Panasonic TC-P50G10B - flashes 7 times, stuck in standby

[tw2005]

Re: Panasonic TC-P50G10B - flashes 7 times, stuck in standby

What do you think about IC581(IC16581) Volatge error Detect at <67V and 139V or more? What's that monitoring?

[tom66]

Re: Panasonic TC-P50G10B - flashes 7 times, stuck in standby

I guess that's involved in SOS6. In fact, you make a good point - it looks like it might just measure the average voltage going to the panel buffers. If the drive circuit wasn't getting power, it could explain SOS6, because there would be zero average voltage. May explain why disabling SOS7 triggers SOS6. I didn't realise that. Thanks!

[tom66]

Re: Panasonic TC-P50G10B - flashes 7 times, stuck in standby

Here's a picture of the SC and of the suspect failure: a little hybrid module responsible for generating +16V_F along with +32V_F.

[tom66]

Re: Panasonic TC-P50G10B - flashes 7 times, stuck in standby

Hybrid module is fine... just tested it to be sure. But still not getting any good 16V at the error detect circuit.

[tom66]

Re: Panasonic TC-P50G10B - flashes 7 times, stuck in standby

Blue trace is error signal, yellow is 15V power. You can see that the error is causing the 15V to shut down.

[tom66]

Re: Panasonic TC-P50G10B - flashes 7 times, stuck in standby

Shoulda tried it with the buffer connected, it uses the plasma panel to build up energy on the energy recovery caps, without the buffers the 5.9V for the regulator didn't come up, but that's working now, so it must be one of the other four protections. But I feel like I'm pretty close to finding out the problem.

[tw2005]

Re: Panasonic TC-P50G10B - flashes 7 times, stuck in standby

Are you testing with no buffers connected?

[tw2005]

Re: Panasonic TC-P50G10B - flashes 7 times, stuck in standby

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

[tom66]

Re: Panasonic TC-P50G10B - flashes 7 times, stuck in standby

Many thanks for that tip. I'll have to keep that in mind for future. I think the buffers are OK on this one... but I suppose I haven't tested it as it gives 7 blinks with and without them and the error code corresponds possibly to a buffer fault. I'll try it tomorrow when I get some more time. Does it work with one buffer only, or do both need removing?

[tw2005]

Re: Panasonic TC-P50G10B - flashes 7 times, stuck in standby

Many thanks for that tip. I'll have to keep that in mind for future. I think the buffers are OK on this one... but I suppose I haven't tested it as it gives 7 blinks with and without them and the error code corresponds possibly to a buffer fault. I'll try it tomorrow when I get some more time. Does it work with one buffer only, or do both need removing?

You had to ask. Not sure. I disconnected a LG buffer once but forgot to isolate it from the other and it smoked. Lucky it was the bad one so get get a bit nervy about it now. I like to remove them completely out of the set these days.

I'll see if I can find the manual I got the procedure out of. My gut tells me your fault will be on the SC. These time zones are fun. I get up as you hit the sack.

What is it 10:35pm there(7:35am Mon here)

[tom66]

Re: Panasonic TC-P50G10B - flashes 7 times, stuck in standby

22:42 here.

I'll try with both tomorrow. Have run this set with one with no smoke - but still 7 blinks - of course that might mean no sus waveform... Not like the older TX-42PZ70BA. I had that running with just the upper buffer and got half a picture. Makes sense don't know why the newer ones don't support this.

I left my nice fixed 10X probe at home, and my other switchable 10X probes are only 300V rated, so I can't probe the sustain waveform at the moment . I will see if I can borrow a fixed 10X probe rated for at least 500V.

[tw2005]

Re: Panasonic TC-P50G10B - flashes 7 times, stuck in standby

Not this model but 12th Gen which yours is. They even rate the likelyhood of which bits most likely for the SOS7 trigger.



It's the 11th Gen manual i think for the rundown of board isolation. I have it somewhere.

[tw2005]

Re: Panasonic TC-P50G10B - flashes 7 times, stuck in standby

22:42 here.

I'll try with both tomorrow. Have run this set with one with no smoke - but still 7 blinks - of course that might mean no sus waveform... Not like the older TX-42PZ70BA. I had that running with just the upper buffer and got half a picture. Makes sense don't know why the newer ones don't support this.

I left my nice fixed 10X probe at home, and my other switchable 10X probes are only 300V rated, so I can't probe the sustain waveform at the moment . I will see if I can borrow a fixed 10X probe rated for at least 500V.

Any part of those buffers disconnected and I'm pretty sure it won't fire up at all. You have to jumper the SC.

[tom66]

Re: Panasonic TC-P50G10B - flashes 7 times, stuck in standby

Thanks for the link. I've only been working off schematics in the service manual. Didn't consider that there might be a training manual. Plasmas are fun for me to work on though. I love fixing them even if they can be more tricky sometimes (though, you can get lucky...)

[tw2005]

Re: Panasonic TC-P50G10B - flashes 7 times, stuck in standby

Thanks for the link. I've only been working off schematics in the service manual. Didn't consider that there might be a training manual. Plasmas are fun for me to work on though. I love fixing them even if they can be more tricky sometimes (though, you can get lucky...)

The best thing in the Trainers is the extra tips and sometimes the anomalies with some of the fault codes they sometimes find.

Like any self diagnostic function it's a start point not always what the true fault is.

I worked on a system which was pretty smart with its self diagnosis but watching techs order every part listed without doing their own analysis was amusing at times when they still did'nt fix it.

I do find fault find these panasonics tricky at times and complex. Sometimes just bite the bullet and get the board but finding that one component is rewarding.

[tw2005]

Re: Panasonic TC-P50G10B - flashes 7 times, stuck in standby

Ok I think it's this one that goes into the buffer board isolation procedures. Not quite the one I read but I think that jumper connector was added later. This gives individual tests using alligator clips but pretty sure you just need to jumper that connector.

P63. You can download to get the full story

There was also a recommendation not to run for more than 30secs with any board disconnected.

[tw2005]

Re: Panasonic TC-P50G10B - flashes 7 times, stuck in standby

Sure hope you can component level repair the SC board. Can't find them anywhere. makes you wonder if they were a dud.

[tom66]

Re: Panasonic TC-P50G10B - flashes 7 times, stuck in standby

OK, got the thing to do 6 blinks now I've got the buffers fixed on. Still no picture, so I looked elsewhere.

SOS6 simply measures the voltage on the energy recovery caps. This should be between 67V and 139V as you mentioned earlier. It's just about hitting 64V, so it's nearly there... and I suspect if it does hit 67V, then the D board will start liking it and start sustaining the panel allowing ER to rise much higher.

I need to figure out how the ER/MID voltage is generated.

The VSC1 output - the sustain drive - is looking a bit poor; it's only peaking to about 70V, when it should be close to 200V with 290V Vset peak.

[tom66]

Re: Panasonic TC-P50G10B - flashes 7 times, stuck in standby

It looks like the cause may be that the VOH transistor/IGBTs are not firing - none of them are. I need to check how gate drive is generated for these IGBTs. I think the devices themselves are OK but I am not certain yet.

SS appears to work for a subfield as it is generating what looks to be a reasonable wave.

[tw2005]

Re: Panasonic TC-P50G10B - flashes 7 times, stuck in standby

It looks like the cause may be that the VOH transistor/IGBTs are not firing - none of them are. I need to check how gate drive is generated for these IGBTs. I think the devices themselves are OK but I am not certain yet.

SS appears to work for a subfield as it is generating what looks to be a reasonable wave.

The fact they don't fire would that simply be because the protection cct is activated?