Sunday, January 25, 2015

Panasonic TC-P42S30 bad TNPA5349 causing clicking on and off

If you are following this blog for a while you may have noticed I rarely ever post about Panasonic plasmas.

Customers often ask us if we can fix one or other TNPA board and we usually answer we do not work on Panasonic boards.

When talking to laymen and not service tech the next question is almost always "are they that bad?".

No, they are not. Or not much worse or much better than the others.

We just do not have the resources to repair the three major plasma TV manufacturers in the world.

Before that changes plasmas may become obsolete and I'd like to use that chance to give a clue on repairing a Panasonic TV.

A Panasonic TC-P42S30 was brought the other day in shop for repair.

Here's the label from the back and here's the TV look after you take the back cover off:



Failure symptoms: The symptom was as stated in the title: the TV would click on, produce no image and click off within a few seconds. It may have been giving an error code through a number of blinks on the power LED, but I did not pay attention to that.

Troubleshooting: Like most other plasma TVs Panasonics are know for failures in power supply boards and the sustain boards (of course some also fail in the main or elsewhere, but those are less).

The power board was clicking, which means it was getting standby power all right and the failure would have been on either the main power circuit (+5V main, +Vg (if present), Va, Vs etc.) or in a sustain board.

After a quick check on the fuses of the power as it was mounted on the TV and finding nothing we moved for a quick check on the power components of the Y sustain board (SC board in Panasonic terminology).

As you can see on the picture this is a combined sustain and output buffer board as is normal for some time now. The board in reference is TNPA5349:



We ran a quick check on the not-so-many SMD mounted power transistors and diodes and were not surprised to find a diode and a transistor that read short:


Those were the Q441 transistor DG302 and the D481 diode RF1501.

When we removed the transistor from the board the shortage over the diode disappeared and it read normal.

The DG302 transistor was the only failure on the board in this case and replacing it restored functionality of the set.

DG302 is popular choice in many Panasonic sets and is used both in its SMD and heat-sink mountable packaging.

Both DG302 forms can be purchased at our site (and likely other places).

At below $10 and relatively easy processing (compared to many other repairs) this is definitely worth doing.

A few notes I would like to make:

1) If you are into electronics and doing things right I'd recommend you get TWO transistors and enhance the stock Panasonic build with TWO transistors working in parallel. There's plenty of space to solder another one there and you'd need to run a 5.6 ohm resistor from the gate to the point on the board just after the 5.6 ohm resistor of the original Q441 is.
You'd also need to run a wire from the third leg to the third leg of Q441.
Cutting the load in two this way you can rest assured this transistor is not going to fail you again.

2) There will be cases when this transistor won't be the only thing that has failed on the board.

3) Inserting the display FPCs into the SC output connectors has been a PITA for this set.
Do not affix the SC board in place with the screws- put one or two in, but let the board loose. That helps the insertion and still be extra careful to make sure you've plugged both ears evenly in the connector.


Good luck!

Tuesday, January 6, 2015

LG 60PC1D-UE with dark image - 6871QZH060B ZSUS repair

I don't usually write about TVs we don't offer a repair for here, but I am making an exception here.

First, we may actually start offering a repair service for the 6871QYH057B YSUS and 6871QZH060B ZSUS boards eventually (search at www.coppelltvrepair.com to find out) and second, the two boards are awfully close in design to the 50'' versions utilizing the same IPM modules, to which we are probably the single biggest service center in US, possibly after LG themselves.

Anyway, yesterday we got hauled in an LG 60PC1D 60'' plasma TV for repair. Fairly old, and even more heavy, but darn it, it's well done inside:




The complaint was a dark, blotchy image and unfortunately at the time I did not take a picture of the display.

The tech who brought it (we often get TVs by local TV repairmen, probably more often than we get TVs from end users locally) said the fuse on the ZSUS board blows as soon as the TV gets started.

Actually he also said he got a replacement board from Union Electronics, but it came with a blown fuse, so they exchanged it and the second one worked for 5 minutes and also blew the fuse.

That got me a little nervous because it meant the problem could have been elsewhere , e.g. in the plasma display controller, which could have been messing the signals and overheating or just crashing the IPMs on the ZSUS board. I've seen that in other TVs, although rarely.

Anyway, at the very least it was clear where to start, so I took the ZSUS board 6871QZH060B out and checked the IPMs. There were no shorts and the E versions were used from what I could tell (YPPD-J015E and YPPD-J016E since both were thin and only had 2 screws for the heat sinks meaning they weren't C or B versions).

In the 50'' models that we've done easily over a thousand of, when the E version is used the two most common failures are 1) failure in the J016E resulting in a particular shortage; and (remote second) failure in J015E almost always resulting in one of several possible shortages (e.g. Vs to GND or SUS_OUT to GND or Vs to SUS_OUT).

