Sunday, July 20, 2014

Sanyo DP50747 P50747-03 repair for sound, but no image problem

Just a quick pictorial guide on an easy repairing for a Sanyo DP50747 chassis P50747-03.

The TV would start up fine with sound, but nothing on the screen.

A quick reminder before proceeding: with Sanyo TVs (as well as some others) the model alone is NOT a unique identified. There are 7 or 8 DP50747 models that I know of, specifically P50747-00 to P50747-07 and they have very different internals and very different failures.

What's discussed here does NOT apply to other versions of DP50747, but would apply to other 50'' TVs based on the Samsung plasma display used in DP50747-03 as it would come with the same sustain boards that are used in DP50747 with chassis P50747-03.

Here is the label from the back of the TV in reference here:

Sanyo DP50747 P50747-03 repair for sound, but no image problem

Taking the back cover off is a fairly straightforward task, so no details about it.

Instead here is how the TV looks without the back cover:


First we made sure that the sustain voltages are properly produced by the power supply and passed to both sustain boards. 

If Vs was out of range the power supply itself would have shut the TV and the bare fact that it was holding was sufficient indication that the problem wasn't there, but since power supply board PS-W3 is known to develop some issues we checked it nonetheless.

As expected it was there.

So then we ran a quick test on the power components and fuses on the YSUS board (which also contains the buffer register outputs) and everything checked out.

So we shifted our focus to the X-main board (aka ZSUS) and this is what we saw:



In case it is not clear there is an electrolytic capacitor with bulged and even cracked top out of which some electrolyte has spilled.

Here it is from another angle:



This is a relatively rare problem in sustain boards in our experience, but as manufacturers kept on polishing other components and ran away from the hybrid ICs used in the second and third generation plasmas it is not unlikely to start seeing more of such issues as others get phased out, much like with the power supply boards.

Anyway, when an electrolytic capacitor starts failing like that its resistance starts lowering and it often causes excessive current in the circuit where it's supposed to filter ripple , working as a low resistance load as opposed to backup energy source.

As a result, the fuse in the circuit (if there's a fuse) often times fails and that was the case here as well.

Replacing the fuse and the capacitor took care of our TV.

Hope this helps!

Monday, June 23, 2014

Sharp LC-65D93U blinking blue LED repair experience, inverter issues

A few hints for people facing a repair on Sharp LC-65D93U due to blinking power LED.

Meant to supplement the service manual and tell you a few things it doesn't (or at least not outright) and definitely not a complete guide on how to fix it.

Sharp LC-65D93U repaired by Coppell TV Repair for blue flashing LED

 

By now I forgot, but I believe we had to pull the unit out of the stand in order to take the back cover off.

Here's how it looks like on the inside, only protection of the bottom left inverter taken down:

Sharp LC-65D93U has 2 power boards and 6 inverter boards


Protection mode(s) : blinking LED and no response

Protection mode kicks in when the main board discovers something considered dangerous and shuts off the TV, locking it out.

There are two different protection modes I was able to figure out:

Fast blinking blue LED and slower blink of blue and green led simultaneously (or, more specifically, they start at the same time, but blink different number of times and report different codes).

The service manual gives good information on the various error codes reported when blue and green blink together, but does not say a lot about fast blue blinking, which is what we had: the TV would power on to a blue blinking LED and would not respond to anything whatsoever.

To get out of the protection mode, i.e. to tell the TV to attempt to start normally, do this (as per the service manual): disconnect from AC, wait until front LEDs stop blinking, then hold down the INPUT button on the side and, while holding it, press the VOLUME DOWN button (the very bottom one, I think it was  VOL DN); then, while holding both of them, connect the TV to AC power and keep on holding until you hear a relay click.


Troubleshooting hint: lots of feedback connections, module elimination approach not working

Sharp LC-65D93U is a high end TV and has lots of built-in protections and feedbacks from its various modules, which means you can't apply the classic approach of disconnecting a module to see if it prevents the TV from powering on.

Most LCD TVs would start all right if you disconnect an inverter - they'd just have dark screens - but this one won't.

