TH-P50G15A - 6 Blinks- Bad TNPA4782

[Glitcher]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

Did you check if D806 is okay?

[tw2005]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

Finally got some action. blew it up. Q661,660,601, D618 failed. getting a little frustrated I back tracked and started putting a couple of old parts I had swapped out back in. neither did any damage previous but then IC521 was shorted when they were in. I'm lookig at IC691, and IC561,562

Anyway after puttung IC691 (NAND) back it went off like a fire cracker, I think that was D618. Before this MID was back to about 50v from being 145V. Still not right.

What is also interesting is at TPSOS7, if I earth that out it still tripped and I tried putting a meter on it to see and whatever is happening it's too quick for the meter to read but I did see 1.3V . Probing TPSOS6 however is normal 4.4V initial then drops off to 0.

I've run this up and managed to get it to stay on with just the A, P although this does have a D board and D20,31,32 were removed so I'm pretty sure that proves it's not a misdetect oor another board(D board)
Not sure what to make of it all unless D618 was bad and I just missed it.

[tw2005]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

Way too high, should be near exact 1/2 Vsus.

Looks like energy's getting into the ER caps but not being extracted; Check IGBTs and FET drivers for lower ERC path.

just found bad IC521, now 7, and no life in the panel at all. Had to use m81737FP in lieu of 81707

[tom66]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

Registers 145.7 V at shutdown

Way too high, should be near exact 1/2 Vsus.

Looks like energy's getting into the ER caps but not being extracted; Check IGBTs and FET drivers for lower ERC path.

[tw2005]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

not making much progress but discovered FET driver IC521 is bad. M81707FP

Don't have one, anyone tried M81737FP in it's place?

I have and now 7 blinks, not a glimmer in the panel now

[tw2005]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

Interesting, that TNPA4782 board i was working on today is doing this exact same thing! I replaced all the shorted and suspected bad parts on it. Plugged it in and it'll turn on, flash on the screen for a second and then shut off and back to 6 blinks. Rechecked the parts replaced and no shorts or any blown parts to be seen. I also replaced rjp6065 with a rjp63f3a.

Well, hurry up and work it out. I would not mind a hand for a change, really pressed for time.

Interesting this G15 has an ethernet port so must have similar features to my V20(maybe)

[tw2005]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

What's MID voltage? (across the bank of blue poly caps on the SC.)

Registers 145.7 V at shutdown

[Glitcher]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

Interesting, that TNPA4782 board i was working on today is doing this exact same thing! I replaced all the shorted and suspected bad parts on it. Plugged it in and it'll turn on, flash on the screen for a second and then shut off and back to 6 blinks. Rechecked the parts replaced and no shorts or any blown parts to be seen. I also replaced rjp6065 with a rjp63f3a.

[tom66]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

What's MID voltage? (across the bank of blue poly caps on the SC.)

[tw2005]

Well, I've finally got an opportunity to have a crack at a TV with the TNPA4782.

6 Blink, SOS 6. Expectations are SC board with blown IGBTs everywhere.

At first inspection and I'm rushing , i find a lot of surface corrosion on parts and the SC2 terminal is not healthy or it is a healthy green if it were a plant.

The board has scorch marks from arcing under the connector and with the SC2 lead removed , more tracking and arcing marks.

Cool, I'm thinking clean this up and maybe get lucky - no, still 6 blinks

So go over it more thoroughly and find Q661 shorted C-E, D673,674 shorted. I went with the diodes which are a pain to desolder and was wrong . Ended up being Q661 C-E short.

Q661 RJP6065, I've used a RJP63F3A which is the newer version . replaced Q818 2SK3018, Q702 2PD601 was short, IC773 TC7SH14F was shorted Vcc-gnd(41ohms),

Fired it up, still shuts down 6 blink but nothing blows. panel very briefly energises.

replaced Q701 MMBTA92, Q876 2PD601, IC724,725 78L05

No change, still 6 blink. Tried SC50 bypass, - same

So far voltages are spot on

TPVsus 198.5V
TPVscn -41.1 (- 40V ± 6V)
TPVAD -186.2 (- 185V ± 2V)
TPVe 135.2
There is no Vset cct on this