Well on this 6871QZH060B there were no  shorts whatsoever.

But when I took out the SUS IPM here's what I found:


(for some reason Blogger insist on showing the picture in portrait mode; it shouldn't but I'll leave it as it is and you can mention Google favorably in an absent manner - maybe they'll get it eventually)

As you can see the SUS IPM has left a nice good proof of a failure on the board.

Since it could have been killed by a failed ER module, though, I did replace both. We always do.
Well almost always. A certain failure in the ER module alone can be treated by replacing the ER alone.
 
However a failure in the SUS module is best addressed by replacing both - that's what we've learned early in our experience with those and it has served us well.

After replacing both IPMs and the fuse (6.3A) we got this:



It worked that way for about 2 hours and then we delivered it back to the happy repairman.

We charged $120 for that and I am sure it ended up costing well over $200 to the customer.

Frankly I think it's fair if the guy had to order two boards, haul the TV to his shop and then to us and then back to his shop (where he'd be testing it longer) and eventually back to the customer.
Come to think about it..perhaps over $300.

Oh well...you know the old saying...the one with the idea gets a dollar, the one who implements it gets $10 and the one who sells it makes $100...so much for the great ideas :-)

Oh, almost forgot:
Here's where you can buy replacement IPMs for 6871QZH060B!
By the way they are the same for 6871QYH057B.

Tuesday, December 2, 2014

LJ92-01601A / LJ41-05905A / BN96-09738A Samsung Y-Main now for sale and repair

Samsung Y-Main LJ92-01601A (PCB LJ41-05905A and Samsung inventory number BN96-09738A) is used in a number of 50'' plasma TVs utilizing Samsung display panel S50HW-YB04:

  • Insignia NS-P501Q-10A
  • Samsung PN50B430P2DXZA
  • Samsung PN50B450B1DXZA
  • Sanyo DP50749 P50749-01
In the past we used to import and just sell those boards, but now that we have one of the above models we are able to offer substantially lower price by offering a buyback option for the old dud, which we can then restore and resell.

I just finished checking competition and am glad to report at at least for the time being it seems our offer seems better than the ones I've found.

We'll be adding a repair service for the board soon at www.coppelltvrepair.com, at the time being you can simply use the purchase and trade-in option for  Samsung LJ92-01601A / LJ41-05905A / BN96-09738A.

Wednesday, November 5, 2014

EAY60968701 power supply testing - how to and repair links

Question
Dear coppelltvrepair, 
thank you for your repair kit for my LG 50PJ350 (using EAY60968701 ).

I replaced all the items on the circuit board but it still doesn't work. The plasma TV still goes into sleep mode. I was wondering if you have any other ideas that I can try to get this thing working?
 

Thanks!
Sincerely,
B. Lesemann


 
Answer
What I would recommend is testing the LG EAY60968701 power supply board  to see if it works on its own and thus isolate it from the list of possible suspects.



A full proper test would require full proper load on the board, but it rarely needs full proper load to show a problem.

So, with the condition that this is still not exactly 100% reliable, there's a very simple and quick way to test if the power board is OK with nearly 100% reliability.

It is actually highly recommended you do this test before placing an order for a repair kit; either that, or just test the components listed in the kit's description to see if any of them are shorted (for semiconductors) or open (in case of resistors and fuses).

Anyhow, here's the test:

Disconnect all connectors from the board except the main AC power one.

Now connect EAY60968701 to AC and wait.

You should promptly hear it click once.

You should also be able to measure about 207V between the pins labeled VS and GND on the connector at the top left.

If you do not have a meter or are afraid to use it you can usually simply play by ear and disconnect the board after a few seconds.

You should promptly hear another click when you disconnect the board from AC, which is the normal response to a board that loses power.

If you do not hear a click the first time you connect the board or if you hear one click followed , in a second or two, by another click (without having disconnected the board) then your EAY60968701 probably has an issue and needs to be serviced.

Remember, no other cables need to be connected to the board for the test to work out!

Here is a link to our EAY60968701 DIY repair kit for the most common issues we've seen.

And here is a link to our EAY60968701 repair service .

Monday, October 20, 2014

Sony KDL-40Z4100 no image, shuts down in a few seconds problem

This article is a quick visual guide done for the benefit of one of our customers who had sent a T-CON board T400HW01 V3 / 40T02-C05 / 55.40T02.C06 from  Sony KDL-40Z4100 for repair.

Normally when that T-CON board T400HW01 V3 / 40T02-C05 / 55.40T02.C06 goes bad the result is color distortion, "solarized" images or , in some cases, washed out picture, but in this case customer reported that the TV would start normally, play sound, but nothing would show on the screen and then it would shut down on its own.

