LG 50PG60 plasma TV not turning on, blinks four times - what is the problem and how to repair

It's been a while since I posted in the blog and it's because we are so busy with work lately.

Unlike other articles, this one will not be based on personal experience with this particular model.

It's just a question we received and my answer to it for all I know.

The logic here is fairly applicable to many other similar situations.

Question:  
LG 50PG60 TV won't cut on. The power light blinks four times and that is all it does.

Coppell TV Repair's answer:
First things first: I have to say that I have not worked on that particular TV model. 
When I do I'll revise this page to be more specific.

It would be a good thing to know if the power supply clicks when the TV gets powered on or not.

That would say if the power board is functional enough to at least recognize the power on command and process it to the point where it tells the power supply to wake up.

Here are the most likely possibilities based on experience:
1) A bad power supply board EAY43510801 failing to start up as expected

2) A bad main board fails to either wake up the power supply or continue the TV initialization process once power is generated.

3) Another failed board preventing the TV from coming up as being detected by either power or main board and causing it to signal error and shut off.

Let's quickly review the three possibilities and how do you test and eliminate each with what's handy:

1) A bad power supply board EAY43510801 failing to start up as expected  
With the note that I have not worked with this particular board, I've worked with several others that are used in brother and sister models of the LG 50PG60 and I would hazard a guess that the PSU (power supply unit) EAY43510801 can be tested fairly quickly and easily.

I won't type the details again here, but you can read one of the following articles, which explain it:

http://blog.coppelltvrepair.com/2013/09/how-to-test-lg-eay60968801-power-supply.html

http://blog.coppelltvrepair.com/2013/06/question-about-repairing-power-supply.html

http://blog.coppelltvrepair.com/2013/04/lg-50pg20-not-turning-on-is-power-board.html 

They all say basically the same thing, so it shouldn't be hard to apply to EAY43510801at all.

If the test doesn't pass you can contact us for a repair service on your EAY43510801.

Until we gain some hands-on experience with the board there won't be a listing for it, but I can tell you that we can't charge more than $70-$80 for repair for purely practical reasons. If we can't fix the board or it is too costly to fix the only thing you'd end up paying is the return shipping for the board - no parts and no labor.

2) A bad main board fails to either wake up the power supply or continue the TV initialization process once power is generated.
That can be somewhat hard to test and frankly the best thing to do is to leave that option for the last and rule out the others.

Short of hearing or seeing someone who's seen this problem multiple times and telling you what exactly to look for the best way to test a main board for an issue is to have it replaced with another.



3) Another failed board preventing the TV from coming up as being detected by either power or main board and causing it to signal error and shut off.

While this could be any board that is monitored (and the power supply board monitors most if not all of its output voltage lines) the two most likely candidates for that are the two boards that consume most power and those are the two sustain boards - the YSUS (Y-main) and ZSUS (also called X-Main).

The below instructions are only focusing on testing the YSUS and ZSUS boards. That leaves open the possibility of another board causing the failure, so do not forget about it if all tests here pass!

YSUS in 50PG60 is EBR41728701  and ZSUS is EBR50044801, but you won't need those numbers before you suspect any of them as a problem.

A sustain board can be bad in different ways and can cause different misbehavior, but specifically when TV does not come up (meaning front LED not staying in solid "on" state - blue or green or whatever indicates "on") then there is a relatively simple way to see if a sustain is in the way: disconnecting it from the power!

I instantly want to note that this is not true for all TV makes and models. Panasonic plasma TVs usually would not tolerate, but most LG based plasmas and many Samsung ones, especially older ones (I just haven't seen enough of the generations after 2009 to know) would also allow it.

So in a nutshell you just disconnect the YSUS board from the power supply and try to turn the TV on.
If the YSUS (or the buffers after it) were either shorted or just badly overloading the power supply and causing it to shut-off itself, then by removing them you remove the problem and the TV would happily come up, even without a screen.

If so then you know you have a bad YSUS and/or buffer boards.

If so you can search for EBR41728701 and possibly the buffer boards.

If no help, then you usually want to connect the YSUS back to the power and disconnect the ZSUS EBR50044801 for another try.

