I know of as of the time of this writing that presents a danger to the buffer boards!

I hope I will be forgiven for not telling you how exactly to repair this failure. I'll only say there are several common scenarios and information for some if not all of them is likely available around the Net.
As I've mentioned before we know there are other technicians who monitor this blog and start competing with our services on Internet based on what they get the point.

(Frankly, no offense meant, but from my contacts in the past months with various such technicians around the country I think they don't even know most of what's in this article...but that's another story; and still those are better than the ones reading what others say and then stating it on their listings and not giving credit to their sources!)

Pay attention, though, that the sustain does not fail 100% of the times when a buffer fails. In the tens if not hundreds of boards that we've serviced I can recall two cases where we had both buffers burn, but the sustain still working.

Just a reminder that nothing that we say is set in stone :-)

Now, off to the other Y main sustain problems:


While it is bound to happen sooner or later for the same reason for which most of the plasma sustain boards designed and produced at this point in time.
People - both home DIY self-repairmen and professional technicians - often think the IC has failed when in fact it has not (it's only been a buffer failure, hehe!).

Fact: when main IC on Y SUSTAIN MAIN LJ92-01200A fails, it usually results in a blown fuse F5004.

This is the largest fuse on board located right next to the IC and above the power connector.

Another indication for the IC failure is a short between two groups of legs as shown below:


When it comes to problems this is one of the most versatile boards I've seen.
* Nearly all electrolytic capacitors bar the largest two can be seen swallowed and/or defected.
* Power stabilizers may fail, taking down other components along with them
* Output current amplifier FETs may fail (the ones under the smallest of all 3 heat sinks) possibly taking down other components along with them

Chances are I am missing some.

It's getting very late here and I think I'll stop now. I may write a follow-up or edit this article to present general conclusions.

But, in short, it helps to understand why we are asking for all three boards to move together, why most of the time we advise people to replace both buffer boards and why in the rare cases when at least one of them is working we spend a lot of time trying to educate them about the risks they're taking with replacing just one of the buffers.

Hope you understand.

And, if you're service technician, hope you link to this article!

Sunday, October 24, 2010

DELL W4201C HD powers on / off no picture - how to fix

This article describes a common problem and fix to all DELL W4201C HD plasma TVs. We've done enough such fixes to realize this is a serial defect that is going to be present in most if not all of these TVs.

5 May 2011 update: The same symptoms and solution apply to DELL W3201C, DELL W5001C and DELL W4201C!

You will benefit from doing it even if the actual problem with the TV turns out to be different (which is always possible).

If you can't do this on your own you can send the power board to Coppell TV Repair and we will do it for you for a very reasonable fee.
(or you can send it to one of the other technicians who read this blog, educate themselves and start offering the same service; we can name a few.)

Anyway, let us start with saying that the DELL W4201C is a Samsung plasma TV sold under the DELL brand.

It features the infamous trio of 1) Y sustain board LJ92-01200A / LJ41-02759A and the related two buffer boards 2) LJ41-02760A / LJ92-01202 and 3) LJ41-02761A / LJ92-01203.

This trio on its own is a source of a bunch of problems that I had touched on in previous posts and will soon summarize and expand in a new larger post.

All TVs (and there are quite a few of them) using the same trio exhibit the same symptoms, regardless of their brand. Again, that is discussed separately.

This post focuses on a specific problem commonly observed in DELL W4210C HD plasma TV and other TVs that use the same power board, specifically the PSPF651B01A /  LJ44-00110A.

Symptom: Upon powering on the TV you can hear the power board starting to work, but screen never comes up. TV may stay on or turn itself off after a short while.

Note: This symptom is very similar to the one exhibited by a dead buffer/sustain board depending on how did they burn (which can't be predicted). It is very important for you to understand that what's described here may be not what you're looking for. But it's sure very common and if it hasn't happened to your TV it will sure happen!

If your TV has been showing pink/red horizontal lines prior to dying, on parts of the screen or on the whole screen, then this post is likely not for you (even though you may still benefit from reading it).

Solution: The power board of the W3201C HD has 2 electrolytic caps that are under-rated and tend to cause problems with the basic power supply needed by the main board. When they dry too much the main board just fails to operate normally and the TV, upon initial power-on hangs in an undefined state where pretty much the only thing you can do is power it back off. Sometimes it powers off by itself after you wait enough.

To get to there you need to lay the TV down on the ground, remove its pedestal / stand and then unscrew all the bolts that hold the back cover to the main chassis. There are two types of such bolts and there are a lot of them. Other than their quantity, though, it shouldn't be hard to do it.

Here is what you will see after you remove the back cover:

The power board is the large green board with many heat sinks and transformers in the upper half of the TV. You can unplug all connectors (no need to remember which is goes where - can't confuse them) likely except the one in the middle bottom part.
To unplug that one you'll need to carefully unscrew all the bolts holding the board in place and pull the board upwards a bit. I strongly recommend using a magnetic screwdriver so that you don't end up chasing screws around the TV body. This is dangerous and may hurt.

What you're looking for is a pair (or more) of capacitors in the highlighted area that have swollen / bulged tops.

The swollen / bulged capacitors are a common visual, but not ultimate indication of bad caps. If yours aren't bulged they may still be bad and even if they're not we still recommend replacing them because it is only a matter of time before they turn bad unless they have already been replaced with others with higher voltage rating.

