A guide to fixing/troubleshooting some common plasma TV problems

[MadTogger]

Re: A guide to fixing/troubleshooting some common plasma TV problems

You got test patterns, but they were clear, even the gradient ones? (Press red once each time to step through the available patterns.)

Yep, got the test patterns, all the solid colours red, green & blue then grey then red, green & blue gradients that appeared on a 45 degree angle.

Apart from the angle of the gradients, which I suppose is meant to be that way, there was no distortion.

Regards..,

[tom66]

Re: A guide to fixing/troubleshooting some common plasma TV problems

The problem is on the A board for sure then. Replacement is probably the only option but before you replace try this.

This will wipe all user settings and any calibration settings, as well as Panasonic owner ID. (Don't tell nefarious individuals... I don't know if Panasonic fixed this in later models but it wipes it from my 2008 model.)

Hold VOL- on the TV.
Press MENU on the remote.
After some time, the diagnostics page appears.
Turn off the TV by unplugging it.
Turn the TV back on.

The TV should be back in the shipping condition, you will have to retune and set up everything again. (But you'll have to do the same for a new A board, too.)

[MadTogger]

Re: A guide to fixing/troubleshooting some common plasma TV problems

The problem is on the A board for sure then. Replacement is probably the only option but before you replace try this.

This will wipe all user settings and any calibration settings, as well as Panasonic owner ID. (Don't tell nefarious individuals... I don't know if Panasonic fixed this in later models but it wipes it from my 2008 model.)

Hold VOL- on the TV.
Press MENU on the remote.
After some time, the diagnostics page appears.
Turn off the TV by unplugging it.
Turn the TV back on.

The TV should be back in the shipping condition, you will have to retune and set up everything again. (But you'll have to do the same for a new A board, too.)

Thanks, I'll give that a try.

Just out of interest, what does the A board do then?

Regards..,

[tom66]

Re: A guide to fixing/troubleshooting some common plasma TV problems

The A board is where the video inputs come in. They are converted to digital signals (if they are analog inputs) then processed (scaling, smoothing, noise reduction, contrast, brightness) then converted to a format suitable for driving the plasma panel. The A board also decodes audio and drives the loudspeakers, and it handles the processing of the user inputs and remote control, generating the menus. It's sort of like the TV's motherboard.

[George1945]

Re: A guide to fixing/troubleshooting some common plasma TV problems

I have an LG 42" Model 42PC1DG-AA Plasma TV which I bought in August 2006. Recently at start up both the sound and picture as I describe 'snap, crackles and pops'. The pixellation breaks in small horizontal bands in changing areas of the screen and at the same time the sound interrupts or for a short period of a couple of seconds is absent. After about 5-10 minutes as the TV presumably warms up the problem gradually goes until a excellent reception is received. The signal strength is excellent. Anyone got any comments - could it be internal tuner problem???

[MadTogger]

Re: A guide to fixing/troubleshooting some common plasma TV problems

Thanks, I'll give that a try.

Just out of interest, what does the A board do then?

Regards..,

OK, I tried this reset procedure and nothing has changed.

I did notice that when the service menu was displayed, all the checks down the left hand side said 'OK' if that means anything.

Regards..,

[tom66]

Re: A guide to fixing/troubleshooting some common plasma TV problems

I would suggest an A board replacement is necessary then.

[tom66]

Re: A guide to fixing/troubleshooting some common plasma TV problems

I have an LG 42" Model 42PC1DG-AA Plasma TV which I bought in August 2006. Recently at start up both the sound and picture as I describe 'snap, crackles and pops'. The pixellation breaks in small horizontal bands in changing areas of the screen and at the same time the sound interrupts or for a short period of a couple of seconds is absent. After about 5-10 minutes as the TV presumably warms up the problem gradually goes until a excellent reception is received. The signal strength is excellent. Anyone got any comments - could it be internal tuner problem???

Sounds a lot like a weak digital tuner signal. Check antenna connection for crimping and stress. Ensure antenna connector on TV end is not loose. Check and/or replace antenna cable.

[George1945]

Re: A guide to fixing/troubleshooting some common plasma TV problems

Thanks for reply. Checked by borrowing another TV to same antenna connection and cable (cable is new) - borrowed TV clear as a bell no pixel problems.
The warming up aspect is confusing as this implies something to do with TV (especially since borrowed TV OK).
Any other comments?

[tw2005]

Re: A guide to fixing/troubleshooting some common plasma TV problems

Thanks for reply. Checked by borrowing another TV to same antenna connection and cable (cable is new) - borrowed TV clear as a bell no pixel problems.
The warming up aspect is confusing as this implies something to do with TV (especially since borrowed TV OK).
Any other comments?

I think there's potentially a few possible scenarios here.

1. Signal

2. Badcaps/dirty power although i would also expect the TV to lock up and not be controllable.

keep in mind an overstrength signal will produce the same symptoms as a weak signal.
Was anything changed about the same time you first encounter this?
antenna,leads, signal amplifier,?

Can your TV display the signal strength as an option in the menus?
If so, what does it show when it faults and when it works ok?

