Panasonic Plasma TH-42PZ77U 12 Blinks

[Sevenqi]

This was the first time I repaired a 12 Bilinks Panasonic TV, symptoms: PLug in the wall, two clicks, after a while then one click. Pressed power button in the TV or in the remote control, heard click, but gave 12 blinks, not power on, the cooling fans ran a second or two, then stopped.

The error code in the service manual mentions this is the audio processor propblem, check the H board.

What I tried was to disconntect both speakers, no change. Disconnect the cable to the side input board, no changes. Disconnect the power cables from power supply to the H board, gave 10 blinks.

I suspected the H Board TNPA4360 failed, ordered one and replaced it, unluckily, the problem is still the same. I could see the LED of the optical output jack lite up then off as the tv shut off.

Anyone experienced the 12 blinks for Panasonic Plasma?

[tom66]

Re: Panasonic Plasma TH-42PZ77U 12 Blinks

If you can trace where the 12 blink signal is coming from... you might be able to find the source.


Page 75 SOUND_SOS senses SOUND+15V and AMP FAULT. If SOUND+15V goes LOW, then a fault will be signalled.

If TP2037 on H board goes HIGH (+15V) the sound has a fault.
This signal appears on pin 39 of connector H3 too.

[Sevenqi]

Re: Panasonic Plasma TH-42PZ77U 12 Blinks

I checked the TP2037, 2.67V, and I installed back my original board, is 2.71V. Not sure if voltage is high or low, from Tom66's comment, 15V is high, so 2.67 is low.
I also checked the voltage from the power supply, it's 15.75v, normal.
Is it possible two boards fault at the same part ? or the fault I from other boards?

[tom66]

Re: Panasonic Plasma TH-42PZ77U 12 Blinks

2.7V would be high enough to trigger it. What you can try is take a 100 ohm resistor to ground and force SOUND SOS low. Unplug speakers while you do this. Check if there are further abnormalities.

[Sevenqi]

Re: Panasonic Plasma TH-42PZ77U 12 Blinks

I tried to short the check point with a 100ohm resistor, still not power on, but gave 1 blink, mainboard problem?
I accidently unplug the connector from the mainboard to the side input board, the tv power on and works! (I think this was the video/audio input board shorted, no time to check it).
But unfortunately this TV has another big issue: There are 5 vertical bars on the lower of the screen, and there are many very thin vertical lines, most lines on the lower screen, some on the upper screen.
I have no mood to go ahead to fix it, the 4 of the C buffer boards are bad, or even the panel is bad.

[tom66]

Re: Panasonic Plasma TH-42PZ77U 12 Blinks

Big bars: if there is NOTHING in those bars, it is quite likely that they are just loose connections or bad C board. But if there is something in them, then it can be a bad plasma panel.