We will not put the information for the caps needed here because we know there are technicians monitoring this blog and copying the ideas and know-how from it. Besides, if you get to there you'll know what you're looking for.

At this point you have several possible options:
1) You can identify and find the replacement capacitors needed by yourself. Make sure you get caps that have same capacity as the original, same or (preferably) higher voltage than the original and same or higher maximal operating temperature (105 degrees should be good).

Be advised that space is tight there and it'll be difficult (and more expensive!) to fit in caps with higher voltage rating simply because they will not fit in place.

2) You can save some time and thank us for writing up this blog by purchasing the capacitors from Coppell TV Repair. They'll be shipped within 1 business day via USPS first class mail.

3) If you think you can't do the replacement yourself you can send us the whole power board and we'll do the replacement for you for a very reasonable flat rate. Contact us for details, the first of which is make sure to package the board very well!

Wednesday, October 20, 2010

Note to all customers requesting exchange before their board has arrived for service

It is hard to please everyone.

Wait, I take that back.

It is impossible to please everyone.

Customers who send in boards for repair frequently email us after purchase asking that we send them already serviced boards back before their arrive. Some of them want it because they want to watch the Sunday game others want it because they have customers on their own who want to watch the Sunday game.

But there's also a third kind : those who want to get rid of their trashed board and want to get a replacement before we see that it's been trashed.

This week alone I had to deal with two of these. It takes a lot of time, it is annoying and it inevitably results in recording a loss - financial and emotional.

I am not making this up. Currently there is a case escalated to eBay to resolve a claim by user aguilar35domingo against CoppellTVRepair because we did not sent them a different board than the one that they sent. It was the dirtiest board I have ever seen and if there is anything that I am sorry for it is that I took the challenge and restored it in the first place. So after restoring it, testing it and sending it back, CoppellTVRepair received positive feedback and then - guess what - an open case.

And yesterday another claim was opened by user jgul1717 complaining he hasn't received a board just yet when his own was on its way. Today the board arrived and I may post a picture of it later on, even though I am not sure I'll be able to catch what is needed. Long story short, someone with a VERY BIG and VERY HOT solder iron has re-soldered most joints under the board, resulting in a complete mess and several burned tracks.

Those are two cases which - for the time being - Bay counts against our TopRated rating even though we have made it very clear in the listings (and it is very untuitive) that we are not wiling to exchange good serviced boards for tempered ones.

Also this week a customer from Jersey asked that I send him a board in advance. We have spoken on the phone earlier in the week and I stated our policy, but he kept on pressing so I eventually said "OK, send me a tracking number and I'll see what I can do". I know I said that because I was very clearly aware I did not want to make a firm promise that I might not be able to fulfil.
Anyway, today customer called and was upset the board wasn't yet sent. Truth is it wasn't because I had to deal with cases practically identical with his one.

The difference is in the sender - this NJ cusomer is most likely a decent and honest person, maybe just as you are - but the case under which we operate is practically the same.

You see, we can't judge people unless we kno them very well. And, take it from me, even then when money are involved. But that's another story.

What I am trying to say is that when there is uncertainty and very objective considerations in place then the best way to go is to stick by the rules that a deal has been signed over.

That would result in slower, but more reliable business. We may lose the NJ customer because they may feel we did not make an extra leap for them. Even though I had to - and did - rush today to get the cutoff time for UPS to send their particular board so that it leaves today and not tomorrow.

If that's the way then so be it. We'll fulful the deal arrangement at least as good as it was listed and if you are unhappy then please refrain from doing a business with us for the future.

If you've already placed an order call us and if possible we will stop it and refund you.

To some long-time customers we will make exceptions, of course. And assume the risk.
Please do not be offended if  you are not considered a long time customer on your second order.
It is exceptions we are talking about here, not rules for long-time customers.

One popular and simple approach to receiving a board in advance is to pay a purchase (and not service) price for a board, then send the core in and receive credit when it arrives and passes inspection that it hasn't been tempered with.

We did that a few times and haven't had problems this far. I'd be interested to hear if you like the approach, but I can immediately point a few drawbacks:
- it requires supply of cores that can be serviced and turned into boards to sell. Not everyone will be sending in their core and not every returned core will pass the inspection
- selling full price board has disadvantages for placing in search engines

In conclusion...we are here to help you, our customer.
And even though it may seem contrary at first, keeping the rules that build the foundation of the business is more important than groing the business.

Saturday, October 16, 2010

Vertical lines / vertical strip in LG 50PC3D, 50PX1D, 50PC1DR, Vizio P50HDM, P50HDTV20A and others - defective YSUS buffers 6870QDC004A and 6870QDC005A

This article applies to a wide number of 50'' plasma TVs utilizing LG plasma panels and sustain boards like 6871QDH088A / 6870QYC004A , 6871QYH039B, 6871QZH044B, 6871QDH089A / 6870QYC104A and the likes.

In fact, many of what is said here applies to pretty much all plasma TVs made as of 2011. The principles are the same and you can easily transfer the knowledge applied here to a different model.

We at Coppell TV Repair service a lot of plasma sustain and buffer boards.

In my opinion there is a lot to be said about servicing them properly (as I have mentioned in a previous article), but today I want to focus on the 6870QDC004A and 6870QDC005A and one of the most common issues we see with them and the different TVs in which they are used.