You can't disconnect the T-CON board either and expect it to start with back light, but no image like most other LCDs.

The way to do it is to find the feedback signal and feed it false positive information, i.e. make it happy.


Symptom: Sharp LC-65D93U showing image for a second or two, then going back, then turning off and entering protection mode

Skipping another issue we had, we faced the above described behavior, which looked a lot like a bad inverter or bad CCFL or bad power.

But how to find which one?

First thing we did was disconnect a whole inverter, specifically the CCFLs on it, to see if it affected image.

It did, meaning we could see notable decrease of darkness in that area.

By this rude approach we found out that seeming all inverters DID work for a while, i.e. there was visible loss of brightness in the disconnected section for every of the 6 boards. We couldn't measure how much did we lose, though, so if a single lamp wasn't coming up we could not tell which one it would be.

And it wasn't even clear it was the inverters that were causing the shutdown to begin with.

Important note: the unit would NOT go into protection mode if you turn it off as soon as the display goes black. This simplifies testing when you'd need to power on the TV multiple times e.g. to find out which inverter/circuit is bad. If you  miss the moment you'd need to do the INPUT/VOL DOWN/AC POWER procedure again.


Starting up Sharp LC-65D93U without inverters (tricking the inverter feedback signal)

 The feedback from the inverters that causes the TV to shut down if they're not in place and working fine is the center BLUE wire on this connector located on INV4 (top right looking from the back):



What you need to do is pull out the middle BLUE cable and feed it 3.3V to make it happy. We did it by using a leg from a capacitor or resistor which we stuck in the blue cable's female ending and then in the 3.3V found on the BLACK wire on the connector itself:


There, if you do this (and it makes a good contact and inverters receive proper power from the power supply) it will make the main board happy even if the inverters fail due to a bad transformer or a bad CCFL or any other typical reason different from a major shortage on the power supply lines (which, if it were present, would not allow image to show up for a brief moment!).

Once we did this the TV did indeed stay on, confirming the suspicion that it was an inverter that has gone bad.

But which one of the 6?

Determining the bad inverter in  Sharp LC-65D93U and other LCD TVs
This is again nothing new and ground breaking and while rather universal is subject to some caveats and conditions which may make it not so widely applicable.

More on them later (if I remember), now for the meat: we were hoping that a lamp (and its power circuit) would not start or start and work much different from the rest.

Since CCFL lamps are powered with reasonably high voltage, high frequency AC voltage we hope to catch that voltage inductively and by comparison find which CCFL differs significantly from the rest.

We use a fairly good meter (I hear cheap Chinese meters can't really pick it up and I believe it, but I haven't tested it) - in my case a Fluke, in VAC mode, with pre-set range of 60 volts (this was useful so that it doesn't lose time to auto-adjust for the short time the inverters work) and our probes are between chassis and on wire of each inverter output going into the backlight assembly:


Polarity doesn't matter and for best reading it is important to try and get as much length of the wire in parallel to the probe's metal lead as possible.

Here's the Fluke's configuration (ignore the readings on both pictures; they were made while TV was off):
Again: AC voltage meter, pre-set range of 60V (that may depend on your device).

When the backlight activates the Fluke picked up voltage of anywhere between 8V and 15V depending on the lead/cable configuration (angle of placement, how much length in parallel they had etc.).

The voltage was there for a very brief time and to avoid TV shutdown and protection you can turn it off (the TV, not the Fluke) with the power button as soon as you get a reading.

On ONE of the boards there were NO READINGS or VERY LOW readings on one of the outputs.

After confirming the test a few times We thought we had found our bad guy.

And you should too.


Troubleshooting Sharp LC-65D93U backlight inverter

A reminder: this is not mean to cover all possible cases that could occur.

It is a free source, after all, take it or leave it, but do not criticize it :-)


Sharp LC-65D93U uses the following inverter boards:
  • RDENC2509TPZZ (INV1)
  • RDENC2510TPZZ (INV2)
  • RDENC2511TPZZ (INV3)
  • RDENC2512TPZZ (INV4)
  • RDENC2513TPZZ (INV5)
  • RDENC2514TPZZ (INV6)
(After you've identified the source of your problem you may want to first try and see if you can find a good working board through Google. It may save you time and nerves.)