Is it maxxed out at 100% ?
If your Tv shows signal quality as well, is it good or bad?
Is this happening all channels or only some?
Is there a signal booster on/off feature in the menu? (my 50PX5D did)

Tuner sensitivity will vary between models and brands?

Recently, i had full strength, condition was poor( in the red) no picture, pixelation,freezing and no sound, all channels.

just had new antenna, masthead amp and wall socket replaced after lightning but configuration was the same.

Inside I had another splitter/booster but on low. Signal was over strength, maxxed out on all channels, quality was poor, (red) panasonic Plasmas .

Shutdown the inside amp and everything was back to normal, full strength and quality.

Avoid cheap and nasty no name flyleads, I had one and the signal loss was rediculous and it was new.

[anno]

Re: A guide to fixing/troubleshooting some common plasma TV problems

can you explain what all the boards in plasma tv do?

[tom66]

Re: A guide to fixing/troubleshooting some common plasma TV problems

I've answered this before
https://www.badcaps.net/forum/showthread.php?t=28268

SC = Y-sustain/Y-main
SU/SD = Y-buffers
SS = Z-sustain
C = X board or E/F/G/H boards

[George1945]

Re: A guide to fixing/troubleshooting some common plasma TV problems

tw2005 and tom66
Thanks for all the comments.
In short signal from antenna at wall socket is good. Cable from wall to antenna feed at TV new and good quality (quality antenna less than 3 ys old).
Problem is on all channels more or less the same - some channels like 10 slightly worse and SBS really bad but retuned SBS to new channels in this campaign of retune Australia and it is slightly the best.
TV has signal strength in Menu and best (even with Booster is abt 80-90% - no change when Booster turned off even tho signal may drop to say 60-70%). Worst channels are 55-65% even with Booster.
Checked cannections and everything seems tight.
Keeps coming back to why when TV first turned on 'snap, crackle and pop' and after perhaps 5-10 minutes excellent reception, picture etc.
Spoke to LG Support - no ideas except to book a Tech to come and have a look for abt $85. Done that so I guess I will find out what the pain will be ($200 or less to fix TV or $1000 for new one) and keep this as spare.
Any other ideas - appreciate any feedback.

[George1945]

Re: A guide to fixing/troubleshooting some common plasma TV problems

tw2005 and tom66
Feedback on visit by LG tech. Turned out to be low voltage caps were almost burnt out. Replaced about 6 (I think) - all other caps good. Cost $350 incl fee for assessment ($89). Marginal but went for repairs. Problem gone.
Thanks for comments.

[tw2005]

Re: A guide to fixing/troubleshooting some common plasma TV problems

tw2005 and tom66
Feedback on visit by LG tech. Turned out to be low voltage caps were almost burnt out. Replaced about 6 (I think) - all other caps good. Cost $350 incl fee for assessment ($89). Marginal but went for repairs. Problem gone.
Thanks for comments.

I was thinking along those lines after your last reply but too hard to advise from there as I figured it was not something you were going to tackle yourself. Was it the power supply or the tuner board? Big $$ investment but if it's fixed and your happy that's all that matters.

[George1945]

Re: A guide to fixing/troubleshooting some common plasma TV problems

tw2005
Power supply as I recall. It was a toss up but as I was spending $89 to find out what was wrong and price to fix and he could do it right then and there, I thought 'what the hell, only $260 more whereas the option I mentioned was $200 to fix so???? Only hope the gamble pays off for at least a couple of years. Anyway as you said 'As long as I am happy' and he adjusted the 'leaking' pixels (red dots in top LH corner) to almost nothing whilst he was here.
Thanks again.

[tom66]

Re: A guide to fixing/troubleshooting some common plasma TV problems

To be honest $350 to fix a 42" 720p plasma TV when you can buy a new one for less than $400 seems excessive to me.

[mph8783]

Re: A guide to fixing/troubleshooting some common plasma TV problems

Hi,

I'm struggeling to narrow down the fault with my samsung 50" plasma - and any help is appreciated!.

It is a PS50C96HDX/XEU built in 2007.

I was sat watching it when all of a sudden the picture disappeared. There was no bang, smoke or anything else and the TV sound and remote continued to function.
The way the picture went off was more like the broadcasters satallite link failed but alas it was the TV.

I have checked all PSU rails (except the -192V Vsc as I cant find where it lives) and all fuses. There are no bulging caps, black components or other suspect parts.

The screen is completely black, no glow or snow.

I suspect it is the X or Y main boards but as the service manual is lacking schematics or any other usefull fault diagnostics not too sure how to isolate which one it is.
However the y-main board doesnt appear to have anything more than 14V on any of it's FET outputs (despite 207V going in) - could it be this or just because I am testing with no input picture and a DVM?
The only other suspect board would be the logic board but im not sure if this has the capability to disable the drive voltages or not.

I would prefer to trace to a component if possible, rather than spend lots on new board.

Any ideas?

[tom66]

Re: A guide to fixing/troubleshooting some common plasma TV problems

The way the picture went off was more like the broadcasters satallite link failed but alas it was the TV.

What do you mean by this? Picture went black, or did it break up?

[mph8783]

Re: A guide to fixing/troubleshooting some common plasma TV problems

It didn't go off cleanly like when you power off but deteriorated over just 1 or 2 frames and has been black ever since.