Disconnecting the power supply only is usually sufficient. Sometimes - rarely yet sometimes - you'd have to disconnect the data signal cable too as a damage can be showing through it and causing the shutdown.

Basically this is how far I can take you this time...testing the power and the two sustains (with some limiting conditions) as the most common sources of problems in plasma TVs.

If those quick tests don't help I'd go for a commercial advice.

Good luck!

GE GSS25LGMB compressor not working - DO NOT PANIC!

Synopsis: This article will teach you how in 15 minutes you can fix your  I fixed my GE GSS25LGMB which is melting because its compressor is not working. It will also explain why it takes 90 minutes to do a 15 minutes job. To make it more accessible and appealing to the masses it also includes a subtle reference to Hitchhiker's guide to the galaxy, which, in case you do not know, is/was/will be the best selling book ever published by the great...oh never mind!
Enjoy!

Exactly 90 minutes ago, at 11 PM on a usually busy Monday during which we received yet another truckload of TV boards to repair, it finally dawned on me during my last quick visit to the kitchen that the floor water I've been running into during the past few trips and bravely ignoring wasn't there from the usual suspects.

Everyone is asleep at this God blessed hour and I feel almost like Head Of Household. Those of you married with kids would know what I mean, the rest can just take it as a tasteless attempt at humor.

Anyway, there were water leaks to the front, right and under the fridge which left little room for confusion as to the source and when I opened the freezer door and saw the action there there was no doubt: the packs of expensive, organic and spouse purchased meat was starting to melt and I was about to get in big trouble as soon as the real Head Of Household would have the ability to assess the facts.

The symptoms: melting ice, leaking fridge, suspiciously quiet.

I knew I was onto something there with it being quiet. It's a 10+ year old GE GSS25LGMB  and lately it hasn't been overly quiet.
I could hear the fan, but nothing else.

The compressor was definitely dead.

Oh no!!!

After quickly considered my options I reasoned that:

1) Calling a tech in the morning is probably not a good idea. I've blogged before about my opinion of TV technicians who come to your house and it isn't high and it isn't any different for any other people who come to your house to work on it (lawn mowers excluded).
99% of the time they charge you tons of money for something they could have told you over the phone and have you fix by yourself.
Like I am doing here, only I'm kind of making you read through my attempts at creative writing.

2) Getting up early and catching a plane to Alaska or elsewhere then playing no consent to the rotten meat case. I knew they would eventually catch up on me though, so that was also off.

3) Going to HomeDepot or Frys and buying the first discounted fridge that would fit the bill. Brand new, after all, discounted and I'd be in and out by 10:20 AM, which, with some help from God, could actually save the meat and my head.

So I went to bed and was almost happily falling asleep when it hit me: how could I possibly buy a new refrigerator without consulting my spouse?!
And if I did how on Earth would that end up in time for the meat to be saved?!
We'd have to go to every appliance store in the greater Dallas area and find all the bargains, then research the reviews for each of the available models, weight the data, go out again, find that the model we've almost chosen is no longer available, go back home, do some more research, feed the baby, go to work, have sex argue a bit, and what not.

So I got up, got to Google and found this:
http://forum.appliancepartspros.com/refrigerator-freezer-repair/26780-gss25lgmb-bb.html

(you should note I am an honest and decent person giving credit where it's due!)
If you are lazy, here is the above article in pictures:

 

1) The label on the inside of my fridge as a proof that this story is true and correct to the best of my knowledge.

 2) The main control board AP4436216 located behind a cover in the lower right section at the back of the fridge. Taking out the plate was easy enough and fetching the board required long pliers to press a little the two plastic holders that held the board in place.

In order to get access I had to disconnect the water line from the wall, which even I could do since there was a faucet in the wall that stopped the water. With an adjustable wrench I just unscrewed the blocking bolt and the water line was off the wall in no time!

 

3) Another look at main control board AP4436216. It is sure used in other GE fridge models and it is going to have the same issue there.

4) Getting closer and closer to the problem. Can you see it from here?

 5) You MUST be able to see it now!

So long story short, I used a sharp screwdriver and cleaned the track around the burned pin.

It turned out there was actually NOTHING left around the hole so I had to scratch off the protective layer above the track for a good 5-8 millimeters, then cleaned it well, soldered it and soldered some thick wires to the hole where I soldered them to the pin of the relay.