As it turns out the inverters are made of TWO electrical circuits each, with THREE transformers in parallel in each circuit.

Transformers are the usual suspect in failed inverters and sure enough we spent some time on that too; I may write another article or extend this one on how to test the transformers on the boards, but I'll skip that now as the article is already getting too long.

In our case it turned out that it wasn't just ONE lamp that was not getting power for the brief moment when others were; it was THREE connectors (six lamps altogether) that were having the problem - every other on the faulty board.



We reasoned that if a single CCFL lamp was bad (or a connection to it) then it wouldn't affect the other two transformers circuits (the other two transformers) or if a transformer was bad, then unless it was bad in the primary winding it would also not affect the other two for the short time when everything worked and the output voltage would be picked up after the other two inverters.

I can't say with certainty how much of that reasoning is true - I am software developer by heart and just hacking my way into the hardware world - but I'd say that you should test the other transformers' outputs too.

If a single transformer output is lacking output then you have bad transformer or bad CCFL.

If all 3 are missing then it's got to be something BEFORE the transformers.

TO make long story short again, we've had TWO separate problems:

One was a 10 ohm resistor found in the gate of one of the driver transistors found in 2 pairs on each board.
The resistor has simply opened and the transistors could not drive the transformers.
Replacing the resistor made the board work.

The other (which we sort of caused while testing, i.e. after we got the TV to work reliably and started testing other boards on it) was one of the SOT-23 (or similar) transistors found in 2 pairs of 3 transistors (i.e. 2 groups of 6 transistors, 3 and 3 of a kind), which was lacking base/collector or base/emitter junction resistance as expected.
As of right now I do not remember what they were and I did not take pictures, unfortunately, but that's what it turned out being.

Again, that doesn't mean it can't be a transformer in your case.

As a result of our efforts we have some transformers available for purchase.

Check at www.coppelltvrepair.com or our eBay store.

Hope this helped. If it did please leave us positive feedback somewhere on the Web...we'd appreciate it!

Good luck!

Saturday, June 14, 2014

Notes on testing Y-Main LJ41-04516A and any other Y-Main sustain


We often receive a question similar to this:
(it was sent via our eBay listing for Samsung LJ41-04516A test and repair service)

Question: "Hello, I would like to know if I have a bad Y-main board, I have tested Q5004, Q5005 Q5006 Q5007 Q5012 Q5013 Q5027 Q5028 Q5029 Q5030 are good.

Does it mean the other board is defective instead of Y- main board?"


Answer:
This answer is valid for pretty much any other sustain board I am aware of ... as well as any other electronic module which can not be (easily) tested in standalone mode, but only as part of a set made of several modules working together.

You can't tell if a module - Y-Main LJ41-04516A in this case - is working fine just by NOT finding a problem on it.

It is first because of the simple reason that you have not checked every single component on it and you can't be certain that they all work and second because you may have tested all of them individually (hardly, but theoretically possible), but you haven't tested them under load and that still leaves quite a good possibility for some of them NOT working.

The most (and for practical reasons the ONLY) reliable way to know if a sustain board is working is to to put it in a working set and see it function properly.

It is theoretically possible that you may put a sustain in a set without , say, a display (or with disconnected buffers) and measure the outputs of the sustain with a multimeter or, better yet, a scope. That gets close, but in reality is still far enough from seeing actual good image on a plasma display.

A lot of experience with a particular board - like we have with the boards we offer repair services for - can, to a degree, work as a substitute to testing on a real set, but for the same quoted first reason above it can't be a full, guaranteed substitute.

We only offer repair services for sustain boards that we can test and see working on a set.

Note that the opposite test is more applicable and beneficial: if you do find a failed component on a board (specifically one that you know tends to fail) by means of testing then you do not really need to test the board in a set. It is bad.

But the only practically certain way to know if a sustain board is good is to test it in a live, known working set.


The alternative is undefined and unprofessional.