Buffer board(s) sit on the left side of the main Y sustain board, which sits on the left side of the TV if you look from the back.

In our case there are two buffers, called upper and lower buffer, responsible respectively for setting the line pixels in the upper and lower half of the display.

Sometimes we receive calls from angry customers who, after installing the Y or even Z sustain boards that we return after service, find out that the TV screen is nothing but a strip of one or more vertical lines. Like this:

Or, if a signal is present to the TV, like this:

"Your board does not work", they proclaim, "and I want to know what do you intend to do about it!"

I wish we could really do something particular about it!
If I had the power I'd turn those customers to exclamation marks right on the spot!

Long story short, this is a typical result when a buffer board has failed.

Once - out of easily hundreds of times - I have seen the same thing caused by a bad YSUS board. It was caused by a filter capacitor at the YSUS output which has decided to short, but not quite completely, so board was running, but severely disturbed.

Easily 99% of the time when you have vertical bars on the screen it'll be a buffer board.

If there are two it could be either of them.

Now here's how to test them:

Probably the easiest check you can do on the boards is between the floating ground and the high voltage copper pads that contact with the Y sustain board.
A good board will have around 300 to 600 kOhm resistance one way and infinite in the other (using diode test mode):

A bad board, would typically have resistance in both directions and most of the boards that I have seen measure hundreds of Ohms in one of the directions. That's a clear sign for a bad board.

Another quick test that you can run which might want to try is checking the power FETs on the board for shorts. You can measure just one and any one of them because all three are in parallel.

What you are looking for is a standard FET test condition - diode-like effect with sufficiently high resistance in either direction. Now pay attention here that sometimes you may get a false positive: depending on the unit you have and its algorithm for detecting shots, many devices (including my Fluke!) are often signaling short when , in fact, there isn't any. It's likely the built-in protection diodes in the transistor that cause the effect, I am not sure about it, but I have more than certainly observed it in different kinds of FETs including those on the buffer boards.

The way I eliminate the false positives is as follows: first, try it both directions. If it's really short it can't be uni-directional.
Second, after testing in diode mode, switch to ohm-meter and test it there as well. The ohm-metter algorithm is different and usually doesn't trigger.

Usually only one of the buffers burns at a time and does not affect other boards in the TV.
It's OK to replace or repair only that buffer.

As of the date of this writing a replacement used buffer can be found for about $35-$40 delivered to you. Sure time will change that, but not very clear in which direction.

Just make sure you buy from someone reliable who will either sell you a buffer they know is good (by reading this) or ready to offer you warranty about it.

Someone like Coppell TV Repair :-)

So here are your options:

1) Seek to replace the burned FET (or better, yet, all three FETs) on the board
  • Check Coppell TV Repair store for 6871QDH088A / 6871QDH089 repair kit

    Note all three FETs are connected in parallel and you can't tell which one is shorted until you actually fetch it and try it individually.

    I should also mention that the Fluke I use is sometimes tricked by the FETs and led to believe they are short when they aren't. I test in diode mode and am used to checking for continuity in each direction at least two times before taking off a component.

    Before you buy the kit you may also want to be sure that you do not have a burned IC on the board. Repeat the test described above AFTER you remove the suspected FET. You may even want to remove all 3 FETs (and then replace all three of them) to see if the resistance measured will restore.

    If it doesn't then you have a burned IC in addition to a burned FET.

2) Replace the whole buffer board

3) Replace burned ICs on the board
  • Check Coppell TV Repair store for SN755866 plasma output register IC

    I would not recommend that for someone who hasn't tried a few times.

    If you are dying to get into it that's OK, but consider the high probability of having a few failures before you start doing it right.

    The proper replacement of TQFP-64 and TQFP-100 ICs is beyond the scope of this article.

Tuesday, October 12, 2010

Fix for furnace fan not blowing, Carrier 350MAV 58MSA with 325878-751 / HK42FZ009 HK42FZ008

If I haven't been posting lots of TV repair hints lately it's because I've been busy fixing TVs or cars or , as of the last two days, HVACs.

As Terry Pratchett puts in in one of his brilliant books, the price for being the best is that you have to be the best. Modesty is behind getting the job done. (that is from me, not Terry Pratchett)

OK, down to business. Based on what I found I expect this to be a common problem with Carrier home AC systems and I hope this will help others in my position save time and money.

Problem likely affects all Carrier furnace located control boards 325878-751 - models HK42FZ004, HK42FZ007, HK42FZ008, HK42FZ009, HK42FZ011, HK42FZ016.

Those are used in HVAC system models 340MAV, 345MAV, 350MAV, 351DA, 373LAV, 376CAV, 383KAV, 393AAV, 395CAV, 480BAV, 481BAV, 490AAV, 58MCA, 58MSA, 58MXA, 58PAV, 58RAV, 58WAV, 58YAV, 58ZAV, GB1AAV, GB3AAV, PG8DAA, PG8UAA and PG9MAA.

I'll first give you the very short version and then the longer one with pictorial.

Symptom: AC control panel is on, says "COOL ON" but no air blows anywhere in the house. Same with FAN ON. Outside unit (compressor) works when the "COOL ON" is displayed on the control panel (it is normal for it to NOT work otherwise).

Problem: Burned relay solder contact on control board 325878-751.
(of course the same symptom may be caused by other problems; this is the problem that I had!)

Resolution: Clean and re-solder the contact, cover with protective coating to prevent from happening again.


