Panasonic TC-L32C22 Won't Turn On

[neilc6]

TV doesn't have standby LED but has standby voltage and does attempt to turn on when the power button is pressed. It shuts down in a second possibly detecting an error. TV does have diagnostic blinks but since the front LED is off, I'm not sure if it is blinking. If I had a scope, I could probe that line.

Service manual and schematic can be found online.

When on, PFC circuit which powers (12V, 17V, 32V) gets around 390V before shutting down

connector pins off/on
ADIM
INV-PWM
INV_ON 0V/0.05V
INV_SOS 3.3V/3.3V
RELAY 0/6V
TV MAIN_ON 0V/.005V
TV SUB_ON 0V/2.3V
17V 0V/18V
DTV12V 0V/5-6V
TUNER6V 6V/6V
5VS 6V/6V

Measured with the ccfl connectors off but same behavior when connected. 12V, 17V and 32V lines aren't shorted.

[budm]

Re: Panasonic TC-L32C22 Won't Turn On

TV SUB_ON 0V/2.3V
So the SUB_ON control signal goes to 2.3V for seconds and then drops back down to 0V?
You do not need the scope, all you have to do is to check the Voltage at both legs of the power LED against GND when power switch is toggled, see page 35.
There are also many Voltages on the main board that you need to check, look at page 31, you can see what the STBY5V is connected to to provide STB3.3, STB1.2, once the power supply board gets the TV_SUN_ON to turn on the reset of the power supply, the STBY5V is taken over by the SUB5V which is generated by the IC5608 which is fed by the DTV12V, that DTV12V is used to generate many Voltages that you test when the power comes on for seconds before dropping out.
Page 31 and 32 are great guide showing how the powers are distributed.

[neilc6]

Re: Panasonic TC-L32C22 Won't Turn On

TV_SUB_ON drops to 0V when it shuts down. I remeasured DTV12V with a non-autoranging meter to get a quicker reading and it is only reaching 5-8V. I suspect this is the main problem since this voltage is used on the main board and regulated down to lower voltages which also trigger error detect signals (low/no voltage). Checked the cap on the 12V output line C7508 and it tested good. Also reheated the transformer pins. The other outputs from the transformer (17V and 32V) look ok.

Also checked OVP circuit (R7750/J13) on PS board and it doesn't go high.

Tried a 10K pullup on the TV_SUB_ON line to 5VSB with connector off and power supply didn't turn on. May need a load or some other signal.

The connector to the IR/front LED board is broken which is why I'm not getting a front LED. Will have to wire the 3 signals I need (R_LED,3.3V standby, and GND) directly. G_LED is not populated and no wire.

[neilc6]

Re: Panasonic TC-L32C22 Won't Turn On

Got the power supply to turn on without the main board connected. I was missing the 6V on the RELAY pin. With PS forced on, PFC voltage peaks around 416V on before settling at 390V. When monitoring the 12V and 32V outputs, they peak up and then slowly drop even with no load and the PFC steady. This leads me to suspect IC7301 (SSC9512) is shutting down.

[neilc6]

Re: Panasonic TC-L32C22 Won't Turn On

I searched SSC9512 and found this post.

https://www.badcaps.net/forum/showthread.php?t=30457

Check R7303, R7305 and R7306 by lifting one leg up and R7306 measured a bit high. 1.3M instead of 1M. Replaced it and TV powers up!!!

Power supply board number is TNPA5123CA.

[budm]

Re: Panasonic TC-L32C22 Won't Turn On

Great job, those resistors with high resistance tend to drift off in value a lot.