Panasonic th-p50v20a - 4 blinks (sos4)

[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

[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.

[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)

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)

Dunno... could simply be board flex.

[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)

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

[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)

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)

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)

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)

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)

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)

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.

[tw2005]

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

Well, up to my usual dodgey tricks. Just disabled SOS6 return to the "A" board and she's up and running. Service manual seems to have little or no voltage info.

i'll measure VAD which to chassis was nearly 200V. I may have a quick look at my P42X14A fault finding and see how it compares.

These SC boards must have some crazy bit failing to be able to still work and not burn up.

false detect?

OH, and I've earthed the SOS6 return which was sending about 4.4V. Will this destroy anything?

[tw2005]

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

Well boards arrived and it looks like a pig in a poke. TV still not working and now SOS6.

I guess a lost gamble. Hard to believe 2 SC board failures but replacement has no shorted fets at least.

Followed the recommended fault tree, 15V & 5V supplied at SC board. Isolated SC20 that feeds to the "A" board and C10 on the "C1" board and faults goes to SOS8.

According to the Tree, end result Replace SC board.

I'm thinking maybe component level canibalisation and getting one board good.

Any suggestions?

Still have another board coming from different vendor.

These are different revisions to my original but I still think they'll work.

Original was AF, just Tried an AP and I think the next could be AW.

Stay tuned for more giggles at my attempt to fix this.

[tw2005]

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

no just one is shorted.the rest are in paralell to it.pull em all and let the dmm sort em out.

What? I have 7 pulled components already out and all dead short. What's left is no longer shorted.

[kc8adu]

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

no just one is shorted.the rest are in paralell to it.pull em all and let the dmm sort em out.

[tw2005]

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

So yep... they're all dead short. Something real bad must have happened. I don't know what, it might turn out better to replace the whole board.

Chicken. Where's your spirit? Dunno, I was told they were watching it and it just shutdown.

I just wish I could work out the specs but I have been lucky and a guy in the US is a liquidator with a pile of these New. Got a complete suite of boards for $115 AUD although only just ordered so won't count my chickens yet.

Obviously the main is no good here but hoping the rest matches up ok. Same panel but different SC & SS revisions but hopeful it will work.

No suggestions on what the part numbers mean for the dead components?

I've got a SC from a 42" but different component although very similar design layout.

So tempted to take pot luck with swapping the transistors but no specs so very risky.

[tom66]

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

So yep... they're all dead short. Something real bad must have happened. I don't know what, it might turn out better to replace the whole board.