So the AC turns on (cold in my case) but no air flows anywhere in the house. As with everything I started on Internet and first read this article. You may read it as well, it's a simple and useful introduction.
I tried what was suggested there - resetting the system once - before you try other things, because I remember one time in the past when I paid AC technician $100 to do just that - reset the unit. Nor do you want to try to fix something that isn't broken in the first try soft reset first!

Once I established the outside AC works and the blower doesn't - even after reset - I took a closer look at the furnace. Here is what I saw:

Notice the LED light was solid red, indicating presence of 24V to the system and no errors.

I took the cover off::

The cover switch at the upper right corner is used to automatically turn off the control board whenever the cover is taken out. You will need to use a tape to stick it in closed position and run tests, but remember that any later operations on the board better be done with the whole system turned off by this AND the main unit power switch (follow the furnace power cable to the switch).

One thing you will want to do is bring light up there in the attic as I did. Helps tremendously and pays the effort of doing it in the first minute you have it!

Let's take a closer look at the board:

On the left side you have the control/sensor connectors marked G, R, Y and W for the color of the wires that go to them. Last is the COM.

Also on this picture I am showing the board's fuse, which is worth checking before you do anything else. I mean that's what fuses are for, right?

Finally, you can look at the thick cables that go from the board to the motor. There are several of them because there are several different windings for different speeds of the motor. Only one of them is being active at a time though and they take simple 110V AC. There's a fifth (white) cable not shown in the picture, which is the common second connector.

Now, to test the fan you should tell the board to close the relay that supplies it with power. You do that by shorting G and R on the board (the door switch must be taped in and LED must be solid red when you do it):
 You should hear a relay click quickly followed by the noise of the motor in the back.

In my case, I could hear the click, but the motor never did a spin.

Now, from what I learned on Internet and what I first checked, one equally common problem that shows same symptoms is failed start capacitor on the motor. The start capacitor is located on the motor itself and looks like this:

Before doing what I describe below I actually took it out and measured it with my FLUKE. It measured what it said on the unit itself - around 10 uF, but bear in mind this is not always reliable, even with a Fluke...not to mention many of you may not have Fluke. At the end of the post I give a few useful links from pros in this business that helped me and may as well help you.

I returned the capacitor in place and I was planning on directly passing 110V to the motor to test if it will spin when I decided to first take a look at the board due to something I had read about repeatedly failed solder joint. I have seen the exact same things in other power appliances such as laser printers and some large TVs and I figured it's easier to check this than trying 110V on a motor I have never seen before.

So after disconnecting the furnace from the master switch, I released the board clamps (see the above pictures) and gently pulled the board out. There was actually one black clamp different from the others. It was was holding the board stuck to the underlying (or, since it is upside down, above-lying) plastic base.
This clamp is located at the front right side of the board and I just gently pried it out with a large screwdriver. May not be the best way to do it, but worked for me and it should for you as long as you do not apply too much power.

Once I pulled the board out I could immediately see the problem:

From here on it was very easy. Just clean with a small screwdriver or a knife, solder (with flux!) and, in my case, apply acrylic conformal coating on top of the solder to decrease chances from this happening again.
The next two pictures aren't too good to show that, but I'll add them anyway. I know Megan Fox is unlikely to ever pick me as a lead photographer for her photo sessions and if I can live with it so should you :)

I thank to the people who had posted information that helped me solve this problem without paying any extra money. The very least I can do to honer their work is to point you to it:



Wednesday, September 29, 2010

LG 50PC3D with negative image on screen after replacing YPPD-J015C on 6870QYC104C

Yesterday an email from a customer arrived and it said:: 

Dear Coppell TV Repair,
we purchased part # YPPD-J015B from your company through PayPal.
The item arrived and is defective.  Please advise how we may return this part to you for exchange or refund. 

Thank you.

Since we sell J015C and not J15B and since the mix-up of a J015C and J016B is deadly, my first guess was that they had installed J015C as a replacement of J015B and, sure enough, it would have lasted a very short time.
I wrote back explaining that we pay premium for our J015C components (and we really do!) and that we haven't had a defective one in a very long time (and indeed we haven't!) and that perhaps they confused J015B with J015C. This is a common mistake which is the reason why in the listing for the YPPD-J015C sale we have multiple warnings about the need to use C versions for both IPM modules on the sustain board.

Here's the response:
You are most certainly NOT correct in your assumptions.  The part you sent us was NOT NEW. As soon as we received it my technician pointed out that there were imprints from the screws where it was formerly fitted and pinholes on the back of the silicone seal.
I told him to go ahead and use it because we had previously bought parts from your company with no problems.
The TV did not fail as you presume but has a negative video.
I do not dispute the experience of your company or the satisfaction of your clients.  In the pas I was also a satisfied client.  However, I resent your implications that we dot not know what we are doing here. we have been successfully servicing TV's here for the past 22 years and like Coppell TV we are highly trusted and respected.
I am telling you that the part you sold us is defective and would like your cooperation to return it for exchange or refund.
Now, I am posting the response without any changes. This way you can see that someone with 22 years of experience (and, frankly, that's more than  us!) claims the part we sold them was used and defective.
 You draw your conclusions and decide if you want to purchase from us. You were warned!

