Plasma 42V7 problem - please help!!!

[scokljat]

Re: Plasma 42V7 problem - please help!!!

My work place has the 100 MHz version of that scope. I *think* it only has edge and video triggers. But yours may be slightly different. Press TRIGGER MENU and see what options you get. You can still get a decent trigger without, just requires playing around with the HOLDOFF control, which this scope definitely has (had to use it on one circuit with a data line with varying frequency.)

Yes, you are right - on my scope edge and video triggers only.
Are we 100% sure Y-SUS IPM is bad? I done Y/Z-SUS IPM diode check (service manual) and I think it checks OK (see pics). What about other FET's and caps on Y-SUS board?

I see cheapest Y-SUS on ebay (UK) is around 70$ with shipping, and it's USED, so it can happen it fails again soon. Very expensive.

Thank you very much for your help!!

Cheers,

S

[scokljat]

Re: Plasma 42V7 problem - please help!!!

Does your scope have a pulse-ramp rate trigger? Try triggering on the slow VSET ramp; it ramps up over several microseconds.

It sounds like your Y-sustain is faulty. This issue can be caused by a walking-wounded IPM.

Tom, as new/used Y-SUS is too expensive for me I found lot of IPM modules on Ebay. Price is from 16 - 25$ including shipping. IPM used in my 42V7 set is YPPD-J014A. Some sell USED IPM togedher with heatsink, and I found lot of "manufacturer refurbished" IPM's from china. What the heck is "manufacturer refurbished"??!

Also, there is Sanyo STK795-811A which they claim is the same as original YPPD-J014A. Sanyo STK795-811A can be found "NEW" for 15$.

What do you think should I go for "manufacturer refurbished" YPPD-J014A or "new" STK795-811A??

Also, what other things to check and/or replace on Y-SUS board before I change IPM? Is there and way to test IPM module (other than IPM diode check in service manual)? And finally, I see people have problems with power supply that go to IPM (usually 15-18V). How can I check this voltage? And what about caps?

Thanks!

Cheers,

Suad

[scokljat]

Re: Plasma 42V7 problem - please help!!!

Does your scope have a pulse-ramp rate trigger? Try triggering on the slow VSET ramp; it ramps up over several microseconds.

It sounds like your Y-sustain is faulty. This issue can be caused by a walking-wounded IPM.

I just measured +15V IPM input voltage and it's OK both for Y-SUS and Z-SUS IPM (+15.29V).

Voltage converter for IPM +15V is on Y-SUS board and it goes through CTRL board to Z-SUS board. (see pics.)

My first step will be to change Y-SUS IPM, but I'm in doubt to change all Y-SUS caps as well. There are 29 caps on Y-SUS and 7 caps on Z-SUS. 20$ for IPM and 30$ for caps - not cheap...

[Cailloux]

Re: Plasma 42V7 problem - please help!!!

Some suggestion.
In the service manual, it says LED1 on the power supply, is it blinks when the picture is black?
Did you check the boards with a magnifying glass to detect cold solder?
Do you have a ESR tester (Equivalent Series Resistor) to check the capacitors?
Connect the oscilloscope on the power supply Vs, Va, 5V, etc. .. are they really stable when picture come in and out?

[scokljat]

Re: Plasma 42V7 problem - please help!!!

Some suggestion.
In the service manual, it says LED1 on the power supply, is it blinks when the picture is black?

There are two types of PSU for 42V7 series. Mine is one without status LED's and without AUTO/NORMAL switch. It's a LG YPSU-J006A and it's not described in service manual.

Did you check the boards with a magnifying glass to detect cold solder?

Yes I checked Z-SUS and Y-SUS for cold solders and I pounded through all boards, caps and heatsinks with screwdriver handle - no difference.

Do you have a ESR tester (Equivalent Series Resistor) to check the capacitors?

No I don't have ESR meter. I only have cheap digital multi-meter and 60Mhz scope. However, I took 7 10uF/350V caps from Y-SUS and checked them with my meter, they are all around 8.5uF except one that was 7.5uF. I changed place of weakest one - no difference. My multi-meter can measure caps of max. 20uF.

Connect the oscilloscope on the power supply Vs, Va, 5V, etc. .. are they really stable when picture come in and out?