Sorry, no picture for that...it was getting late and it's a trade secret anyway :-)

It took a total of 90 minutes, pretty much 75 of which was cleaning, pushing, emptying, turning, unscrewing and reading on Internet.

Actual job of taking out the board, finding the problem and fixing it was no more than 15 minutes.
Granted, I am handy with soldering.
You should be too, this is a TV repair blog after all!

Now, in conclusion I'll add two things:

1) I've had another article about a problem with the AC in the house failing.  Here it is:

http://blog.coppelltvrepair.com/2010/10/fix-for-furnace-fan-not-blowing-carrier.html

It is amazing how the problem is exactly the same!

It is easy to see how those problems must be all around the place and field technicians are making sweet and easy money on your back just coming to the house and charging you hundreds of dollars for something you can do in 15 minutes.

You really can, even if you have to spend another 15 minutes watching videos how to solder!

2) I've had another problem with my GE GSS25LGMB fridge lately: it would not dispense water.

After reading on Internet I found that this is a common problem caused by water freezing near the dispenser and the solution to which is to install a warmer so that the water (in the freezer) does not freeze.

Installing stuff sounded even worse than paying money for it so after some experimenting I ended up with the following simple solution, which has been rocket solid ever since I implemented it:

Pictured are the open freezer door and a piece of thermal insulation. It is attached by the widely popular and never aging system involving Scotch tape and some more Scotch tape. The material itself would have been Styrofoam if I had one handy , but I didn't so it is the stuff we use to put large ICs on to protect their pins.
Don't know what is its name, always been curious to learn, but it's also good for cushioning.
As I said the water never froze ever after put it there.

Well...it wasn't even 90 minutes and it's totally free..what more could you possibly want?!

If you're in the DFW I'd be glad to come and do it for you for a standard flat rate of $400.

Your fridge will My fridge work like new in no time!

Vizio P42HDTV10A repair - how to test for shorts

From today's mail:


Dear Coppell TV Repair,

    just got a Vizio P42hdtv10a in, it has a bad ysus board I think, how do I test for shorts?

 
This post comes at least 4 years before it should have been posted, but then again if emails keep arriving asking about it I guess it is not too late either.

Vizio P42HDTV10A is based on the same plasma display technology by LG (read: plasma display, sustain and buffer boards and main plasma logic controller which orchestrates them) as many , many other TVs from many, many other vendors.

There is a known culprit in the two sustain boards , which are practically wearable and certain to fail after so many hours of use.

To find out more just refer to a related post I've made a few years ago about troubleshooting HP PL4260N:
http://blog.coppelltvrepair.com/2011/02/hp-pl4260n-suddenly-lost-picture-how-to.html


And here are the related services that Coppell TV Repair provides:

http://www.coppelltvrepair.com/search?Q=P42HDTV10A+&As=false&Pf=&Pt=&Sid=false&btnsearch=Search

How to test LG EAY60968801 power supply board

LG EAY60968801 is used in a number of 50'' LG TVs from the PK series such as LG 50PK750-UA.

We often get asked how can the customer be certain that their EAY60968801 power supply is bad before sending it for repair.

Nobody likes wasting time and money on moving good stuff around, including us.

Well there's a REALLY simple way of testing that particular board - and many others.

We've actually already disscussed it in a past article for another similar board:

http://blog.coppelltvrepair.com/2013/04/lg-50pg20-not-turning-on-is-power-board.html

In a nutshell, if you disconnect all cables but the AC power cable and then connect to AC the board should click once and all output voltages on it, including Vs should be present.

If the board clicks once and then once more within a second or so then it is bad.

The key here is to make sure you disconnect the other cables!

And here's a link to the repair service for the board:
http://www.coppelltvrepair.com/p/500/eay60968801-eax6139250112-lg-power-supply-board-repair-service-for-dead-or-clicking-on-and-off-problem

Olevia 237-T11 power AEP016-37 testing and repair

This is a quick pictorial guide on how to test the power supply AEP016-37 found in Olevia 237-T11 and the rest Olevia models that use the same power supply board.

There is also a link to a repair kit sold by Coppell TV Repair for the commonly found bad capacitors on the board.

