TH-42PD60U 10 blink code

[jkomorek]

I followed the troubleshooting chart found here for 10 blinks before presing the power button http://tsn.pstc.panasonic.com/PASS/o...ing_Charts.pdf and I made it to the final step in which I am supposed to look for 14v coming off of P10 connector.

I am actually getting 17v off of that connector. I used a schematic of the board found here http://www.toms-service-manuals.com/...&mfg=Panasonic and I traced the 17V back as far as D536 which I have highlighted in the attached jpg. There is a transformer just before the diodes, but I see any marked voltages before that so I'm not sure how to troubleshoot.

This is where I am getting stuck. When I plug in the TV I get 3 (sounds like 4 actually) quick successive clicks, which from other posts I have found here indicates that I am "not getting 14v" at P10, so I think that I should assume it is the PS. However, I am really not confident about this. Any advice?

[tom66]

Re: TH-42PD60U 10 blink code

I believe 10 blinks is 15V failure, which could be over-voltage. Causes can include bad feedback circuit, bad voltage references and bad capacitors, the latter being rare on Panasonic sets.

[jkomorek]

Re: TH-42PD60U 10 blink code

Thanks, Tom. Any suggestions on how to continue my troubleshooting to find the damaged components?

[tom66]

Re: TH-42PD60U 10 blink code

Try to attach a 15 ohm, 20 watt resistor to the 15V line. If it stays as 17V, suspect feedback/reference, if it drops, suspect capacitor or other fault.

[jkomorek]

Re: TH-42PD60U 10 blink code

Ok, I just ordered the parts to test this with. Out of curiosity, how did you derive the resistor values and how will this tell me that the issue is reference as opposed to a PS fault?

[tom66]

Re: TH-42PD60U 10 blink code

17V / 15 ohms = approx 1 amp load
The 15V line on these is usually capable of around 3 to 4 amps.
Power dissipation determined by I^2 * R = 15 ohms * 1 amp = 15W. Select 20W to be safe.

Power supply feedback will act to keep the output at the setpoint, even if the setpoint is wrong. If this circuit is at fault, then the output will not significantly drop under load. If it does drop, it points to another fault in the power supply.