I just tried that. Vcc +5V checks OK, Vs +187V checks OK, but Va +65V has some ripple. Ripple vary from 1V to 3V doesn't matter if there is picture displayed at that point. Sometimes it ripples more, sometimes less, but no more than 2-3V. Is it normal to have that ripple on Va??

I noticed one more thing. Voltage readings with my scope are different than when I measure with multi-meter. ?!? Scope reads +192V, multimeter reads +187V, or +5.2V/+5.04V, or +65V/+68V. Which one to belive? Cheap multi-meter or Tektronix scope?!?

And one more thing, what is normal temperature for IPM heatsink after 30 minutes of operation??? On my Z-SUS board it gets hot so I can't hold my fingers on it more than few seconds. Is it normal?? However, IPM on Y-SUS is almost cold so it indicates that most of the time it's not working. Heatsink for Y FET's (10 FET's under heatsink) is also almost cold... None of that FET's is shorted.


I recorded a movie and pics of scope measurement, take a look:

http://www.youtube.com/watch?v=tGKZ0Qn3d4U


Thanks,

Cheers!

Suad

[tom66]

Re: Plasma 42V7 problem - please help!!!

It's only a 480p panel so don't spend too much. I would think refurbished could just as well mean fake!

[Cailloux]

Re: Plasma 42V7 problem - please help!!!

I just tried that. Vcc +5V checks OK, Vs +187V checks OK, but Va +65V has some ripple. Ripple vary from 1V to 3V doesn't matter if there is picture displayed at that point. Sometimes it ripples more, sometimes less, but no more than 2-3V. Is it normal to have that ripple on Va??

I noticed one more thing. Voltage readings with my scope are different than when I measure with multi-meter. ?!? Scope reads +192V, multimeter reads +187V, or +5.2V/+5.04V, or +65V/+68V. Which one to belive? Cheap multi-meter or Tektronix scope?!?

And one more thing, what is normal temperature for IPM heatsink after 30 minutes of operation??? On my Z-SUS board it gets hot so I can't hold my fingers on it more than few seconds. Is it normal?? However, IPM on Y-SUS is almost cold so it indicates that most of the time it's not working. Heatsink for Y FET's (10 FET's under heatsink) is also almost cold... None of that FET's is shorted.

Suad

Voltage readings are good, ripple also.

The scope or multimeter is poorly calibrated. Use a know good reference to check.

The majority of plasma that I repaired, the Y main is very hot more than the Z board. Very hot for the fingers. In your case, the picture switch on / off, your Y is less request, this is probably the reason it is colder than the Z. I install two fans on the rear panel, can help prolong the life of the TV.

[scokljat]

Re: Plasma 42V7 problem - please help!!!

I measured all signal lines that go from CTRL board to Y-SUS just to see if there is some difference in signals when picture is black and when TV shows some picture. I did measure with scope, it's a 60Mhz and not 200Mhz but it's enough to see if maybe incoming signals are reason because Y-SUS IPM and FET's are switching ON/OFF...
Unfortunately when I recorded the video (with two cameras) it didn't happen that TV showed picture.

Video:
http://www.youtube.com/watch?v=uFqVFMkP2oI

Btw, I'm getting better and better in recording movies, right? ;-)

Do you think first signal sucks little bit??

For now it didn't happen to have scope probe ready and TV to show picture, so I'm not sure if first signal jumps when picture appears... It's maybe just clock...


Cheers,

Mr. Spielberg ;-)

[scokljat]

Re: Plasma 42V7 problem - please help!!!

It's only a 480p panel so don't spend too much. I would think refurbished could just as well mean fake!

Well Mr. tom66, I know it's only 480p panel, BUT now for me it's THE 480p panel which I spent days to troubleshoot and learn about it and trying to fix it. So, here's what I'm gonna do - I gonna fix this bastard (with your help, ofc) and put fans inside to cool it down, than find and buy original stand and remote for it, and then i gonna install it to my parents house! ;-)

Well, honestly, I think this forum is ultra great place for people to learn something and to actually successfully repair their stuff, thanks to people like you and your unconditional help. Also, I believe that my thread will help other people to fix their TV's so I'm trying to be detailed, post lot of pictures, movies, measurements, annotations... At the end of day, that IS the basic principal of this forum.