The AEP016-37 power supply is not labeled , but is known to fail and if your Olevia 237-T11 (or other that use it) does not want to start up it may or may not be because of the power supply in it.

One nice way to avoid spending time and money is to just test the power supply out of the box and see if it produces the necessary voltages.

All you need is a simple voltmenter and some patience.

Of course along the way you will also be on the lookout for swollen / bulged capacitors.

Here is how AEP016-37 looks:

There are four bad capacitors on that picture, but because the picture was taken directly from the top it is not possible to see the bulging. Yet you can see the electrolyte spilled on top on some of them.

If you find bulging capacitors you should replace them. They may or may not be the source of your problems, but they are easy to replace and guaranteed to cause troubles eventually, so you might as well take care of them right away.

CLICK HERE FOR THE COPPELL TV REPAIR KIT FOR AEP016-37 POWER SUPPLY

AEP016-37 does not have indication on the output connector pin layout, so I've created one for you:

Upon connecting AC power and turning on the power board with the switch located next to the AC connector only the +5V standby voltage is present.

It is measured to any of the GROUND / GND pins on any of the output connectors.

To activate the power supply you need to SHORT the pin next to it - the POWER_ON pin - with the +5V standby.

When you do that , the +5V main, the +18V and the +24V should also appear, all measured to ground.

Voila, that is all!

Good luck troubleshooting your Olevia 237-T11 or whatever other TV you have that has AEP016-37 inside!

EBR50267901 LG YSUS for ELEMENT PHD42W39US repair and exchange services now available

We were brought an Element PHD42W39US 42'' plasma which was powering on to no image.

Inside was the first case when I personally saw a plasma TV without a ZSUS (X-Main) sustain board ever and it spooked me for a while.

Turned out LG simply put both sustain modules on one board - the EBR50267901 in this case.

(I've later seen a very similar board - clearly the same design, but the ZSUS functionality was removed from it; I do not know which was later or newer, but clearly LG experimented with this one).

Oddly enough, it was exactly the ZSUS functionality that has failed and that has resulted in a dark image.

All the power FETs on the ZSUS side (heat sink HS906) were blown and in addition the little IC909 with the mysterious "1725" was also burned.

Finding out what that "1725" was proved to be a challenge.

If you need IC909 "1725" or the 45F123 power FETs you can drop me a line and I'll see what I can do.

Better yet, you may consider either sending your board for repair or buying a working EBR50267901with a cash back option upon sending your dud (without traces of previous repairs or tampering!):

DELTA DPS-250AP-34 / Sony 1-474-095-12 G2D power supply test, repair and exchange

A hotel chain sent us a number of power supply boards DELTA DPS-250AP-34 for repair and we've collected some hands-on experience repairing them.

The board is used in a number of Sony LCD TVs (37'' and 42'') and its stock Sony part number is  1-474-095-12.

TESTING PROCEDURE
Upon connecting the board to AC it produces 3.3V standby voltage on the appropriately labeled pin on the CN602 connector located in the lower right corner of the board; the pin is third from bottom to top and is labeled "STBY3.3V" and the ground to measure those to is the 3rd, 4th and 5th pin from the top, accordingly labeled "SGND".

Upon shorting the STBY3.3V pin with the POWER_ON pin (which is the lowest on the CN602) connector the board should produce a swift click and output 24V on the CN603 connector as indicated on the labels.

If it does then it is most likely good.

The two problems we have seen were lack of standby voltage and lack of response from the board when activating it.

DPS-250AP-34 SERVICE AND EXCHANGE SERVICES

SAMSUNG FP-T5084X/XAA dead, no response - repair kit for power board BN44-00175A

Just a quick note for the few owners of Samsung FP-T5084X/XAA (a.k.a. Samsung FPT5084) : the power supply in your TV has a known series of bad capacitors leading to a dead TV.

We could confirm that after we've had several units brought in for service over the course of the past month and they all had the same symptom - a totally dead TV with a very slight whining to be heard from the back (I guess not everyone might be able to hear it).

The FPT5084X/XAA would not respond to power on command from neither the standard power button nor the remote. They'd all just be totally dead.

My first thought was for a bad main board, but it turned out the same old power supply issue. In this case it was coming from power board BN44-00175A as shown below.