By chance, during our recent move into our new location, we lost the testing unit for that same sustain board, LJ41-04516A. We instantly increased prices of all listings to a practically prohibitive level and told all customers who had already submitted a board that we are unable to provide a proper service and have to cancel it.


 

Wednesday, June 4, 2014

Coppell TV Repair LLC has new address, USPS inbound delays

Update June 04, 15:30 PM: Just received a call from the local mailman. He has been receiving parcels for us for the past few days, but he was not aware we have already moved in and he has been passing by our building. Eventually he realized there's too many packages and has found my phone which I gave to him when we met shortly after I bought the building.


This must have been the culprit of the delay and I am told we should be receiving close to 20 packages tomorrow.
In the last week of May 2014 we moved our shop from a location we were leasing for the past 3 years to a building we practically own.

The new address is available on the website and we've been working to update it on popular Internet repositories as well, so far without success. There's always delay in those things unless you're willing to pony up $300 or so quarterly or something like that.

Anyhow, here's the focus of this post: for reasons unexplained there is a delay in processing packages sent to us via USPS. We are simply not receiving them yet.

If you sent us modules and they were supposed to be delivered to our old Belt Line Rd., TX 75006  address on May 30th, May 31st and the first days of June there will be an extra time due to the packages being first delivered to the local postal office and THEN forwarded to our new address at W Hebron Pkwy, TX 75010.

I was told that forwarding should have kicked in and packages sent later would be forwarded before a delivery attempt to the old address is made first.

The forwarding of some packages, however, will occur only AFTER they reach the local USPS facility and a local delivery attempt is made.

I guess it has something to do with the date of forward activation kicking in.

Your online tracking information may look like this:


I was at the local USPS office today and they assured me that even though the message says that the package is being returned, it is actually being re-routed.

I do not know yet if this is true; we will know when we either start receiving the packages or customers start receiving them back.

It is hard to say why all this headache when we told local mailmen to just drop off packages at the next suite as they have been doing if by chance they happened to arrive and find the shop closed (like every Saturday).

They would either 1) Attempt delivery on the next day; or 2) Leave a note and hold parcels until we go to pick them up; or 3) just leave parcels at the next suite.

In this case we've filed a forward request, told local mailmen we want them to leave packages in next suite and left a message asking them to do the same.

For a few days we've been picking boxes from our former neighbor, but it was only UPS and FedEx.

Then yesterday there was nothing there anymore and we received our first deliveries from both FedEx and UPS at the new address.

USPS is still processing.

We apologize for the inconvenience to you and your customers, if you have any...but we feel we've done what we could.

Ideally all they had to do was just left them at the next suite...not sure why they didn't.

But we again apologize for the delay.




Monday, May 12, 2014

Repairing Voltec SPX EL-50580 charger level 2 for Chevy Volt & Nissan leaf

MAY 21, 2014 update: Looks like we;ve successfully repaired the charger! Will probably be offering a repair service for those boards through our main site...if you can't find it there please contact me through http://www.coppelltvrepair.com .

Introduction
OK, today's topic: dissecting and repairing Voltec EVSE charger SPX EL-50580 due to failure to show any signs of life upon connecting to 240V power.

As the internals will show you it was made by Intertek and has product number 4000982 and catalog number 22781774, input voltage of 240V AC, charging current of 15A and therefore consumed (or rather passed through) power of 3600 W:


The accent in this article would be on dissecting. If the page title has mislead you I apologize about that.
Google doesn't index long titles and repairing is the ultimate goal, so I figured I'd put it there instead.

A foreword for those not familiar with my style and attitude, e.g. from previous articles, our publicly available repair services or , in case you are married to me, personal experience:

I bravely venture into affairs such as this one, marriage and milk chocolate from unknown sources or with expired sanity period, fully aware that my body and soul may not be fully prepared for the journey. I may say or conclude things that a highly rated spiritual minds or better trained engineers may find impolite, improper or flat out testing outdated, maybe even dangerous.