Now, help me repair my plasma! ;-) ..just kidding

Thanks and cheers!

S

[scokljat]

Re: Plasma 42V7 problem - please help!!!

Voltage readings are good, ripple also.

The scope or multimeter is poorly calibrated. Use a know good reference to check.

The majority of plasma that I repaired, the Y main is very hot more than the Z board. Very hot for the fingers. In your case, the picture switch on / off, your Y is less request, this is probably the reason it is colder than the Z. I install two fans on the rear panel, can help prolong the life of the TV.

I borrowed Fluke 175 multimeter and confirmed that my multimeter also shows correct voltages. I did all plasma voltage adjustments again...

[scokljat]

Re: Plasma 42V7 problem - please help!!!

Today I desoldered out IPM module. It was LOT of work, one and half hour at least. I used Weller 50W soldering iron, solder wire, paste, solder wick and pump.
I'm quite pleased with result, there is no damage to PCB, traces or vias.

Now, IPM looks tidy from inside, there is no visible damage, no exploded or shorted transistors or diodes what is not unexpected as IPM was producing picture from time to time, but very rarely. Maybe malfunction is in control part of IPM and not in power part which is i believe uncommon. I checked it with spy glass it looks ok. Now I'm little bit worried that maybe real problem is somewhere on Y-SUS board and not in IPM itself.

Now about IPM type, I expected LG's YPPD-J014A or YPPD-J014C inside as it's common for 42V7 plasmas but this one is different. It has two large control IC's and no LG logo or part number. All written inside is "Rev. 3 20UP30 050712". On heatsink there is label "4921QP1037A" which is I believe part number for IPM module and heatsink together. I searched the web and ebay, all three are available as used or "manufacturer refurbished" (whatever that means) or "new" Sanyo STK795-811A which would-be compatible with YPPD-J014A and YPPD-J014C.

My questions:

1. Is LG's 4921QP1037A IPM same and 100% compatibile with LG's YPPD-J014A or YPPD-J014C or Sanyo STK795-811A?
2. What is difference between LG's YPPD-J014A or YPPD-J014C?
3. Which of all four IPM's is the best??

I saw some posts where people had some red sparkles on screen after they installed Sanyo IPM...

Cheers!

S

[tom66]

Re: Plasma 42V7 problem - please help!!!

You might have to undo the heatsink to reveal the IPM's true identity.

[scokljat]

Re: Plasma 42V7 problem - please help!!!

You might have to undo the heatsink to reveal the IPM's true identity.

Of course I removed the heatsink, and guess what? Nothing is written on top. Nothing on top, nothing on sides, no stickers or engravings... A mistery?

There is model number on the sticker on the heatsink, it says "4921QP1037A" and inside IPM on the PCB says "20UP30". When I searched the web for "20UP30" I acctually got some chinese sites (as usual) to request a quote. Pictures on that sites are of actual IPM. There are few of them listed on ebay...

Cheers!

S

[scokljat]

Re: Plasma 42V7 problem - please help!!!

Today I bought Sanyo STK795-811A IPM from Ebay. After all things taken into consideration, I think it's the best option. Sanyo is "new" and all other original LG IPM's are used or "refurbished". Now I have to wait, shipping takes 2-3 weeks...

I asked Coppel TV repair about Sanyo (STK795-811A) vs. original LG IPM's for 42V7 plasmas (4921QP1037A, YPPD-J014A, YPPD-J014C). I got all answers promptly. Finally I resolved all my doubts about Sanyo STK...


My questions:

----

1. If I install STK795-811A replacement IC in my Y-SUS do I have to adjust Va, Vs, Vsc and -Vy differently or same as on my original panel sticker?

2. If I install STK795-811A replacement IC in my Y-SUS do I have to replace IPM on my working Z-SUS also with STK795-811A or I just leave the original working one?

3. Is the STK795-811A 100% compatibile with original and do I have have to make any more modifications or adjustments to my Y-SUS board and will picture be 100% OK if the rest of my Y-SUS is OK? I heard some rumors that people get some sparkles and deformations on picture with STK795-811A.