Here's the Samsung FP-T5084X/XAA without the back cover (click to enlarge):

And here are two of the problematic capacitors:

Given this is a Samsung plasma I'd expect problems with the Y-Main and buffer boards before anything, but in this case apparently not.

Here is a link to our store where you can get the replacement capacitors and possibly other kits and repair services for the Samsung FP-T5084X/XAA.

Question about repairing power supply board LG EAY39190301 / PSPU-J702A

Question


I am interested in the following service: REPAIR SERVICE FOR POWER SUPPLY BOARD LG EAY39190301 / PSPU-J702A

With all cables connected, tv flashes 3 blue lights then back to red. With all cables disconnected, once AC is applied to PB it clicks on then right back off. If I just disconnect the YSUS, the tv will power on with audio only, no video.

Answer
From the sound of it I would say your power board is working just fine.

As you may know most power supply boards - especially the more powerful ones, which means pretty much all plasma TV power supplies - have several modes of work, most simply categorized by how many circuits are activated to produce output power.
At the bottom is the very low power, always-on standby power supply circuit of +5V or +3.3V.

Then, through a control signal the board is often told to "wake up", which usually involves activation of the power factor correction circuit on the AC side and a bunch of circuits producing bunch of voltages on the secondary side. This is also the stage where the relays click.

And most plasma TVs have yet another stage where the most powerful output voltage - the display sustain one - is being activated and the dreaded Vs is produced.

Power boards have multiple protections built-in in them - the higher the risk - the more and more reliable the protections - and in many cases all you need to find if a plasma power board is faulty is to know if it is capable of producing this last voltage Vs. If it makes it there it's pretty much fine.

And if something gets in the way of producing Vs the power board usually shuts itself down on the way there.

What I am getting at is that the bare symptom that you have a working TV with sound is a very strong indication that your power board EAY39190301 is fine.

And since the sustain board apparently gets in the way of the TV working it's logical to conclude that this is where the problem is.

One more thing on the power boards: some of them - not most, but some - have a programmable ability to turn on all their output circuits when AC is supplied and nothing else is connected to the board.

This is very useful when testing a power board because pretty much all you need to do is pull out all connectors beside the AC power one and supply the AC. If the board clicks on and stays on (and Vs is present, in case of a plasma power supply board) then the board is pretty much fine. Well, apart from load-related or intermittent issues, but both those are fairly rare.

Right now I am not 100% certain if EAY39190301 has such an option and if it does whether it is on or off by default. (if there is, it is always configurable through a controlling pin; it's usually labeled "AUTO").

I am quite certain that your board's cousin (or perhaps brother would be more appropriate) does have such an option and it is ON by default. In other words, when EAY41360901 is supplied with AC and nothing is connected to change the ON signal the board will automatically engage all output circuits and Vs will become immediately available.

Hope this helps!

LJ92-01436A / LJ41-04516A Y-Main sustain post-repair question and answer

Synopsis: Below is a post-repair email exchange we occasionally get after servicing and sending back a plasma TV sustain board to a customer.

I can't say this is very common, but it happens often enough to justify exemplifying it.

Both the question and the answer are valid for any other type of sustain board I know.

Equally importantly, this is a great illustration on why one shouldn't write a nasty and sarcastic note to a service that just sent back a module which didn't make the things work as expected.

Luckily this particular customer wasn't that type, but, no offense meant, enough are.
And it only takes one bad experience to spoil a whole day, sometimes a whole week.

So next time you send us LJ92-01436A / LJ41-04516A Y-Main for repair (or any other module for that matter) and it doesn't work...please do not automatically conclude it is us!
 - Bobby

---

From: the_inxpensive_xperts
To: coppelltvrepair
Subject: Re: Other: the_inxpensive_xperts sent a message about LJ41-04516A Y-MAIN SUSTAIN YSUS REPAIR SERVICE - READ THE LISTING! #160997579922
Sent Date: May-29-13 06:34:04 PDT

Dear coppelltvrepair,

Hey, got the boards, everything looked great, one problem, my screen looks like this, (in the pic), I thought maybe a loose ribbon, but I went back through them and they all were secured. Any ideas as to why it looks like that?