For the curious minds I'd like to point out that the sustain IPMs are NOT involved in forming the color of the picture on the display. They are responsible for the high-voltage impulses that power each individual row on the plasma, but NOT with the color.
Any defect in the sustain IPM will affect typically the brightness of the entire row, in fact the entire screen.

Other parts on the board, however - and they are, of course, related to the IPM - are responsible for using the color information to 1) control the IPM timing and 2) dispatch that information to the sustain buffers.

At the moment I will not say which are those components. I will only say that they go bad often when J015C shorts and need to be checked when J015C is replaced. (BTW this also confirms customer was right about my initial guess being incorrect; they had clearly used J015C and they had observed a common problem with a failed J015C).

What has happened at the end? Well they asked for a refund or replacement and they got a refund since a replacement would not have had an effect. Since they've been in the business for 22 years and they knew the part was defective (and we knew it wasn't) we kindly asked them to send it back. In order to avoid similar conversations in future we asked them to use a different vendor. As I said we pay top dollars for those parts and believe it or not there's a shortage of components - even at the high prices we pay - and a great supply of customers.

We also predicted they will observe the same result with the next IC they use.

Now that I think about it, we didn't play it in the best possible way. We weren't quite service-oriented and instead of helping them solve their actual problem we got ambitious of proving they weren't right.

Then again what was their actual problem? It depends on where you look at it.

To me it all started with "The item arrived and is defective."
Here's my two cents: if you're a customer and you buy from supposedly respectable source (e.g. top-rated seller with a long history and lots of positive reviews) do not jump to conclusions if things don't go as you expect. 

Try "I am having a problem, can you help me please?".

I'll be the first to admit the advice applies at 100% for yours truly.

Follow-up on October 6 2010: The J015C unit did arrive last night. I was impatient to test so I stayed late , put it on a board and, sure enough, it was working. So much for jumping into conclusions!

Thursday, September 16, 2010

How to test power supply R0804-0901 from Polaroid FLM-3232 / Polaroid FLM-323B

Since we repair those power supplies (contact us for repair if you need yours repaired!) I am often asked how can it be tested if it works.

"My Polaroid just died and after some research I found that it's usually the power supply and then I found your blog and learned that CoppellTVRepair repairs it. I opened up the TV, looked at the board and I indeed have R0804-0901. There are no swollen caps or broken elements that I see...I want to use your service, but I want to know I actually need it before I pay."

That's a fair statement. To start with, only about half the time it's the power supply that goes bad. The other half it's the main board and , at least for the time being, we can't help with that...with more than the helpful information I already posted a while ago about cross-referencing main boards from Polaroid and Memorex.

So it makes a lot of sense to test the power board instead of assuming it is dead.

And here is how:

The R0804-0901 is extremely simple in regards to operation and outputs. Unlike most TV power supplies its only standby circuit produces 24V and those can be measured at any time - on or off - at connector CN3, where the first three pins are ground, the second three are +24V and the last one is used to turn on the secondary power source for the back lights:

I measure the voltage by simply feeding power to the supply and sticking the meter probes in the connector:

Most of the time, if you have 24 volts there, your power supply is good.

Now if you want to be sure that everything works, then you also need to test the secondary output, which is at connector CN2 across the board.
It is even simpler as it has 5 pins ground and 5 pins 24 volts (separate from the first ones!):

In order to do that, though, you need to turn that circuit on, which is done by connecting the PS_ON pin on the first connector (look above) to the primary +24V through a resistor. 
Anywhere 1 kOhm to 10 kOhm should do.

On the picture below I had used a simple cable from another TV to allow me to easily connect the lowest pin to some of the ones above it through a resistor.
You will likely not have such a cable handy...but then again you only care about this test if your TV powers on and off, has sound, but there is no back light.

Monday, September 13, 2010

Samsung LN-S4041D LNS4041D shuts down intermittently

Well I'm back from Europe and overloaded with work!

This post is for a trivial problem with the BN44-00134A power supply used in some Samsung LCD TVs.

Just yesterday came across a LN-S4041D TV unit. It was brought in for service with complains for intermittent shutdowns after working for a while.

Sounds familiar - many TVs would do that, very often due to puffed capacitors in their power supply boards.
(of course it is not always the case; remember, nothing is ever certain, so the next time you call a service technician please spare their day and tell them the problem you see and not what you think is causing it!)

So anyway, after taking the back off and looking at the power board this is what I saw:

An even closer look at the upper right corner revealed the following:

Did you notice the two puffed caps? They are a little harder to see on the image - I am an electronics and software engineer, after all, not a photographer - but if you know they are there you will see them even on this image.

Puffed caps like that are usually connected in parallel and usually have the same value.

In this case they were both 1000 uF / 10V .

When replacing puffed caps it is usually best to use the same value for their capacity (1000 uF in this case) and always safer to use same or, better yet, higher value for their rated voltage.

Another important property of the electrolytic capacitors is the upper temperature range they can work on. On most boards these days this is 105 degrees Celsius and I recommend using the same or higher value.

Replacing those two with a pair of 1000 uF / 16V / 105 degrees fixes the set and will keep it running for a long long time.

Maybe happily ever after.

Thursday, June 10, 2010

Gone until late August...and some useful tips

First off, sorry for not posting for so long!

Been busy with things, mostly with being too lazy to post. And maybe too jealous of  people reading my blog and figuring how to fix stuff rather than paying me for doing it.

