Panasonic th-p50v20a - 4 blinks (sos4)

[tw2005]

Re: Panasonic th-p50v20a - 4 blinks (sos4)

Panel Time 2530Hrs.

VAD to chassis gnd -199V.
VAD to VFgnd -70V

TPVSCN to chassis -53V
TPVSCN to VAD 147V

VSUS 203.8V
TPVe 134.9V


This is so different to what I'm used to. No panel sticker for the voltages either?

Need help.

[tom66]

Re: Panasonic th-p50v20a - 4 blinks (sos4)

Most Panny plasmas seem to only require those two adjustable voltages. The others are all fixed. I guess they can manufacture the panel well enough for it not to matter.

[tw2005]

Re: Panasonic th-p50v20a - 4 blinks (sos4)

Ok, It's all sorted now and I reckon this is a good one to save somewhere because I hate replacing boards just because of a $0.20 part.

Just to re-cap.
SOS4 on front panel, PSU SOS
VSUS =0V,
Removed SC board, VSUS 204V, Shutdown , Now SOS7,
Checked original SC board, multiple FETs,IGBT & Diodes dead short killing VSUS.

Ordered replacement SC, supposedly New from smashed TV.
Installed, still not working, now SOS6. Followed SC board tests and isolation confirming SC board faulty.

Disabled SOS6 return to "A" board, TV fired up, checked voltages, appear ok, picture appears ok.
Green LED D583 (D16583) not illuminating. fault tree says replace SC if LED not lit.

Traced SOS6 error detect at IC581(IC16581), measured 107V on anode side of LED, 0V on cathode which is what the comparator uses to check. LED is open cct.

60-151V is spec so 107V is good.

Jumpered D583 on original board across dead D583 on replacement board, LED illuminated, SOS6 return enabled and TV now functioning correctly , no more SOS6!

A bit of additional unecessary work thanks to yet another Ebay Seller of faulty parts but I now have a beautiful FHD internet capable 50" Panasonic.

[tom66]

Re: Panasonic th-p50v20a - 4 blinks (sos4)

Nice! Very nice!

I don't like how they use the LED in series with the voltage monitoring though.

Now I wish I hadn't cracked the panel in the P50G10B

[tw2005]

Re: Panasonic th-p50v20a - 4 blinks (sos4)

Nice! Very nice!

I don't like how they use the LED in series with the voltage monitoring though.

Now I wish I hadn't cracked the panel in the P50G10B

I was not going to bring that up, but yeah that was the exact point I was pointing you too as a possible checkpoint on yours. I was wondering the what ifs on that one.

Glad you liked it. Just shows some of the rediculous weak links that shut the whole show down.

I'm even wondering I should be able to just put a link in place of the led and it still should work?

[tom66]

Re: Panasonic th-p50v20a - 4 blinks (sos4)

You should be able to link it fine... it drops about 2V so won't really influence the error detection threshold. It's semi-useful as a high voltage warning though.

My case was a genuine "SOS6". The VMID was only hitting 55V, minimum 67V. I think it may either have been a bad panel from the start (I recently noticed a tiny chip in the corner which is separate from the main crack I put in it), or a VMID tolerance that was not good enough - perhaps as the panel ages it provides a lower VMID. The VMID is part of the energy recovery circuit which doubles or triples the efficiency of the panel.

I suspect a cracked screen may kill the SC on these tellies! As my SC behaves exactly the same with the bad panel. I'd expect it to be easier to drive a cracked panel (no current due to air isolation instead of plasma gases...) May also explain why the part seems to be made of unobtanium!

[tw2005]

Re: Panasonic th-p50v20a - 4 blinks (sos4)

Arggh, Oh so complex. yeah there's plenty of variables. But just one good area to check though. Fancy spending hundreds on a new board if it was a pissy LED failure. I really don't see the point of it. It's going to shutdown if the voltage is out of range so who cares if there's a pretty LED. I wonder what the average lifespan in hours is for a LED?

Certainly a rare one I reckon. 2.00am, late enough for me.

[tom66]

Re: Panasonic th-p50v20a - 4 blinks (sos4)

LED, typically 20,000-50,000 hours at low current.

[tw2005]

Re: Panasonic th-p50v20a - 4 blinks (sos4)

What are the chances of electrostatic discharge blowing it then you reckon?

The boards were all packed together in layers of newspaper and foam bubbles.

Highly unlikely failure you'd think

[tom66]

Re: Panasonic th-p50v20a - 4 blinks (sos4)

Dunno... could simply be board flex.

[tw2005]

Re: Panasonic th-p50v20a - 4 blinks (sos4)

British board arrived. TNPA5081 Rev: AW TXNSC11VEK50 WORKS perfectly fine too.

original was AF revision

Check out my cool orange 3mm LED sub for the open cct chip LED. (all i could salvage )

[tom66]

Re: Panasonic th-p50v20a - 4 blinks (sos4)

Glad you got it working. Interesting it works fine with AW rev - wouldn't know what the rev code stands for though so some might not work.

[tw2005]

Re: Panasonic th-p50v20a - 4 blinks (sos4)

Glad you got it working. Interesting it works fine with AW rev - wouldn't know what the rev code stands for though so some might not work.

AP revision works too. that's the one in the photo.

[ted_ge]

Re: Panasonic th-p50v20a - 4 blinks (sos4)

I have the 46" version.
Replaced shorted:
q16421, q16422, q16423
q16402
d16865
q16661
After jumped the sc50 (with removed SU and SD buffers) and turned on
q16661 shorted again (with a bang!)
Do you have suggestions as to why?
Thank you for your time