We received the T-CON board , stuck it in our TV and got the exact same result - the TV would come up for a few seconds, no image at all, then it would shut off.

Turned out the board was pulling too much out of the 12V power supply rail due to a problem.

When we located and resolved the reason for that and put the board back in the TV it  still did the same thing.

It turned out it was not supplying 12V to the T-CON board anymore, so we pulled out the main board from where the 12V come and started tracing.

Eventually, it turned out that there is a fuse on the 12V rail to the T-CON T400HW01 V3 / 40T02-C05 / 55.40T02.C06 on the main board and that it was blown open.

It's a 5A / 24V pico fuse that we did not have handy, so we stuck a different one:

This picture is of the back of a Sony KDL-40Z4100; you can see where our fuse shows above the top middle of the main board.

This is the back of the main board from a Sony KDL-40Z4100. You can see the label of the 12V fuse F1422 and our patch over it.


After installing a replacement fuse as shown above the TV stayed on and we got a good image with our own testing T-CON board .

Alas, customer's board was still showing image with too much brightness / wash out, which was not caused by the usual problem in the alpha control IC; we are still trying to figure that out and will eventually succeed.

But you should know that if your Sony KDL-40Z4100 tends to shut off within a few seconds after it is turned on and shows nothing on the screen even though the backlight comes up then you should check that fuse on the main board.

Good luck!

Sunday, October 19, 2014

Do we want to buy your old TV main or power or other boards? Find out!

The quick answer: yes, as long as they are valuable to us (rules out all tube and projection TVs) and we get them dirt cheap, preferably free.
For the long answer read below.

 
With new TV prices breaking new lows every quarter and economy in a happy bubble again (the US deficit at an 8 year low, wooo, but still a deficit!) more and more TV repair shops around the country are closing doors.

Twice this week we received calls from people asking us if we want to buy old boards from them.

The first was definitely a TV repair shop that closed doors while the one today did not say the source, only said the following:



"I HAVE SOME POWER SUPPLY BOARDS THAT I'D LIKE TO SELL. DO YOU BUY MAIN OR POWER SUPPLY BOARDS? THANK YOU. "

Well I do not know how good of a businessman I am. 
I guess I am ready to assume not the best one since I do not put profit on top and do not look at every opportunity to maximize profit.

But I've gone through enough similar questions and, without any means of offense, here's my two cents:

Solicitations like this one to buy their overstock/liquidation/about-to-be-trashed boards rarely ever end up with an actual deal.
Unless the offering party is a professional liquidator, in which case the approach looks differently, it quickly gets to a discussion about what is what what and that can drag for way too long to be worth the few or more boards one would acquire.

Then there's the uncertainty in the buyer about whether those boards really what the seller says they are; the buyer usually needs to assume worst case scenario, especially in an unsolicited offer like that, and in my limited opinion, they better do that.

Of course a honest and well technically educated person has all the right to be on the opposite opinion if they know the source and quality of their boards.

But since people are not equipped with a character and quality judging devices - at least I know I am not and none of the people around me is - we can't tell good from bad and educated from truly believing in what they say. Let alone the con artists.

So, bottom line, if you are an individual or even a TV service shop closing doors...my advice is this:

1) Make a good inventory list of what you have: part numbers and quantity at the very least, working condition if you can.
2) If you want to make the most out of your list start selling them by yourself on eBay, Amazon or wherever else you may see fit; that is the ONLY way to get anywhere close to what they'd be worth to an end customer.
3) If you want to sell to another business , then my advice is to decide how you want to sell them, i. e. as a whole lot or individual lots, e.g. main boards and power boards or Toshiba parts versus Samsung parts.
There are pros and cons to each approach and as usual your best revenue would be somewhere in between one whole lot for one limp sum (little effort, quick sale, low profit) and too many individual lots (more profit, but also more time and more effort).
The decision for that better be yours, though.

4) Make a list of the potentially interested parties; it can be as little as one, but it best be above 4-5; the more the better, only your time and will to add more should limit the number.

5) Make a listing for the lot(s) along with the inventory list on eBay or other auction site and THEN send a message to all interested parties.
Set the starting price LOW to avoid pushing buyers off; if there's a real interest and real competition they'd bid over each other and you'd get fair market price.

Note this does not put any of your buyers at an advantage or disadvantage to others; and you will end up getting a fair market value at the end.

That is, this approach saves the whole process of individual negotiation and waste of time between you and a single potential vendor.

God knows I am not the biggest fan of what eBay has grown to be; but the simple fact is that public bidding is an efficient and valuable tool when it comes to liquidation.

Sunday, October 12, 2014

A batch of STK795-821 with a bizarre defect received from China

In a number of articles before (e.g. this or this) I've written about the specifics of ordering from China.

