HP 50" Plasma TV, Model: CPTOH-0603... plz, need help troubleshooting

[ngc1068]

Re: HP 50" Plasma TV, Model: CPTOH-0603... plz, need help troubleshooting

I would consider the chance that your multimeter battery is low, causing incorrect readings.

It seems strange tho that Vs and Va were at-spec within a volt or so, and I adjusted them to under a quarter-volt error.

I did check the DMM on my car battery, on a few AA batteries, and wall AC voltage. All seemed reasonable.

Do those values for Vy and Vsc seem right? Am I reading the panel sticker correctly? Vy=-200 and Vsc=120 ?

I guess maybe at higher voltage my DMM could be breaking down. Its a Fluke 867B Graphical ScopeMeter.

[tom66]

Re: HP 50" Plasma TV, Model: CPTOH-0603... plz, need help troubleshooting

I would consider the chance that your multimeter battery is low, causing incorrect readings.

[ngc1068]

Re: HP 50" Plasma TV, Model: CPTOH-0603... plz, need help troubleshooting

Wierd.

I adjusted Vs and Va per the specs on the panel, they were off maybe 0.5V and 1.5v respectively.

Then the label on my panel shows Vy of -200 and Vsc of 120, right?

The values on my Ysus board were quite a bit lower than this (stupid me didn't even record the as-found values...)

So I adjusted them per instructions to within 0.25V of -200 and 120, with the TV in "white".

Well, got around to the front and found the panel all dark and deep red in color...wtf?

I went back in a panic, and double-checked the voltages, they were -200 and 120 still... ok... something wrong here.

I went and adjusted them to -160 and 80, just as a guess. Panel looks perfect now, no mal discharge at all. No sparkles, TV looks awesome.

I decided to leave well enough alone, and put it back together, lol.

[capkid]

Re: HP 50" Plasma TV, Model: CPTOH-0603... plz, need help troubleshooting

It can get better with the right combination of tweaks, but it most likely won't completely go away. Trust me, I've tried on numerous LG TVs, as has Tom.

[ngc1068]

Re: HP 50" Plasma TV, Model: CPTOH-0603... plz, need help troubleshooting

Does mal discharge ever get better from making adjustments alone? Is it possible it is simply an adjustment issue?

[capkid]

Re: HP 50" Plasma TV, Model: CPTOH-0603... plz, need help troubleshooting

I've attached the panel alignment guide.

[tom66]

Re: HP 50" Plasma TV, Model: CPTOH-0603... plz, need help troubleshooting

Yep.

(covers most LG plasma panels made in the past few years... check the PDP50X1/2/3/4 sticker to determine which panel you've got.)

[ngc1068]

Re: HP 50" Plasma TV, Model: CPTOH-0603... plz, need help troubleshooting

Is there a detailed guide on adjusting the voltages before I remove the board for mailing to ya?

[capkid]

Re: HP 50" Plasma TV, Model: CPTOH-0603... plz, need help troubleshooting

Yep, that's mal-discharge. The good thing is that it doesn't go away when the panel warms. If that were the case, you'd be looking at a panel problem.

[ngc1068]

Re: HP 50" Plasma TV, Model: CPTOH-0603... plz, need help troubleshooting

Like Tom mentioned, a lot of these LGs need the control boards reprogrammed after the Y-Sus or Z-Sus is replaced to get rid of the mal-discharge. The pixel firing timing gets thrown off by the new parts. I have the LG jig that's used to program the control boards:

https://www.badcaps.net/forum/showth...=mal-discharge

https://www.badcaps.net/forum/showpo...5&postcount=77

Can you post a pic of the pad problem?

So just to be sure, here's a closeup video I took of the TV bottom right corner, showing the red snow. Is this what "mal discharge" looks like? Also, the density of the red pixels changes, depending on what is on the screen, but it doesn't appear to change as the TV warms up. Its there the first time you turn it on, and its there no matter how long the TV is on, doesn't get better or worse.

http://www.modschat.com/IMG_3539.MOV

I also included a still image.

[capkid]

Re: HP 50" Plasma TV, Model: CPTOH-0603... plz, need help troubleshooting

Like Tom mentioned, a lot of these LGs need the control boards reprogrammed after the Y-Sus or Z-Sus is replaced to get rid of the mal-discharge. The pixel firing timing gets thrown off by the new parts. I have the LG jig that's used to program the control boards:

https://www.badcaps.net/forum/showth...=mal-discharge

https://www.badcaps.net/forum/showpo...5&postcount=77

Can you post a pic of the pad problem?

[ngc1068]

Re: HP 50" Plasma TV, Model: CPTOH-0603... plz, need help troubleshooting

This is a common issue with this panel, capkid has a repair service (firmware update) I believe...

Firmware ya think? but it didnt have this problem before the failure last week...

I kinda did a crappy job on replacing the FET. I have a broken left wrist, so wife was pulling up the FET as I heated the heat-sink solder, she's a big strong German girl, she peeled the pad off the board with the FET before the solder melted I put the terminals back down on the new FET, but I bet the heatsink it marginally useful, its not staying down. Is the FET heatsink an active terminal for the FET? Could i just ground it with a homemade heatsink? Could this be behind the red pixel sparkling?

[ngc1068]

Re: HP 50" Plasma TV, Model: CPTOH-0603... plz, need help troubleshooting

But you have one less FET on one board? You should replace that to make sure it doesn't fail again.

No, i had ordered a complete new bottom board, so I had my old one. I robbed one good FET from it and replaced the one bad one on the top board.

[tom66]

Re: HP 50" Plasma TV, Model: CPTOH-0603... plz, need help troubleshooting

This is a common issue with this panel, capkid has a repair service (firmware update) I believe...

[ngc1068]

Re: HP 50" Plasma TV, Model: CPTOH-0603... plz, need help troubleshooting

a few red sparkles all over the screen tho...hrmn

[capkid]

Re: HP 50" Plasma TV, Model: CPTOH-0603... plz, need help troubleshooting

I've never seen both the upper and lower boards fail with bad fets. Noted. Nice job on the fix.

[tom66]

Re: HP 50" Plasma TV, Model: CPTOH-0603... plz, need help troubleshooting

But you have one less FET on one board? You should replace that to make sure it doesn't fail again.

[ngc1068]

Re: HP 50" Plasma TV, Model: CPTOH-0603... plz, need help troubleshooting

yay, that did it!!!! its fixed!

[tom66]

Re: HP 50" Plasma TV, Model: CPTOH-0603... plz, need help troubleshooting

That'll do it.

[ngc1068]

Re: HP 50" Plasma TV, Model: CPTOH-0603... plz, need help troubleshooting

yeah, top most FET on upper is bad