View Full Version : CPTOH-0602 blank screen


miniman82
09-05-2016, 10:48 PM
So I came across this plasma display at the recycling place, and figured I'd have a go at repairing it. Both sustain boards were shot of course, so Y got an NOS Sanyo IPM, and I was able to salvage the Z board IPM by replacing the on board IGBT's with through hole devices. There's a video on you tube showing how this is done.

It powers up now and gets a dull light on screen, but it acts like it doesn't have any input. The buttons on the side don't bring up any of the menus like they should either, so I'm thinking dead main board?

mstaton
09-06-2016, 08:39 AM
Double check the ribbon cables going to the boards. Sometimes one gets forgotten

miniman82
09-06-2016, 05:08 PM
Good call! I didn't even think to look since it was in such good shape physically, there's a board buried under the two main ones I bet if there's something loose it's gonna be right there.

miniman82
10-10-2016, 07:15 PM
Excellent news, it was in fact a loose cable going to the video output board! You could tell where the silicone that was supposed to be holding it in place had broken, allowing it to work its way out of the socket. I hit the power switch after reseating the cable, and was greeted by the welcome screen.


In reality this shot looked perfect, it's grainy due to cell phone camera moire.

http://miniman82.4t.com/images/HP%20Plasma/image1.JPG




After it ran with HDMI input for a few minutes though, the image appeared a little grainy so I'm thinking the main board is past it's prime? Here's an actual off screen shot.

http://miniman82.4t.com/images/HP%20Plasma/image2.JPG

Very hard to see what I'm talking about, but what you can see is a bit of a shadow that looks like welcome screen burn in. It's not the screen itself though, it looks a bit like a mistuned station on a CRT TV does with video noise and whatnot. Doesn't happen with any of the menus on screen, just actual video. I suppose it's time to scope the power supply for noise and possibly replace some capacitors, but if that's not it I'm probably going to put a new main board in it.

Also, these sustain board heat sinks get insanely hot after only a couple minutes of running. It's a wonder they made it through factory testing without blowing up, it's going to take some serious forced air fan cooling to keep things in check. I hope I can keep it cool enough to live.


Thoughts?

Zenith26kc20
10-19-2016, 04:28 PM
I have a Haier (LG) plasma I run with the back off. The sustain modules will burn your hands they run so hot! I can't imagine how hot they get with the back on!
It is a maximum 720P set that I adopted years ago and it gets little use. If yours is an older model, screen burn was much worse than the later sets. Also, the pixel size is fairly large on mine.
A good winter night TV!