In a nutshell it is unpredictable unless you have your people there, holding others at the Chinese equivalent of a gunpoint (maybe a gunpoint?).

One way to decrease those risks is to work with the same vendor and build mutual trust, educate them on how to avoid mistakes etc.

However even then you are not guaranteed.

We are working with the same vendor for many years now and have been together through a lot already.

Which did not prevent us from receiving a batch of STK795-821 ICs that had a problem we have never seen before: a shortage between the Vs input power (200V) and the IPM control logic driving power 15V (often labeled Vg).

Here is what I mean:


This is a picture of the bottom of a YSUS board 6871QYH053B which uses STK795-820 or STK795-821 or YPPD-J018C or YPPD-J018E etc.

I am enclosing that picture here so that you can easily see the groups of pins on the IPM.

We've sold over a 1000 ICs and repair kits and we've fixed probably just as much internally and I can easily say that 99% of all failures manifest themselves as one of the following:
  • Short between Vs and GND pins
  • Short between Vs and SUS_OUT
  • Short between GND and SUS_OUT (I am actually not sure about this one, but it's worth checking)
  • Diode effect (one-direction resistance) between VER1/VER2 (they're shorted out on the PCB) and ER_DOWN_OUT; normally there should be infinite resistance in both directions, but an internally shorted FET would leave a diode in the circuit between the two.
    The effect would be flashing on the screen.
A failed IC may also develop some other shorts, but rarely ever does or, more frankly, we rarely ever needed to search for clues other than the above.

Until last week when we received, in a box from a large batch of ICs, the following:

We've labeled the pins for you. There were 28 ICs with Vg shorted to Vs!

Unaware of that, we just processed normally a repair service for a board and proceeded to testing the result.

Bang, bang,
went PCBs,
and I assure you
bang, bang,
burned the TV...
Wait a minute, what you sold me there?
Wait a minute, that's a freakin' nightmare...
Bang, bang..

OK, enough TV pop folklore :-)

First, you should remember that resistance between Vg and Vs should always be infinite as shown below, only in both directions:


Second, you can bet that once you solder an IC that has a shorted Vg to Vs and test that in a live set, you will have A WHOLE LOT MORE damage than you originally started with.

For a starter, the ZSUS board's IC will also fail since it uses the same +15V that are produced on the YSUS board and dispatched, through the plasma logic board, to the ZSUS; but everything , or nearly everything, that is on the YSUS and feeds from the +15V will likely also be damaged.

This case is a great illustration of a few important takeaways:

1) You better know what you're soldering on a board; it won't hurt you if you test everything that you know tends to fail.

2) You are definitely better off buying ICs from someone who uses them versus someone who just imports them and sells them; you are not guaranteed unless said someone tells you they've tested the IPMs and they are honest, but you are , by all means, better protected if someone is working with the same material that you're going to be using.
We can't say with 100% certainty haven't sold a single IC of those to a customer, but chances are we didn't because we usually start using internally products from new shipments while continuing to sell the products from previous shipments - exactly for the sake of being first line of protection for customers.
Of course that is still not a 100% certain because , like in this case, only one and a half box out of twenty happened to be bad.

3) You can make a mistake even when working with a trusted vendor; that is because they themselves work with local vendors sometimes; of course that also means you would be better off being a first tier, but in many cases that is simply impossible.
Yet working with a trust vendor helps a lot resolve the problem and they would often times walk an extra mile to cushion any and all losses.

4) Maybe a bit strange for some, but for me this is a great illustration of why we should NOT warrant ICs once they are on a board. You see, a number of things can be bad on a board or in an IPM; to date I see some of my own technicians occasionally short two pins when soldering. Not those particular two, because they are quite apart, but certain other two are just sufficient.

The result would still be a failed board, sometimes filed buffer etc.

Any mistake - be it internal or induced - can cause a lot of damage.

A responsibility line must be drawn somewhere and I do not see a better place of running heavy current through the IPM.

We can't easily catch this particular case and the next best is just soldering the IPM on a board.

I'll finish this article with another two pictures for a different board we received from our vendor and the problem with it. The board was returned by a customer who claimed there were was a horizontal bar of about 1/8th of an inch that was dark no matter how may times he adjusted the plasma display ribbons to the connectors:


This is a Samsung Y-Main board LJ92-01601A used in Samsung PN50B450 and others.
It has an embedded YSUS buffer.

And this is what we found out upon careful inspection:



There was simply a cut through the PCB that has disconnected 4 tracks. This picture is made after we've removed the silicone, cleared the tracks and prepared them for connection.

The IC did NOT seem to have been reworked, but I can not see another explanation of how this could have happened.

Good luck in your own repairs!