It's a wrong thinking, I know.
In an attempt to fight with this direction of thoughts and general attitude as well as to compensate for the recent and coming period of silence I'll post a few quick answers to questions that I've been receiving a lot lately.

Second, I'm flying back to home Europe tomorrow and will be gone until August 20th. Do not expect to hear from me until then...sorry...and have fun!

Now, the promised quick QA session:
  • How to find which ICs are burned on buffer boards LJ92-01203A & LJ92-01202A?

    Quick answer: use ohm-metter in diode test mode, ground to all output pins; run probe slowly over pins and if you hear continuous beep you've found a short.

  • How to tell which of the IXTA36N30P transistors on LJ41-02759A / LJ92-01200A is shorted without having to unsolder all of them?

    Quick answer: use ohm-metter and measure drain (tab) to source and drain to gate; all drains are common and all sources are common; gates are connected through low value resistors so most drain-gate and drain-source will read mostly same and usually pretty low. However, the shorted transistor (it's typically just one) will read 10 to 100 ohm lower on drain-gate.
  •  Is it just YPPD-J015C and YPPD-J016C that typically burn on 50'' plasma sustain boards that CoppellTVRepair services?

    Quick answer: Unfortunately not. About 50% of the time there are also other components that burn.
    Alas, could not say more than that at this time.

Monday, May 3, 2010

My type of people for customers

I happen to believe there aren't bad people in this world.

There are maybe many ill people who appear as rude. Ilness easily makes the negative prevail.

There are also a lot of, well, silly people out there. People who just do not know how little they know.

Granted, I might be one of them.

And finally, there are people who may escape both of the above classifications and who I still can't get along with.

I simply call them "incompatible".

It's because despite my best efforts - and sometimes even mutual best efforts - we simply can't get along.

Over time, I had developed a sense on when I'm compatible with someone and in still a little more time I was able to distill that to a simple list of requirements.

For the sake of avoiding the waste each other's time, here's the current state of that list, in no particular order:

  • If you think everyone's trying to squeeze and cheat you, you are most certainly not my customer
  • If by 2010 you have not yet bought anything on eBay, you are not my customer
  • If you know one particular component that needs to be replaced on your board and ask me for the discounted price to replace that component for you (over courier service) you are not my customer
  • If you need to wait until your next paycheck to get enough money to send in something for repair you are not my customer
  • If you have an AOL email account you are not my customer
  • If you bought this broken TV with the idea that you could fix it and save you are not my customer 
  • If you need to ask your wife if you can send in something for repair you are not my customer

This list is incomplete, but I realize it may sound offending to someone. I had to apologize in advance.

I may be ill, badly educated or simply incompatible.

In one last effort to calm anyone who may have somehow felt offended I will add that:

  • If you are top notch scientist, world sports champion, M&A attorney or media star you are not my customer

  • If 8 out of 10 men turn after you on the street you are not my customer either

As you can see I know what I can and what I can't wish for.

So please stop calling...if Justin Timberlake can't fix a stupid TV how are you expecting him to fix YOU?!

Wednesday, April 14, 2010

How to find plasma display panel (PDP) voltage settings - ZBias, Va, Vs, V set_up etc.

Homebrew technicians and even professional technicians with lots of experience with CRT TVs, but not familiar with plasma TVs often ask me how to find the ZBias or Va or Vs voltage for the plasma they are working on.

It usually happens when they send us a Z sustain board or Y sustain board for service / exchange and we send it back with a note remidning them to adjust ZBias after the board arrives.

Everything in a plasma TV revolves around the display and plasma displays, much like computer processors, may come in with slightly different parameters, even though they'd still carry the same panel information.

So all plasma TVs , in fact all plasma panels, would have a sticker somewhere on the back of the panel , usually in the upper right corner, which indicates the data for this particular panel.

It looks like this:
(the picture is courtesy to LG electronics, one of the largest plasma panel manufactures in the world. Did you know that brands like Philips, Insignia, Vizio, Magnavox are using either LG or Philips in their plasma TV products? Yes, the core of the TV is made by very few big name PDP manufacturers!)

Hope this helps!

Customer support issues and how to resolve them

This morning I got a call and the person on the other end said: "We received one of your Y-sustain boards and man, (chuckles) it ain't gonna work this way!".

Then he explained that they received a board serviced from us - it was a Y sustain 6871QYH039A or similar - and when they powered the TV it had popped out as those sustain boards usually do.

He said he then looked at the board and he has never seen such a bad job in his 30 years of electronics servicing experience. He has, in fact, brought in other technicians and, I quote, "they had all laughed".

Now, a little note from my end before I present the question I am actually writing this about.

On my end I know the board that he received was most certainly tested before it was sent out. It was not extensively tested and I would agree that the repair technique used is not one recommended in official LG service bulletines. After all, there is only so much you get for your money.

I do claim, however, that the board was functional and that the way it was made functional is reliable enough. I have several arguments for that claim, starting with the fact that tens of other customers use such boards, even though they are not serviced by the book.

It is very much like the way my close buddy the other day replaced the lower left arm of my Volvo without following the official dealership procedure for doing it. The car still drives great and I he saved me tons of money. I am aware he used a hammer to get somethign out when he could have used a machine, but I trust his experience and I believe I made a good deal by choosing him over Volvo dealership.

Frankly, I have no idea what did the technicians laughed at. I am actually about to call back in a minute ( I was driving before ) and ask what was there to laugh at. They may want to chime in here.

