Samsung Plasma PS42C451 no picture, good sound

[dkneyle]

My neighbour reported he just turned it on, had sound, no picture. I can confirm there is no indication of any illumination whatsoever from the screen. All voltages seem to check out OK: Vs, Vscan and Ve.

I replaced the Y-Sus board figuring it would be an easy fix. No change whatsoever.

The telltale LED is happily flashing on the logic board. Audio output is OK.

I feel I'm missing something simple here? All suggestions much appreciated.

[tvtimmy]

Re: Samsung Plasma PS42C451 no picture, good sound

Run the test patterns.

[dkneyle]

Re: Samsung Plasma PS42C451 no picture, good sound

Have placed jumper in position to attempt to run the test patterns. In a darkened room I can see the occasional VERY dim white-wash screen as it runs through its patterns.
All voltages to the Y-Sus board look good (this is a 2nd-hand replacement board that is supposedly good).
We have a good heart beat LED signal, suggesting probably nothing wrong with Y-Sus or X-Sus boards?
I disconnected the X-Sus board and then there is no sign of life from the panel. Heart drops back to about 1 per 5 seconds as you's expect.
I'm at a bit of a loss and need some guidance from a plasma guru.
Do you reckon control board has died?

[R_J]

Re: Samsung Plasma PS42C451 no picture, good sound

I would check the fets on the x-sus, That board looks familiar

[dkneyle]

Re: Samsung Plasma PS42C451 no picture, good sound

Sorry, I'm an idiot. There is a very small power connector going from the Y-Sus board to the z-Board running along the bottom of the screen and I hadn't put it back on.

So test patterns run all OK. Resetting TV with jumper removed I again have sound but no image.

Control board?

[dkneyle]

Re: Samsung Plasma PS42C451 no picture, good sound

From what I've been reading, if the test patterns are OK then the Logic Board will also be OK. Leaving the Mainboard I guess?

[tvtimmy]

Re: Samsung Plasma PS42C451 no picture, good sound

If you have good test patterns, the main board is bad.

[dkneyle]

Re: Samsung Plasma PS42C451 no picture, good sound

Before deciding to seek out a replacement mainboard I did what I should have done first. I reseated the video signal cable between the mainboard and the logic board. I also reseated the mainboard power cable. Everything came good afterwards. I looked carefully through my mag lens at those cables and they looked perfect before I reseated them. Some marker-pen writing on the mainboard suggests it has been changed over previously. I just wonder if there was some grime on the contacts? We've also been having extraordinarily hot weather here in Oz lately. Expansion and contraction might also explain something. Anyway, all going again and post closed!

[tvtimmy]

Re: Samsung Plasma PS42C451 no picture, good sound

Great ending!