Coppel TV answers:

1) You shouldn't have, but you may have. This may or may not be related to the IC replacement - the same adjustment could be needed (or not) if you replace J014 with the same J014; in other words, the answer to the question does not depend on the IC being replaced

2) The functionality of the YSUS has nothing to do with the functionality of the ZSUS except the fact that they work at the same time and over the same load; they are "synchronized" by the external signals that drive them. I always make the parallel with car tires...it is very very similar.
But the answer to your question is no, you don't need to change the module on the other sustain board.

3) As the listing states the 811A is 100% compatible with J014; LG themselves uses it on their own boards, I suppose a matter of supply availabilities.

----

Here are pictures of all four IPM's...

[tom66]

Re: Plasma 42V7 problem - please help!!!

My answer for 1) would be:

- No, the voltages are purely for the plasma panel discharge and the IPM characteristics shouldn't affect it.

[scokljat]

Re: Plasma 42V7 problem - please help!!!

Did you see my new avatar ;-)

[scokljat]

Re: Plasma 42V7 problem - please help!!!

Just a quick update:

- waiting for new IPM module to arrive
- waiting for ESR micro V4.0 to arrive :-)
- trying to build universal IPM desoldering tool for easy IPM removal
- getting nervous and suspicious that my IPM module is maybe OK and the malfunction is somewhere else...

Cheers!

S

[scokljat]

Re: Plasma 42V7 problem - please help!!!

Got Sanyo STK IPM module from Ebay today! Just took it, unpack it and I had to go out of town for a few days, so I'll install it on Sunday. Well, first what I noticed it looks used and refurbished and NOT "new" like it was listed on ebay. There is solder on terminals, it looks like it's desoldered, cleaned and new solder applied. Does not look new and I have a feeling I'll leave some negative feedback if seller can't find very good excuse. Will post pictures...

Stay tuned...

Cheers!

Suad

[scokljat]

Re: Plasma 42V7 problem - please help!!!

Here are pictures of Sanyo STK795-811A IPM module I bought from ebay as replacement for original LG 4921QP1037A. It was listed as"new-other". I have sent inquiry to the seller what it means "new-other" and was the item used or installed in TV before and than desoldered and refurbished. I got the answer that item was not used before and it's a brand new item NOS, and it maybe can have some scuffs.

Well, "some scuffs" is ok but this item has obviously been used before, there are scuffs and marks of screws that attach IPM to heatsink, all legs are washed over with new solder, and some legs are cracked and deviated little bit (see pictures).

What do you think? Is it new/other or used/refurbished??

I did a quick test for shorts and it looks OK. I believe it's maybe functional but if it's not, second time if I desolder IPM from that YSUS board it would result in damaged traces, vias and destroyed PCB. STK has one leg more than original IPM, but there is a hole for it on PCB, it's a CHGND ground.

Maybe I should put M3 screws with nuts from underside so if I have to remove IPM again, I just unscrew Heatsink and then cut all IPM legs, remove IPM and desolder all legs one at a time.

Cheers!

Suad

[scokljat]

Re: Plasma 42V7 problem - please help!!!

SUCCESS!!!!!!

After lament about lame IPM module I decided and finally installed it. It works!! TV has picture again. Picture is almost OK. Almost...

Well, picture is sharp, bright, colors are vivid BUT there are some sparkles on pixel basis and when something full white is displayed (like subtitles) when it disappears there is light shaddow like memory effect which slowly disappear in 1-2 seconds. I believe (and hope) it's because of misadjustment. Vs, Va, Vsc and -Vy are adjusted like on label. There is no adjustment of Vzb on my ZSUS so I beleive it adjusts automatically. VZB is not even written on label.

Two things are definitely misadjusted - VsetUP and VsetDN. When I slowly adjust VsetUP or VsetDN sparkles and ghosting changes but I'm unable to adjust it correctly. VsetUP and VsetDN are for adjusting output waveform and should be adjusted using oscilloscope (see pic). I'll try tomorrow, I hope it will work. I have to borrow second probe...

What could be other causes of this little sparkles and slowness of bright areas?? Do you think I should try and experiment with little lower/higher Va, Vs, Vsc, -Vy voltages? I also noticed label says "DC 5.2V"?! Does it mean I have to adjust 5V as 5.2V? Now it's adjusted exactly 5V measured directly on PSU output connector.

Acctually I'm quite happy now, we are making some serious progress here

Thanks!!!

Cheers!

Suad