I myself avoid laughing at people with 30 years experience in anything. I just wonder how come they had to rely on my service at all.

I sell the parts for the board and I make it clear everyone is welcome to try the repair themselves.

Now to the point: bad feelings aside, let's try to analyze the situation. You do a remote service job, you test your product. Customer tells you it fails on furst use. Let's assume all he says is true and he's not trying to trick me.

Let's face it, it is possible for that to happen. Unlikely, but possible. It may be due to cold solder on your end, due to malfunctioning component - be it replacement or another.

It may also be due to improper installation. Customer, of course, would rule that out in the same fashion in which I'd rule out the possibility of a tested board to blow on its first use after the test, but the fact remains - it is possible.

Sustain boards , in particular, produce sharp voltage changes resulting in all possible harmonics. Resonances are possible and it is essential that the board is well affixed to the body to avoid them.

So it could have been anyone's fault.

My question is - what would you do if you were the vendor?

What would you do if you were the customer?

Tuesday, April 6, 2010

The mysterious case of Dynex DX-L32-10A / T-Con 315WA01C

Got your attention, didn't I? :-)

315WA01C is the T-Con board used in Dynex DX-L32-10A 32'' LCD TV introduced by BestBuy about a year ago.

Here is what the board looks like:

The mysterious thing about it is that a year after the TV reklease, Google can still find only 5 (five!) refernces to that board at all!

And it's been that way for the past few months - I know because I've been looking for it.

Oddly enough, one of the few links leads to a PartSearch actual product offerring , but not unexpectedly, their asking price is comparable with the price of a new TV of same or similar cheap brand.

One thing that puzzles me is if it's the board that has gone bad or the LCD itself as some of my sources claim.

It is hard to be sure, but I first determined that the LCD supply power is there on the T-Con output - 15V and 3.3V, which, even though not a guarantee, is a good sign as far as burned T-Con boards go.

And then I played some with my fingers through the T-Con while TV was working and for a second I got - I swear - proper image in the middle of the screen!

So I'm leaning towards the probability of the T-Con gone bad.

Yet I still feel bad ponying up $75 just to try. Especially for a model that has been unofficially discontinued and apparently not supported.

If I decide to try it I'll let you know.

For the time being, just stay out of Dynex, all right?

Monday, April 5, 2010

The Polaroid / Memorex mess 200-107-GT32XA-AH, 200-107-GT32XA-BH, 200-107-PF261XA-CH and more

In March I blogged on the ability to interchange main board between Polaroid TDA-03211C and Polaroid TDX-03211C.

A few days ago I had a customer bring in a Memorex MLT3221, which, deisgn wise, appeared the same as the above mentioned Polaroid models. It was apparently the same piece of equipment just branded to a different company.

Well, almost the same.

Even though it is the faulty power boards that those Polaroids are notorious for, the Memorex MLT3221 had an apparently good power board - first because it had all the produced voltages neatly printed on the board and second because they all checked.

So apparently it was (again) the main board. 200-107-PF261XA-CH.
Presented here for your viewing pleasure:

Well, it turns out this boad is rare. Especially if you search for a board for Memorex.
In fact, I did not find any availability for Memorex.

However, I did find a board with the same tag available for Polaroid TDX-03211C.
You guessed it, it worked.

But wait, it's even more interesting! Suppose you do not find 200-107-PF261XA-CH for neither Polaroid nor Memorex. What do you do then, throw the TV out? Pay $150 for a main board for a 32'' TV when you can get a new one on Craigslist for $250 and at Walmart for $300?

No, you can simply use 200-107-GT32XA-BH from Polaroid TDX03211C and therefore, because of my earlier post, you can also use 200-107-GT32XA-AH from Polaroid TDA03211C!

And I am not kidding you, it works! I tried :-)

There might be the minor issue of having to see "Polaroid" instead of "Memorex", but if you find the board at a good price that would hardly matter a lot, right?

And finally, if you use Polaroid board in Memorex you will need a little extra work to extend the antenna cable connecting the board with the external antenna outlet.
You see, the Polaroid boards have the antenna receiver placed higher on the board and turned horizontally as can be seen here:

All in all, though, none of these is a deal breaker.

I hope you can use that information and it can serve you well as it did serve me!

And do not forget to order your parts and services from :-)

Friday, April 2, 2010

Polaroid FLM-3232 power board R0804-0901 repair service offerred

I spent some time familiarizing myself with FLM-3232 power board R0804-0901 and as a result I now offer repair service for it.

Apparently the board is prone to burning and unfortunately it's not just due to drying out filter capacitors - it involves active elements too.

If you need yours repaired you can find the service here.

UPDATE: I posted an article on how to test the board so that you do not send it for repair without having to.

Friday, March 26, 2010

How to identify burned buffer boards LJ92-01203A LJ41-02761A LJ92-01202A LJ41-02760A

(UPDATE 25 Oct 2010  - I have added another article with additional details on the subject. Find it here.)
(UPDATE Dec 2012 - now the Y-Main and a set of brand new, Samsung OEM buffers is available at our store.)
(UPDATE Feb 2013 - our store now has listings for both the upper buffer LJ92-01202A and lower buffer LJ92-01203A - used, but tested and functional, offerred as-is; make sure you read this article and offer description before buying!)

