Panasonic 42' Plasma TC-P42x3

[seppuku]

Without too much back story; my tv experienced a power surge and no longer works.

Immediately upon plugging in the TV I can hear a 'click' but there are no lights or any other obvious indication that the tv is working.

I've taken the back off the tv and tested the two fuses right downstream of the power supply and the resistance reads '0 ohms' and there is no sign of damage that I can detect.

This is the extent of my very limited trouble shooting skills, so any direction is greatly appreciated. I'm looking for someone to help me troubleshoot individual components on the psu in hopes that I can replace a few inexpensive components to get this guy back in working condition, as there is a small margin to just buying a new tv.

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[tom66]

Re: Panasonic 42' Plasma TC-P42x3

Ok, on the power board there's a brown and white cable going to the main video input board (the one with the HDMI and other ports on it.)

Can you get a picture of the connector end? There should be labels.

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[seppuku]

Re: Panasonic 42' Plasma TC-P42x3

I'm not clear on what you want a pic of. Included is a pic of the labels on the psu side and the connector on the video input board.

[tom66]

Re: Panasonic 42' Plasma TC-P42x3

That is the picture I required.

Do you have a digital multimeter/voltmeter available?

Set your meter to DC volts, if it is manually ranging use the 20V scale. Red probe in volts/ohms, black in COM.

Connect the black probe of the meter to the chassis of the TV (wall bracket, back of display panel, etc.)

Touch the red probe on the pin corresponding to STBY5V. The connector must be inserted. A small metal crimp is exposed where the wire goes into meet this connector, you will be probing this point.

What voltage do you measure?

[seppuku]

Re: Panasonic 42' Plasma TC-P42x3

I'm assuming this must be plugged in for this measurement. I'm hesitant to plug it in with the back exposed since I have limited knowledge working on an exposed circuit. Unplugged this reads 0 volts. If it must be plugged in, any basic safety tips on not shocking myself?

[seppuku]

Re: Panasonic 42' Plasma TC-P42x3

Forgive my ignorance in advance.

[tom66]

Re: Panasonic 42' Plasma TC-P42x3

I'm assuming this must be plugged in for this measurement. I'm hesitant to plug it in with the back exposed since I have limited knowledge working on an exposed circuit. Unplugged this reads 0 volts. If it must be plugged in, any basic safety tips on not shocking myself?

Yes, sorry, it must be plugged in.

Safety tips.
- Do not touch any exposed metal parts on the power board or other parts in the set, with the exception of the metal chassis and HDMI input board, which are considered low voltage safe.
- If in doubt/needing clarification always ask.
- Have someone watching you and present in the room if you are inexperienced. They can call for help if necessary.

Working on mains powered devices always poses a danger. I have been shocked once before, but never by a plugged in device. (Capacitor discharge.) If in doubt, consult someone with more experience...

[seppuku]

Re: Panasonic 42' Plasma TC-P42x3

DC voltage reads .010 volts.

[tom66]

Re: Panasonic 42' Plasma TC-P42x3

Ok, now please measure S1 and S0.

[seppuku]

Re: Panasonic 42' Plasma TC-P42x3

.012 volts each

[tom66]

Re: Panasonic 42' Plasma TC-P42x3

This points to a defective power board. But first, to confirm your meter is working could you please test a fresh 1.5V or 9V battery and see what your meter measures... just to make sure it is working right.

[seppuku]

Re: Panasonic 42' Plasma TC-P42x3

Haha, well this is embarrasing. I didn't notice that my multimeter auto reset to ac voltage....

So S1 and S0 read 1.1 millivolts and stby5v reads 5 volts.

[tom66]

Re: Panasonic 42' Plasma TC-P42x3

Ok, if you press the power button on the side or front of the TV, do S0/S1 change?

[seppuku]

Re: Panasonic 42' Plasma TC-P42x3

no they don't

[tom66]

Re: Panasonic 42' Plasma TC-P42x3

That is odd. I'm going to need to consult the service manual.

[tom66]

Re: Panasonic 42' Plasma TC-P42x3

Ok, my guess would be the A board is bad... as you have 5V standby. Maybe wait for tw2005 to chime in, he may have additional info.

[seppuku]

Re: Panasonic 42' Plasma TC-P42x3

Thanks for the help so far. Hopefully I can narrow it down because parts for this thing or non-existant.

[tw2005]

Re: Panasonic 42' Plasma TC-P42x3

I was looking at the ST30 flowchart for this, may be able to use that for fault finding.

You have relay click and standby at plugin so next step it says

Unplug the TV. Place your volt-meter on pin 1 of connector P6. Plug in the TV and press the power switch

Is there 3.2V present when the power button is pressed?

[tom66]

Re: Panasonic 42' Plasma TC-P42x3

Just to be clear tw, there are two power switches on this set I believe? the S0/S1 one interrupts all power including standby ("fake power off" mode), then there is a normal standby on/off one.

[tw2005]

Re: Panasonic 42' Plasma TC-P42x3

I'll check, it looked like a soft start. The link at P34 I believe is in place instaed of a traditional main on/off switch, then momentary push switch to start the TV, S0,S1 appear to be signals from IC9300