Panasonic tc-42px14 faulty sc board 7 blinks

[tw2005]

Hi I'm working on a TC-42PX14,(TH-P42X14A Australia) FAULTY SC BOARD, 7 BLINKS.

Board TNPA4773. I've been fiddling with it and occasionally it powers up with normal screen although at most a minute or 2.

I think I've narrowed the circuit tripping the cct protection to VAD at -158 to -160.7V.

The specs calls for it to be -180V , cutoffs for the trip -160 and above, -200 and below so I'm pretty confident this is the voltage causing this.

I've looked at the cct diagram but I don't know where to start.

I'm thinking MIP9L02MBS. The adj trimmer makes little to no difference to the output.

Anyone attempted component level repairs on SC boards or have any tips?

Thanks

[tw2005]

Re: Panasonic tc-42px14 faulty sc board 7 blinks

Ok, I bypassed the SOS7 line and the set turned on. To the naked eye, the display appeared normal and quite good.
So I checked all the voltages now that I had it staying on. (specs in brackets)
Vsus TPVSUS (SS) 187.2 (187)

Ve TPVE (SS) 124.8 (125)

Vset TPVSET (SC) 290.5 (290V ± 9V Fixed)

Vad TPVAD (SC) -153.5 (-180V ± 2V)

Vscn TPVSCN (SC) -56 (GND_base : - 35V ± 6V)

Vda TPVDA (P) 60 (60V + 1V,)

So it looks like I'm back to my original conclusion of VAD gen being bad.

Can MIP9L02MBS,MIP3900MSSCF,C0ZBZ0001324(M81707FP) be sourced ?

I know I'm guessing that one of these of these is at fault. Both VAD & VSCN are out by the about the same value which has me curious so more investigation required I think.

Ok, To test set with any of the SU or SD boards disconnected there is a White 2 pin connecter, SC50 located bottom left hand corner.

Jumper these pins and the set will fire up as normal.

As far as my results were for re-checking the Voltages, no real difference, VAD was -150V

[tw2005]

Re: Panasonic tc-42px14 faulty sc board 7 blinks

Forgot to post for the final result on this but ultimately replacement of SC board fixed this.