Panasonic TC-P50VT20

[ljintexas]

I can hear relay clicking upon power up of set. Immediately gives ten blink code on LED. If I hold power button blinks stop. Any ideas where to find a service manual?

[tw2005]

Re: Panasonic TC-P50VT20

yeah, but first get you a meter and check across Sc2 pins and see if shorted on Sc board, if not short check on SC , Q661 RJP63F3A IGBT ( heatsink with 2 transistors bottom left corner as mounted in TV)and see if that's short, check IC521 for evidence of burn or hole in top, check IC771 resistance centre pin to output side resistance

[tw2005]

Re: Panasonic TC-P50VT20

http://elektrotanya.com/?q=showresul...at2=schematics

Limit 2 per day with no login

[ljintexas]

Re: Panasonic TC-P50VT20

SC2 pins show 1.8M ohms, not shorted. Q661 is good, however, it's twin Q660 is shorted to ground. Visual inspection of IC521 revealed no evidence of burn or hole. Could not find IC771 for the life of me..looked with lit magnifier for 30 minutes. Also found D422 shorted as well as D641 and D642.
Checked SD card slot for any metallic objects and found none.
That is called out in this troubleshooting guide I found as a possibility when ten blinks are evident.
Also, there is no LED lit on SC board during initial startup or afterwards. Also no LED lit on SS board.

[tw2005]

Re: Panasonic TC-P50VT20

yeah, ok . mixed bag of results there. could be on the wrong track, I'm assuming potential Sc failure but no LED lit and 1.8meg on Sc2 is not what I would expect so could be genuine 10 blink elsewhere.meaning SC is ok, difinitely not shorted . Suggests the vsus is not being turned on at all.

With q660 etc, we're just checking across the 3legs to see if short. If you've gone ground to each 3 on Q660 then 1 leg is grounded so will indicate short to gnd. I have a good one here and i get a short to gnd on 1 leg.

With the TO220 package diodes 2 legs are Anode, 1 K cathode so A-A will be short, you'd have to confirm how you're doing it.

probably would not bother with IC771 now,

disconnect Sc2, Sc20, ss11, backprobe p2 or p11 for vsus as it starts up. If no voltage then we'd have to follow the 10 blink flow charts.

[tw2005]

Re: Panasonic TC-P50VT20

If relays click then immediately 10 blink could be A board sub voltages. I'd follow the 10 blink guide in that trainer.

After Power SW ON,F_STB 15V outputs at P6’s pin 9, 15V outputs at P6’s pin 1 before Shutdown?

If the above is true suggests A-board.

i have a feeling if the D board is isolated from the A, it too can trigger panel on. I'd have to see if that's been tried in another VT post .

can't remember off hand.

[ljintexas]

Re: Panasonic TC-P50VT20

Q660 all three legs shorted to ground. Previous owner says that he replaced A Board and SMPS with no change so he returned the boards and reinstalled originals. His wife made him replace tv..hehe

[ljintexas]

Re: Panasonic TC-P50VT20

I will do as you said and disconnect sc2 sc20 ss11..then measure voltage on p2 and p11..are those plugs or pins?

[ljintexas]

Re: Panasonic TC-P50VT20

Will also check for 15v on P6 pins 9 and 1 before shutdown.

[tw2005]

Re: Panasonic TC-P50VT20

I will do as you said and disconnect sc2 sc20 ss11..then measure voltage on p2 and p11..are those plugs or pins?

either one, that's the 2 power leads from the P board to either ss or sc for Vsus so with the cable removed it'll be pins, with cable connected, I guess the SC or SS end will be a socket.

[ljintexas]

Re: Panasonic TC-P50VT20

I have Vsus of 208 volts going to both SC and SS unplugged from both boards.
P6 pin 1 I have 15.9volts..PIN 9 I get 0volts. if I plug in SC and SS 0 volts at Sc2

[ljintexas]

Re: Panasonic TC-P50VT20

When I unplug harness from A board, I have 15.9 v leaving pin9 of P board. This would sugest that the A board is drawing the voltage down.

[ljintexas]

Re: Panasonic TC-P50VT20

I also have 15.9 volts on pin 7 of P6. Looking more like A board. Your thoughts?

[tw2005]

Re: Panasonic TC-P50VT20

have to think but this is somewhat interesting. Would suggest vsus is being shorted. measure resistance across SS pins at SS11 pin 1 - pin 3 (Vsus), might as well measure pin 3-pin 4 15V.

I don't think we should jump for the A board yet

[tw2005]

Re: Panasonic TC-P50VT20

When I unplug harness from A board, I have 15.9 v leaving pin9 of P board. This would sugest that the A board is drawing the voltage down.

leave harness off and check resistance on A6, pin 6,7 or 8 - gnd.
i think I need to brush up on the f15V section though, I'm more curious about vsus at this stage.

[tw2005]

Re: Panasonic TC-P50VT20

out of curiosity, when you fired it up with sc2,ss1,sc20 removed, what blink code did it shutdown with?

I know reading your original 10 blink at plugin implies F15v or related short on sub 9v or sub 5v but the no vsus with ss/sc then reappearance with those isolated suggests something wrong there too

[ljintexas]

Re: Panasonic TC-P50VT20

I will measure resistance of pins on A6..I assume this is the socket on the A Board? Going to my real job now should have more info later today. will re-enact the condition with the sustains unplugged and observe what led code I get. Will also re-enact Vsus without harnesses plugged in and then with plugged in.
Thanks for taking the time to assist. I appreciate your help Tw

LJ

[tw2005]

Re: Panasonic TC-P50VT20

I'll do my best, never touched the Vt series but a lot can be correlated back to the standard FHD G20. I may be going about this the long way but I'd rather have a full feel of it all. was this your own TV and it quit or a repair job? Any history on what happened , like died after a storm or just normal use?

I'll be going to work when your coming back by the sounds of it, 1122pm here.

yeah , at the A board end since you feel the F15 is not there and suspect A board bringing it down that would suggest short on the A

[ljintexas]

Re: Panasonic TC-P50VT20

Bought it as a non working unit...from original owner. From what he said, it exhibited signs of coming on more slowly than normal in the weeks before it puked..then did not come on at all.

[ljintexas]

Re: Panasonic TC-P50VT20

Also said that when it failed was not around any stormy periods as in lightning. He ran it on a UPS with surge suppression.
I do that on my more expensive larger sets.