Here's a very simple and easy method of identifying burned buffer boards LJ92-01203A / LJ41-02761A  and LJ92-01202A / LJ41-02760A.
Those are the buffers for Y-sustain LJ92-01200A.

The trio is used in a great number of 42'' plasma TVs using Samsung plasma display technology (the display itself and the sustain/buffer boards).

It is also famous for its common failure. The most common scenario involves burning the Y sustain which subsequently burns one or both buffers.

Now, to the point: The most common defect in those buffers manifests itself in burning and shorting the power lines and some output lines.

The easiest way to detect if a board was burned is to measure the resistance between its power input and ground.

Normally it should be in the range of hundreds of kOhms and when burned it is usually a matter of Ohms.

In fact, you can use the diode/audio test mode to determine if a board is burned or not.

Still , in the below examples, I am using a multimeter in a standard resistance meter mode.

On the TOP buffer board, the power lines are the top two lines of the black connector and ground are the most of the remaining connectors.

On a good board the resistance between the two may be too big in the proper direction and about 500kOhm in reverse direction.

The board on this picture is good.

On the bottom board the power lines are the bottom two lines on the black board and ground is above them.

In the example picture on the right the resistance there is only 4.4 Ohm clearly identifying this board as a burnout.

The resistance would typically be the same in both directions.

This board would prevent the TV from powering on and may also burn the Y-sustain board.

In a future post I'll also show how to identify the particular ICs on the burned board.

Tuesday, March 23, 2010

Giving warranty on modules and components - pros and cons

Today I got a question: "What warranty do you give on your LJ41-02760A LJ92-01202 Repair Service?"

Warranty is one thing I have always had problems with.

Especially for electronic modules, whether new or serviced.

As I explained the potential customer, the problem is that a faulty sustain board can easily burn a buffer and it would only take a 2-3 seconds to do so. I know it the hard way myself, in fact I still have that Y-sustain waiting for service on my desk.

So how could one issue warranty to a part that can be installed and fried right on the spot?

The simple and logical answer is - one shouldn't!

Then how are customers protected?

Well, in my opinion there are two options here: one is to break the above rule and hope that people , in general, are fair. In my opinion this is how Lehman Brothers, credit crisis and socialism in Russia all started.

The second approach is to not trust people, but turst common sense instead. A customer's motivation to buy product or service is based on a balance of cost, risk and potential benefit.

Presenting or pumping up warranty lowers risk for the customer and they get ready to buy.

Since I don't want to turn to the next Lehman or the next Russia I say we don't touch warranty if we have no control over installation and use process and instead we play with the cost.

I say I offer the cost low enough to get started - even if not profiting - and then slowly building a history and recommendations. Then I increase the price so I can actually make profit.

An independant marketplace like eBay helps a lot for building credit through past sales. if a customer sees 10 other customers being happy before him he'll certainly feel more secure even if I do not offer warranty.

What is your take?

Thursday, March 4, 2010

715T2907-2 repair and/or trade-in service available

Just a quick note to announce I now offer trade-in and/or repair service for power board 715T2907-2.

This board is used in Insignia NS-LCD26-09 , Westinghouse W2613, Bush LT26M1CA and probably others.

Typical sign for the problem is TV powers on and off (responds to buttons and remote), but screen is dark.

Friday, February 26, 2010

Polaroid TDA-03211C red light, does not power on

A few days ago receive a Polaroid TDA-03211C which was powering on to red light, but refused to continue past matter what.

The power board had the main capacitor of the SMPS visually swollen and I decided to replace it, but that didn't help. It looked the power was just fine and I could measure its output.

That left the main board 200-107-GT32XA-AH REV:A as the only component to blame.

After examining the board I found nothing to suggest where the problem might be and without a schematic I would better check for replacements before starting to debug.

Well all 200-107-GT32XA-AH version on Internet had been recently sold!

eBay, ShopJimmy, Discount-Merchant - nobody had it , although reportedly all of them had it at some point, some actually rather recently.

However, I realized there was another board in circulation, the 200-107-GT321XA-BH one.

At the time of writing this it is still available for $125 on eBay from several vendors.

In my opinion, $125 for a replacement board for a 32'' TV is too expensive, but I was lucky to be able to find one vendor who was selling it at a reasonable price and I decided to bite the bullet and try it.

Long story short, it worked and the TV is now just fine.

Another happy customer.

I'd like to think the problem with the board is something minor rather than overheating and disconnection of SMD processor. If you ever find out what is going bad on that board please post it here.

Tuesday, February 16, 2010

Sony KLV-40U100M problem - dead, no picture, no sound, no power - 715T1723-J

A Sony KLV-400U100M LCD arrived in shop today with no signs of life - no LED on front panel and no response to any of the buttons whatsoever. Comletely dead.

One could hear a short buzz when plugging in outlet, though, so at least power board was showing some signs of life.

So it was either power board or main board.

Power board 715T1756-F was a bit difficult to understand without a schematic as it doesn't have any indication of what it should provide, but by looking at the back of board where the connector contacts were I was able to isolate the standby power which turned out to be 5V and available.

With a little guessing I could also figure the power on signal pin and upon signalling it with 5V through resistor I was able to bring up other voltages.

That ruled out the power board as a suspect and left the main board 715T1723-J as the prime suspect.

And indeed it was!

I'll eventually blog about what I learned as it will sure help some, but for the time being I have to go....sorry.

In the meantime, if you need your own board serviced feel free to contact me.