I encourage others to find and listen to their inner voice and follow its advice, but refuse to be held responsible for the way they learn. As such, anything you find here and use or misuse shall be a direct result of your own guiding spirit, may a fast acting fuse be with it!


OK, legal stuff behind our back, let's get our feet wet!

 Failure symptoms of the bad EVSE charger
A friend of mine bought a crashed Ford hybrid and since it came without the charger he also bought a broken charger, which he brought to me believing that I can whisper a few quiet words to it and it shall start working.

Because that's how it usually works.

The charger my friend bought was flat out dead, no green lights, no red lights, nothing at all.

From what I later found out it must have been a little pop sound and a little smell when it failed.

Under the hood
I have never seen an electric/hybrid car charger before in my life and I had to educate myself a bit.

I'm not quite done yet, but I advise to get educated a bit too. A quick Google search for "J-1772" is an excellent start and will allow you to find articles to your knowledge level.

For moderately advanced minds I found this site to be a fair quick jump starter on what I was dealing with, even though it says nothing about this Chevy charger in particular.

OK, OK - onto dissecting.

So inside the charger you can find this board (which is already outside of the charger in the picture):


The board itself has a label saying LEAR (apparently a name in industrial electronics) ETON ET856 and 3E0SA0130 as can be seen here:


The top candidates for checking a dead power board of any type are the fuses on the input and despite their discoloration on the pictures and apparently melted casing on one of them they both tested good.

I guess I should first say that the whole board - or most of it anyway - is covered in protective layer, which makes measuring components harder as the layer needs to be scratched off. I guess it was covered for a good reason (standards and all), so be careful and make sure to cover it back once done.

I know exactly the thing you need for the purpose, it's on my desk, but for the life of me I can't remember the English word for it at the moment. I guess I need to eat more chocolate.

Also, the board on the picture has already been modified and if you are careful comparing this board with yours you may find the differences - it is the resistor R9 (47 Ohm / 5 watt wirewound) and the inductor L2 (not really sure, but my take was 10 mH based on the color code on it):


The original resistor must have once been poison green, but when I first looked at it the color was more of a dislodging gray was open.

The inductor wasn't open, but had a good burn mark and a crack:



First take at repairing the charger

Burned power resistors on the input of a TV power supply is not very uncommon so I figured it is possible that the power resistor has simply burned as a result of natural underrating and wearing over time.

I did not have an exact match at the time so I used two 22 ohm / 5 watt resistors in series (lower value, but what the heck, I was impatient plus it was half the power on each one, which was great).

The resistors burned beautifully as soon as we connected the board to 240V and I knew there was something more there than an aging resistor.

Back to dissecting
To save some time here I'll speed things up a bit.

The resistor R9 is in series with one of the two live / line wires and leads to the first of the two large black boxes in the middle of the board. The other live leads there as well, which made this black box the perfect candidate for something that would have been bad.

I did a little research on the components and found out them to be industrial level transformers with very wide input range and one or two outputs.

The models used were BPW-4-09-001 and BPS-1-09001 and both were missing in the specification catalog of the company that made them.

Which is not unusual in the TV repair business, it's more like the norm and even more the reason why we have to hack things (when disconnected from power and properly discharged, notarized will presenting the spouse an opportunity to work for money etc. necessities).

The two modules are connected in parallel  to the 240V supplied by the two lines through R9 and with my Fluke I could see there was resistance - high, but the same in both directions, which is unusual for any type of switching power supply (which what those undoubtedly were).

So I scratched and scrubbed a little, cut through some silicone sealant and eventually took the larger one out (just a hunch, could have started with the smaller one too):


The first thing I did after taking it out and finding (not surprisingly) that it's fully enclosed and sealed, was to measure the resistance between the pulled out component and the one on the board.

The board was infinite in both directions and the component out (BPW-4-09-001) was still having that strange bi-directional high resistance.

That decided its fate:




Second take at repairing the charger
Well, the pictures should be pretty self-explaining as to why I don't think this particular modle (BPW-4-09-001) is going to be repairable.