- the_inxpensive_xperts

---

From: coppelltvrepair
To: the_inxpensive_xperts
Subject: Re: Other: the_inxpensive_xperts sent a message about LJ41-04516A Y-MAIN SUSTAIN YSUS REPAIR SERVICE - READ THE LISTING! #160997579922
Sent Date: May-29-13 06:44:53 PDT

Dear the_inxpensive_xperts, The problem on this screen is caused by missing driving signal in the ADDRESS portion of the display matrix (as opposed to the SUSTAIN portion, which is responsible for the horizontal lines). The addressing of the display is the vertical lines in the display matrix and they are manupulated through the bottom of the display. What you have is caused by one of two things: 1) Missing power to one of the boards sitting under the display and feeding information to the display panel 2) Damaged register/multiplexor ICs embedded in the display The later is not reparable and is usually manifested in one single strip 2-3 inches wide, but it can be more such strips too like in your case; still if I have to guess I'd go with the former option as failing address registers usually cause total shortage. But as for possibility both are possible. One thing is certain: this is neither a sustain board nor buffer boards. They handle the HORIZONTAL lines of the display and you have a total VERTICAL issue. Just to help you avoid wasting time looking for a problem where there isn't one... - coppelltvrepair

---

From: the_inxpensive_xperts
To: coppelltvrepair
Subject: Re: Other: the_inxpensive_xperts sent a message about LJ41-04516A Y-MAIN SUSTAIN YSUS REPAIR SERVICE - READ THE LISTING! #160997579922
Sent Date: May-29-13 07:14:46 PDT

Dear coppelltvrepair,THANK YOU! it was a logic ribbon all buggard up. Fixed now. A little alcohol and a q tip lol. Hooking the HD back up and should be a great picture again. I just ordered the new buffers. Thanks again man.

- the_inxpensive_xperts

Repairing Proscan 40LD45Q with power supply AYL400201 - part 1

Introduction

In a chain of articles I'll summarize some knowledge and experience repairing Proscan 40LD45Q LCD TV and more specifically one of its implementations.

This first article will briefly explain the main modules in the TV.

It could also serve as a generic introduction to the LCD TV family in general.

I do not pretend to be presenting you with an in-depth and detailed know-how here , let alone specific information on how to fix exactly your particular problem.

I apologize about that in advance - this is the classic problem of someone knowing too much , all of which is important and trying to teach someone who wants a small and exact portion of the knowledge right away, but is unable to describe which one - in this case because that is only an Internet blog which goes mostly one way.

Like many other modern TVs Proscan 40LD45Q is known to come with several modifications, all under the same model name. This creates confusion when it comes to supporting, because one would easily assume that the TV has this and that board inside and order replacements only to find out that the actual boards inside are different, then usually turn back and shoot at the vendor who tricked them into believing they weren't.

Beyond any doubt it will be our fault if your TV does not match the contents of this article and here in this statement we admit to that once and for all.

Take it for what it is , make most of your personal use of it (meaning: not for profit and not for distribution unless permitted by us) and if you have questions feel free to use one of the following paid resources at our site:

• Repair kits and repair services for Proscan 40LD45Q 
• Repair services, repair kits or trade-in/exchange services for AYL400201.
• TV repair consulting service links 

In these articles I will sure miss (not omit) giving some important details and will definitely not cover all possible failures. But I will hopefully get you started enough and what I'll share will be based on personal experience and as such hopefully useful to others in the same boat.


What's inside Proscan 40LD45Q LCD TV?
Before we discus problems and solutions let us quickly go through the common suspects in Proscan 40LD45Q.

Most boards inside are relatively cheaply made and that includes both design and implementation. Clearly cost/efficiency was crucial and not durability / support costs.

The list isn't complete, of course as anything existing can go bad, but definitely those are the top usual suspects:

1. Power board AYL400201 / AYL400202

     Again, there are several modifications of the TV which have different power boards inside.
   
     There are also AYL400203 / AYL400204 boards (also called RE46AY2501 and RE46AY2502) and there may be newer ones that we don't know of.

    This article covers AYL400201 / AYL400202 and since AYL400203/ AYL400204 are clearly very similar chances are good they will also have the same functionality , even if with some minor differences, and logically most if not all of the same problems that the original ones tend to develop.

