Plasma TVs repair:Panasonic 50"ST50,Samsung 64"F8500

[Erik Masters]

Hi all

I need some help.
I have 2 plasma tvs that needs repair.

1st tv is Panasonic ST50 50inch 2012 model:
It have a issue with lots of pink grain on any bright content and white especially. Anything near full screen white looks very bad,pink/magenta with lots of grain,flickering and ghosting from image retention.On dark content tv looks great,amost perfect.
Also power supply is very loud on any brighter content.
This fault happened overnight,tv worked perfectly before that.

2nd tv is Samsung F8500 64inch:
TV have a issue where third of screen is black,while the rest of the screen looks normal.

Are these TVs repairable with board replacement or something? Both are still capable of great picture and it would be huge waste to throw them off.
These TVs dont need to be perfect,I just want something decent for my parents.
Both TVs are EU models.

Thanks.

[awyatt2]

Re: Plasma TVs repair:Panasonic 50"ST50,Samsung 64"F8500

the Panasonic could be ss or sc board related. unsure on that model Samsung but there should be address boards near the bottom of the screen. and it also could be damage to the board from liquid. the older sammys had replaceable boards newer may be made onto the cables. I have the service manual on the panny if you need it.

[Erik Masters]

Re: Plasma TVs repair:Panasonic 50"ST50,Samsung 64"F8500

I still own 65"ST50 in excellent condition and I have service manual as well.
But it's barely of any use to me,I'm not that good with repair,lol.
But I should be able to swap boards.

I need solution for 50"ST50 at least 'cause my father loves it.
Like I said,it don't need to be perfect,just to reduce that purple rain somewhat.
So which board ss,sc or rather both?

[awyatt2]

Re: Plasma TVs repair:Panasonic 50"ST50,Samsung 64"F8500

could be either or both, look in the ser manual under picture distortion, yours isn't as bad but still its there. are you capable of checking the voltages on the vs and va? they may be too low. but the service manual only list the boards and in your case either or both.

[Erik Masters]

Re: Plasma TVs repair:Panasonic 50"ST50,Samsung 64"F8500

That purple rain is pretty severe on white and I think it's slowly getting worse.
And I can't check the voltages.
I don't have the meter and repairmen in my area refuse to repair tvs.

I'll rather swap them both to be sure.
And what about PSU? Like I mentioned,it's very audible compared to my 65"ST50.
Won't be that a problem? So those boards wont pop again,when I swap them?

[awyatt2]

Re: Plasma TVs repair:Panasonic 50"ST50,Samsung 64"F8500

power supply is doubtful as its working now, the samsung has three buffers at the bottom of the screen I found a picture of a pn64f8500 with the back off. they are e,f,g, buffers it will be the one directly under the black part of the screen. I don't have the same tv to tell how they come apart. but they do in three sections. now back to noisy ps I assume you mean static and snow in the picture? if so its probably dragging down by the bad boards. still you may need to adjust va and vs voltages due to a different board. I have replaced some that were spot on and some way out of spec. there is a sticker on the back of the screen saying the voltages.pick up a decent digital meter in case you get a lot of sparkles or mal-discharge

[awyatt2]

Re: Plasma TVs repair:Panasonic 50"ST50,Samsung 64"F8500

https://www.tvserviceparts.com/Parts...8500AFXZA.html

here is a link to the Samsung parts down the page you will find e buffer,f buffer and g buffer. you didn't give the full model number so I used what you gave and this is the one I found. you would need to check the board numbers as well to make sure they are right. you only need the one directly under the black part of the screen.

[Erik Masters]

Re: Plasma TVs repair:Panasonic 50"ST50,Samsung 64"F8500

Excellent
I'll try that Samsung first,it looks like the best solution and it should really work.
I even contacted decent repairman for tvs,he should help me with those SS/SC boards.
Thank you very much for your help.

[awyatt2]

Re: Plasma TVs repair:Panasonic 50"ST50,Samsung 64"F8500

you might want to have him check esr on caps on ss and sc boards, if he has an esr meter. I have been scolded for saying this but I have fixed at least 4 pannys with bad caps. all were on the sc boards and tv sometimes would work perfectly and others 7 or 8 blinks.

[Erik Masters]

Re: Plasma TVs repair:Panasonic 50"ST50,Samsung 64"F8500

Hi again.
I managed to fix 50ST50 mentioned here,year ago by replacing PSU board.
Now it works perfectly and calibrated it looks great with possibly best light output on late Panasonic plasmas.

But now I'm having another issue,lol And complete opossite of that 50ST50.
My beloved 65ST50 totally degraded in light output over last 7months or so,to the point where it looks like it's in permanent Eco mode and with all dimming options turned off!
I'm aware that many plasmas had pretty big aging issues/contrast loss,but this one is totally worst and looks like some component is failing.And that 50"version is still bright.
Its also affected saturation pretty badly where some scenes are totally washed out no matter what I do.
And also buzzing got lot louder and it's coming from everywhere,but right side from the back is loudest I think.

So is there anything that can be done or should I sell it while it's still working?
Im already planning to buy Oled this year,but first I would want to do something with this TV,otherwise it might bug me forever,lol
Thanks for any help.

[andyb1712]

Re: Plasma TVs repair:Panasonic 50"ST50,Samsung 64"F8500

30 series Panasonic plasmas had issues with screws coming loose on the SC boards, causing them to fail prematurely. Later models like yours didn't suffer this due to a return to split locking washers on the screw. It's worth checking they are all done up tight though as loud buzzing was a typical symptom before the SC board failed.

[Erik Masters]

Re: Plasma TVs repair:Panasonic 50"ST50,Samsung 64"F8500

Hi all

I need some help again,this time with broken TV/board due to a power surge from exploded lightbulb.
As a result no HDMI ports works anymore.
Is there anything I can do to repair TV without replacing mainboard?

TV is again the same plasma mentioned in this thread Panasonic 50ST50 where I already replaced PSU before. cursed one,lol
But I really want to save this TV,it's most balanced from late Panasonic Plasmas IMO: good blacks and very bright for a Panny Plasma without agressive dimming.

Thanks for any help.

[Th3_uN1Qu3]

Re: Plasma TVs repair:Panasonic 50"ST50,Samsung 64"F8500

Sadly I think replacing the main board is the only solution in this case, unless all the HDMI ports are behind the switch IC in which case you may be lucky and just need to replace the HDMI switch. However all boards I've seen have one port wired directly into the CPU - if that's dead, so will all others be as the HDMI part of the processor shorts out.