Just in case, though, here are a few:

- The burned IC in the middle is impossible to figure; it's just too badly burned and I do not have any marks on its top that would allow me to see what it is

- Even if it was visible the tracks on the board around it are burned too and I could only guess, but not be certain which goes where and when part of something that operates 240 VAC you better know which goes where

- Even if I knew which track went where the PCB on that area is so badly burned it may have (sure has) changed properties and can't be trusted as an isolator anymore.You run 240V somewhere nearby and before you know it there are sparks jumping up and down through the board and other components and a sound like a diesel truck trying to outrun an arrow train before exploding.


So the possible solutions are:

1) Obtaining a replacement module from the manufacturer or other source.
Haven't researched that yet , mostly because of a long experience being in the same situation in TV repairs.
I'd consider myself very lucky if I get a response - rejecting as it would likely be - back from the manufacturer.
99% of the time they just do not answer.
I must say to a degree I understand them - they can't possibly make the money they're looking for by selling parts individually, let alone the risks and headaches this brings to the table.

2) Replacing the component altogether with a hacked alternative
This is the direction I've taken.
First results were that the station became alive and started blinking green.
But it is still uncertain if it is charging. It was not.
Stay tuned for more details as they emerge.
Success! Ford C-MAX today charged successfully with the repaired/hacked charger shown above!
I'll update this  

3) Replacing the charging station altogether

This is also an alternative worth considering.

Prices of chargers will definitely go down from where they are today.

I am looking into obtaining or creating some at a price that makes sense, but my gut feeling is that their price drop will be so significant that the best course of action if you have a broken charger is to try to repair it for $50 to $100 rather than spend $400 only to see the cost of a new one be that same $50 to $100 in a year.

Time will tell.

Tuesday, April 22, 2014

Philips 42PFP5332D/37 dead, power clicking on and off

Today I've seen something that I do not think I've seen once in the past 3-4 years so I decided to show it.

A power supply board SAMSUNG PS-426-PH / LJ44-00143A came in today, from a PHILIPS 42PFP5332D/37 plasma TV.

The customer had actually sent it by mistake because we do have a listing for another power supply board used in a different chassis version of the same TV model:

http://www.coppelltvrepair.com/p/217/magnavox-42mf237s37-philips-42pfp5332d37-power-supply-board-repair-service

Well the board in the above listing is NOT PS-426-PH / LJ44-00143A , but the customer went by the model number and we ended up with a board we have not worked on before.

Here is your Samsung  PS-426-PH / LJ44-00143A for Philips 42PFP5332D/37:
 (the picture is of the actual customer's board; they had their contact info written on it so I had to smudge it a little with Gimp; I am sure there are better ways to do it, but I just smudged it).

It had a blown 4A fuse (F8005 located between the two large capacitors in the middle of the board) and a quick test showed barely a few ohms resistance from the inside part of the fuse to ground - a pretty darn good reason for blowing if you ask me.

Nothing unusual so far, right?

Well, I tested the power FETs and they were good.

I tested the power driver ICs for the Va/Vs transformers (they are separate on that board) and they were also good - nothing remotely close to short.

There aren't many other power components on the other side of that fuse, honest.

After 15 minutes of finding nothing I started desoldering the primary windings connections on the transformers....still nothing.

The only really LARGE and powerful component I have not checked was the filter capacitor
C8054 (220uF/450V) , one of the two large capacitors around F8005 on the picture.


I did not check it for two reasons:

First, it didn't look bulged, worn out or anything unusual, at least from the top; it's a little tight there so it was hard to see it all, but again nothing significant.

Second, I do not remember having ever seen a large capacitor like that short out; I've seen many dry and get infinite ESR, but I haven't seen a shorted one.

Well lo and behold:

A steady low resistance on a capacitor this size and voltage was something I saw for first time in long enough to feel like first time ever.

That turned out to be what killed the fuse.

Just for the record, C8023 was visually swollen and had to be replaced and the Vs output filter capacitor was also bad although still functional. I have not taken its number, sorry, but it was 820 uF/250V and when I pulled it out it was doing the same rattling sound when I was shaking it that the bad one on the picture was doing..only it wasn't shorted.