     The power board has a built-in inverter providing high voltage needed to activate the fluorescent lamps behind the LCD with the help of the back light inverter distributor.

    Like most LCD TV power boards this one has two major modes of operation: standby mode producing only +5V power needed for the standby circuit in the main board which is capable of waking up the TV set, and full activation mode where all output voltages are produced and passed to the main board and the inverter board.

   The "standby" mode in this set is kind of cheesy in that it is actually only pretending to be "standby": half the operating voltages (+5V, +12V, +24V) are actually produced at all times, but the +12V and +24V are stopped at the board's output and not supplied to the main board until the full mode is activated. Nothing principally wrong with that other than the drop in efficiency.

  In full mode the power board can also produce the high voltage needed by the inverter board. It does that when told by the main board (there is a separate command for this purpose) and it will only work after the board has been activated in full functionality.

  On AYL400201 / AYL400202 the back light (CCFL) voltage generation circuit is separate from the other three voltage rails (+5V, +12V and +24V). If you're familiar with LCD TVs you may naturally think that the back light inverter is powered from the 24V rail, but it isn't. It is completely independent.

  The 3 operational voltages (all derived from the same transformer on the board) are all equipped with over- and under- voltage protection meaning that if output voltages start derailing too much from their designed levels will cause the circuit to turn off the connection with the load, i.e. the main board. 
It is worth noting , however, that the "cutting off" is exactly that - opening a switch (done via MOSFET transistor) to the main board; the power board itself will still continue to produce the output voltages, only not pass them to the main board).

  The CCFL output (to the back light inverter board) has a similar protection, which will turn its circuit off if it detects over-voltage or under-current (and most likely also under-voltage and over-current).



  The power board is covered with protective shield, which makes testing it a bit challenging as often times the probe may not be making a contact with an element when you might think it does.

2 Back light inverter board  CMO D022899 or AUO 19.40T02.006

  The inverter board used depends on the back light assembly used and manufactures change that based on they only know what, but one clear difference between the two is that one has 10 outputs for lams whereas the other only has 8 outputs for lamps.

  The back light inverter we've seen with AYL400201 is the CMO D022899 which has 10 outputs.

  Neither of these is a typical inverter board, actually, since the high voltage has already been produced in the power board. Still there are enough high frequency coils that could possibly go bad and maybe sometimes they do.

  It would be fair to say, however, that we haven't seen enough of those boards being bad. This observation is also supported by the very low cost and great availability for them on Internet TV chop shops.

3 Main board 9RE01ZR772LNA5-A1

The main board 9RE01ZR772LNA5-A1 of  Proscan 40LD45Q is the green one with all the inputs on it.

It takes +5V standby power from the power board, which runs a small and simple circuit , which listens for a power on button pressing or infrared power on signal; upon receiving them it sends back +5V to the small IR/LED control module this activating a small LED at the front of the TV, sends back +5V ("power on") signal to the power board and finally wakes up and transfers the control to the microprocessor, which takes it from there and runs the TV.

When the microprocessor launches it does a few essential checks (e.g. "Are all power supply voltages in range?" and  "Do all of my peer devices report they're OK?") and then starts delivering your usual TV experience.

Main boards do lots of stuff we are not about to cover here. There's a lot on that subject on Internet.

4) LCD controller (T-CON) board CMO D023960

T-CON comes from "timing controller" and this comes from the role this piece of hardware works in the TV.

Basically it takes the raster (meaning pixel-by-pixel, as opposed to vector for example where objects are described by vectors like in computer video accelerator cards) image from the main board, frame by frame and for each frame it creates the signals driving the LCD panel so that it replicates the image thus allowing you to see it on the LCD output.

Because T-CON board affects the whole screen - it barely transforms the information from raster format to serial format needed to activate the individual pixels in each row and column of the display matrix - then any defect in the T-CON usually affects the whole display and not just portions of it.

Common failures in T-CON boards are burnout of the main power supply line fuse (an SMD fuse usually close to the input cable connector), shortage of a component on the board (a capacitor or input power surge protector diode, usually located right after the fuse) or failure of an IC usually due to overheating or a shortage in the panel itself.

Next part:
Proscan 40LD45Q with AYL400201 completely dead, turns on and shuts off and other problems and repairs