Tuesday, February 24, 2015

Repair dead Samsung HPS5053X/XAA, bad PSPF501A101A power supply

A customer brought in an old Samsung HPS5053X/XAA.

We've repaired and sold a lot of Y-Main boards for this TV in the past , but when we moved to our current location in the middle of 2014 we broke our own unit and haven't been able to repair and sell those boards anymore.

So naturally we assumed the problem was in the Y-Main, but it wasn't.

The TV was totally dead and that pointed towards the power supply, which is PSPF501A101A :

We tested the board in-place (in the TV) and it was lacking 5V standby.
All fuses tested out good and we had to take it out for further investigation.

All power components tested good and there were no visibly bad electrolytic capacitors.

We ended up finding the rectifier for the standby voltage output being shorted. 
This is the diode DB864 that sits on the secondary winding of the small transformer producing the standby voltage:

On the above picture the diode is already taken out of the board, sorry.

It was SB5H100, which  is a 100V / 5A rectifier.

It doesn't need 100V on the secondary side of the standby and frankly I am surprised it needs 5A, but if they used it then probably there was a good reason for it.

We didn't have a through-hole 5A/100V diode, so we used an SMD one that  we put on the other side of the board:

The board worked just fine afterwards and so did the TV.

Hope this helps someone save $100 or so for a replacement board.

Saturday, February 21, 2015

IC2 for MLT198L

It feels like we're getting somewhat of a "last hope" outlet for people with hopelessly old TVs :-)

An MLT198L power supply from ILO LCT42HA36 about my age was sent to us with request to repair it as parents or grandparents are attached to the TV.

After doing some digging on the board and digging online I found that people were stumbled trying to find replacement for the PWM driver IC for the standby circuit.

At least in few different online discussions the question has been asked and wasn't answered.

Oddly, there's a schematic for the board available (google for it, you'll find it) and there in place of the IC label there is just a question mark (?).

That tells me someone even more dedicated than us must have spent the time to not only reverse-engineer the schematics of the board, but also put it in a CAD and post it.

Either that or took an original and removed the label of the IC.

I choose the former.

Anyway, we have IC2 for MLT198L available at our online store if anyone still needs it.

Thursday, February 19, 2015

Repair LJ44-00143A / PS-426-PH power supply out of Philips 42PFP5332D/37

This board is from the fairly old Philips 42PFP5332D/37 plasma TV, but we received it from a customer with request to repair as they said they couldn't find it anywhere and nobody wanted to help them.

The board had a blown main fuse so the whole TV was totally dead (which correctly pointed the customer to the power supply), but all power components bench-tested fine.

So we replaced the fuse, took cover and plugged it in.

It took a second, but the board started crackling and sparkling.
I actually can not testify to the later as I was careful watching elsewhere (I always do when I test power boards), but I definitely heard it.

All the commotion has somehow gotten the tech working on the board by surprise since I could hear the crackling sound for long enough to start debating in my head if it is from a failing thermistor or what.

The failing thermistor was the best I could come up with.

Then AC was stopped and the board went quiet. Strangely, the main fuse was still good.

The brave tech said that the sparks have come from the sub-module between the second and third heat sink left to right. You can see his mark and arrow pointing to it at the above pictures.

However, when inspecting the sub-module I found nothing that would match the fairly loud cracking I've heard for 5 or so seconds. A small board like that should have been fairly well smoked.

Nothing was - nothing on the sub-module, noting else around.

So, after some meditation and recollection of past experiences I opted to take out the two large filter caps (which seemed fairly well and were holding well too).

I found this:

Considering this was my first try on the board I figured today must be my lucky day and called my wife probing my chances for the night. She said she's planning to have a headache again so for your luck I continued doing the board instead.

Now, the extensive burn looks pretty bad at a first glance, but after some cleaning we got this:

You can now see the track going left to right that was almost fully burned. The coat has been cracked and wiped away and you can see the copper there as well as the burned PCB layer underneath.

I bring this up because when the PCB layer burns it is important to cut or scratch it out until you get to a good material. This is because burned PCB tends to have very low resistance and is a great risk for repeat arcs that can do more damage.

The task is not unlike that of a good dentist - all bad material has to be removed until you hit solid one and only then the actual restoration can begin.

This is true for all PCB burns. I've seen it a few times in sustain boards and many times in plasma buffer boards.

So we scratch the burned PCB and take extra care around and under the edges of the damaged track.
If necessary - and it is necessary - we break the track to make sure we eliminate the bad material underneath it:

As you can see I've cut the copper track and made the hole bigger only so I can be sure there's no more burnouts.

Now, there were several possibilities for restoration.
I considered running a cable at the back side of the board. It would have been the safest and easiest approach, but the track going to the LEFT (under the heat sink) splits into three smaller ones, each of which gets a contact point I could run a wire to, but it would have given current to the other two at 1/3rd of the width of the original track.

Chances are it would have been all right, but I decided to run a jumper there, right under the capacitor.

That means it'll have to be lifted (will have to use silicone to prevent vibrations) and that I'll have to take extra care for separating the jumper from the capacitor.

Here is how it went:

 The last step was covering the two soldered ends of the jumper with coating. I did that, but forgot to take a picture and then left the shop.

Tomorrow I may cover the whole thing once more with some insulation and debate on whether to place something at the other side of the center of the capacitor to make the raising even.

Either way, the important thing was to show a problem on a board that can't be found and which is likely going to happen on others due to their aging plus bring attention to the proper way of addressing the burnout PCB issue.

While looking at the board I noticed a few smaller capacitors that did show signs of aging . Tomorrow I'll go through some if not all of them with an ESR meter, replace the ones that are off and try the board again.

I am pretty certain the board will work.

In case you haven't noticed I am good at doing boards.

And not so much my wife.

Thursday, February 12, 2015

Repairing 1AA4B10N2020A / PWB.CONTROL.N4SG button board for Sanyo DP42647 , Sanyo DP42848

I never thought I'd be blogging about such a thing, but two events not too far apart from each other made me.

First, about a month ago while ghosting around before leaving the Coppell TV Repair shop for the day I manager to somehow kick one of the Sanyo TVs we have sitting on the floor for testing repaired main boards and broke its buttons board.

Naturally, I cursed loud and set to fix it, checking first if it isn't just cheaper to buy one.

To my surprise there was none on eBay!

I mean yes, people don't keep their TVs open on the floor and kick them every now and then like I enjoy doing before dinner, but this is eBay where you can things like "Vintage Batman Anchor Hocking Milk Glass Cup, National Periodical Publications" and that's even before getting to erotic periodicals from the 40s that can only turn on (in my opinion) the camp fire and still with external help.

Anyway, I had to fix it and after some more cursing I got it to work and forgot about it.

Then a few days ago one of our customers asked if we can find that same board for him because he broke his.

And today his came and I fixed it again. It was broken in a very similar fashion.

Repairing is not a rocket science, but requires fine sold tips, solid hand and some patience.

On the above picture you can see how I've added one metal rod (what's the better word for that) for support on the top of the board and here's the bottom:

If you happen to break your board and can't fix it yourself feel free to drop us a line.

It'll be about $25-$30 in total (as it takes a good 20 - 30 minutes)  and the best way to start is through http://www.coppelltvrepair.com/newservice .

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...the marketing pitch :-)

1) Here's where you can buy replacement IPMs for 6871QZH060B .

2) Here's where you can buy replacement ZSUS board 6871QZH060B.

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.