Panasonic TC-P42X1 Plasma 12 Blinks

[kevinm34232]

In standby no blinks. When power button pressed, clicks then goes to 12 blinks which should indicate:

(The operation of the audio power amplifier IC2109 is monitored. If the audio outputcircuit develops a short to ground, a high is output to pin 37 of the MPU (IC1100), triggering a SOS condition. The power LED blinks 12 times)

However I noticed no 15V present at pin heading to audio amp.

On power board I have
+5V(STB) at pin 5 of P7 and
Pins 7&9 of P6 has +FSTB+15V

But no other 5V and 15V present.. Any thoughts?

[kevinm34232]

Re: Panasonic TC-P42X1 Plasma 12 Blinks

Hey before I order new PS board can someone tell me how to isolate SC/SD/SU on this 2009 model too see if set stays on?

[kevinm34232]

Re: Panasonic TC-P42X1 Plasma 12 Blinks

Well I dug in deeper and I did find a short on one channel of Audio Amp IC2109 and after isolating that I now have a 2 blink code for missing 15V. So it seems maybe one problem caused another. Is there a common problem for 2 blinks? I couldn't find anything obvious.

I have the FSTB +15V but not the others, so how do I determine A Board or PS board, is there a PS-ON equivalent from the A Board that turns on the other 15V lines?

[tom66]

Re: Panasonic TC-P42X1 Plasma 12 Blinks

2 blinks can be caused by a shorted other rail (Vsus/Vda), which will cause the 15V to be shut down after a few seconds.
If the amplifier IC has a short on one channel, it probably has other faults too, so you'd need to completely isolate it to be sure.

[tw2005]

Re: Panasonic TC-P42X1 Plasma 12 Blinks

here's some flowcharts.

[kevinm34232]

Re: Panasonic TC-P42X1 Plasma 12 Blinks

The 15VP and 15VAudio never comes up though, there is a FSTB+15V that comes up with the standby but I think the other 15V comes from somewhere else and is turned on later?

[tom66]

Re: Panasonic TC-P42X1 Plasma 12 Blinks

They are MOSFET-switched from same 15V usually, so it could be a short on there is dragging FSTBY 15V down.

[kevinm34232]

Re: Panasonic TC-P42X1 Plasma 12 Blinks

On the flowchart it says check pin 1 on P6, which if you look at the pic below is +15V(SND). There is never any voltage there from plugging into AC to the blinking SOS.

And that looks like it comes from D705 not where the FSTB+15V comes from right? So I wasn't sure if that had to be 'turned on' by the A board, because I basically get no voltages other than the 5 and 15 STBY.

Oh another thing is I was not getting any voltage to VCC pin of IC301.

[tom66]

Re: Panasonic TC-P42X1 Plasma 12 Blinks

Can you see transistor Q301 on power board? What about IC302?

[kevinm34232]

Re: Panasonic TC-P42X1 Plasma 12 Blinks

Yes here are some pics, those are on bottom of board.

Last pic from SM, not sure if you were looking at it but I have the 21V from IC101 at the one leg of Q301

[tom66]

Re: Panasonic TC-P42X1 Plasma 12 Blinks

This is going to be awkward. Can you check the voltage across the primary side ("HOT" side) of IC302 as it turns on and switches to the blink code? It might work best to solder wires to the terminals and measure those.

[kevinm34232]

Re: Panasonic TC-P42X1 Plasma 12 Blinks

It's 21V. I have the board upside down on a towel with just the connections to the main board.

So basically I have 21V on those 2 pins of Q301, but 0v on the pin going to VCC of IC301.

[tom66]

Re: Panasonic TC-P42X1 Plasma 12 Blinks

IC302 is not being turned on, then. Check across the secondary, expecting near-zero. (<1V threshold.)

[kevinm34232]

Re: Panasonic TC-P42X1 Plasma 12 Blinks

Yes 0.1V across secondary side. What would happen if IC302 was turning on, voltage would go low across HOT side?

I tried to trace, looks like that signal is coming from pin 12 of IC603 Power Micom (Vreso_ON_L)?

[tom66]

Re: Panasonic TC-P42X1 Plasma 12 Blinks

OK, on the secondary of IC302, check the voltage on each end with respect to ground.
If both ends are near 5V, the OPTO is not being commanded to turn on for some reason.

[kevinm34232]

Re: Panasonic TC-P42X1 Plasma 12 Blinks

Yep both legs are around 5V when first plugged in, AND when switched on there is no change up to the 2 blinks...

So you think this is controlled by IC603?

Can we conclude yet going back to post 5, if there is no 15V at pin 1 of connector P6, that this is power supply issue and not an A board issue????

[tw2005]

Re: Panasonic TC-P42X1 Plasma 12 Blinks

So very first step, check resistance pin 1 P6, what happened there?

This could be worth a go, disconnect SC2,SS11,P35,3 white ribbons at A and powerup.

[kevinm34232]

Re: Panasonic TC-P42X1 Plasma 12 Blinks

No short, and disconnecting all of those cables still gives 2 blinks.

[tom66]

Re: Panasonic TC-P42X1 Plasma 12 Blinks

Try checking voltage across secondary of IC600. It's the AC DET optocoupler.
The power MCU controls all power sequencing: it is not turning on the 15V for some reason, but it is not known why yet.
It could just as well be a main board fault due to incorrect PSON output or sequencing (bad firmware/EEPROM/config etc.)

[kevinm34232]

Re: Panasonic TC-P42X1 Plasma 12 Blinks

IC600 has about 1.2v across secondary side thru startup to blinking.