Hope this helps someone!

Saturday, April 12, 2014

Hisense 50K360G dead with blown main board SAG7.820.5028/ROH

A week ago a customer brought in a Hisense 50K360G LED TV with the complaint of being totally dead.

At first we thought it would be the power supply, but a quick check on it showed this was not the case.

Before the pictures a few quick notes on the brand, times, politics and other important author observations almost certain not to be closely related to the issue at hand.

When I was in China last year (how many TV repair technicians can say that, eh?) my local guide was Cindy, the sales girl for our vendor partner there. Actually at the time she has already left them and they were a bit annoyed that it was exactly her who was my guide. I choose her because she offered it, I did need a guide (and you would likely need one too!) and finally I did not actually know well their new sales person, which is by rule the only person (or people) in a Chinese company that speak English. Now I know Ana better and I would not mind her being my guide next time around, of course if only she offers it.

Not really sure if both offer to guide me, but rest assured if it ever happens I'd blog about it, under a pseudonym if I must :-)

So Cindy told me that in China Hisense is a popular brand that is considered quality.
I guess kind of like MacDonald in US :-)

Looking at board design and construction I could also tell that either Hisense has been either making boards or licensing TVs to some American brands for some years or , at least, has been using the same sub-contractors to do boards for them as well known American brands.

Which kind of puts them at the same high level.

Which is all to say that I do like that I've seen from the brand. And I also liked the slim and elegant - if not ground breaking - design of the 50K360G.

Only it was dead as a brick.

Here's what we found inside:

Dang it, this is the reason why it is so cheap: there's practically nothing in there!
A good 'ole plasma TV would hardly leave enough room for dust and when you open it you'd have the good feeling that there must be millions of things that could go wrong , they all have to be checked and customer would simply have to pay for all of it...because it was big, stuffed and expensive..and not just big, empty and cheap!

Anyhow, we measured the voltages on the power supply board and they were somewhat OK.

I say "somewhat" because they aren't exactly typical for a TV. A typical TV power supply would have a standby voltage of about +5V, a power board signalling pin that wakes up the rest of the output voltages and lots of connectors and pins on them where you can measure those voltages.

On this TV there was no +5V standby, but there was a power-on pin and that is even more confusing because on standard televisions the power-on pin usually takes +2.5V to +5V (logical 1) to wake up.

On this power supply board one didn't even have +5V handy and passing what was available was against, hmm, commons sense and past experience.

What is available is 12V and 15V if memory serves me well.

Luckily the power supply board specifications are printed on the board itself - BTW another sign for a higher end manufacturer.

TO cut the story again, the power supply board indeed does provide +12V in standby mode and indeed takes +5V to activate the rest (which isn't much).

Also, just like most other LEDs, the power supply produces AC voltage for empowering a chain of LEDs as opposed to DC voltage you'd expect if you just think of LEDs.

Here's a close-up of the main board SAG7.820.5028/ROH (click to enlarge):


And here's a close-up of the top of the board that drew our interest:
 
As you can see this is a fairly well smoked component.
This is the voltage stabilizer that takes the +12V standby voltage and makes +5V out of it.

The same +5V you can use to manually engage the power supply BTW.

Here's our advice: do not try to replace it. The same thing is likely going to happen.

Modify the board to incorporate a more powerful stabilizer or send it to us and we'd do the modification.

We were able to repair the board all right, but there is no guarantee this will always be possible.

After all, when that thing fails, it may short the +12V input to the +5V output, sending the next circuits 140% power increase...and some of them may quit.

None of ours has done it, luckily, but this is what we found when we started the TV again:


Either the customer or we have broken the LCD display and now the TV has the value of my old running shoes, even without the odor!

You know what we did?

We paid the customer $150 for that TV because we weren't certain if it was us or her and we figured we can keep it and do repairs on the main board and the power supply board for people like you.

And I am not making this up.

I must say this is the first time something like that has happened. We've bought broken TVs before, of course, but frankly $150 is fairly high for a TV that will never sell.

Meaning we won't be doing it every time someone brings in a broken large screen TV :-)