Zenith Z42PJ240 no power

[freelancenoob]

Tv was a dumpster find. Powered on and worked. Took home and it powered on again. Now it gets no power at all. No stand by light. I don't like the power button as its touch sensitive (no actual button). Is there a way to bypass the switch to turn the unit on?

Anyway I checked all the fuses and all are good.

Where do I go from here?

[dskall]

Re: Zenith Z42PJ240 no power

Need voltages from connector that goes from power supply board to main board. Will need pin#- PIN DESCRIPTION -Pin voltage in standby-Pin voltage when pushing power button and picture of connector on power supply board.
Format:
Pin# - Pin Description - Pin Voltage standby - Pin voltage power on
1 - XXXXXXX - XXv - XXXv
2 - XXXXXXX - XXXv - XXXv
3 - XXXXXXX - XXXv - XXXv
4 - etc.

[freelancenoob]

Re: Zenith Z42PJ240 no power

Ok this is odd. Before I plugged in the unit I decided to just double check all grounding screws and make sure they were tight. After that was done I plugged in the tv. Power supply board made a click noise like a relay tripped. Standby light came on and I was able to turn the tv on. Turned it off and on a couple times no problem. I then pulled the power plug. Once I plugged it back in the tv was dead again. No click noise from the psu.

In standby i got 3.5v from the standby pin. nothing from anything else on that header. After turning on the tv I got 17v from the 17v pin and i got 5v from the 5v pin and standby went to 5.2v. After unplugging the tv and plugging it back in I get nothing on standby. I do have 119v going to the input plug on the board though.

[CapLeaker]

Re: Zenith Z42PJ240 no power

When the TV doesn't want to turn on, check the STBY voltage that goes to the main board. Also check for cold solder joints. I would investigate the STBY voltage circuit. Maybe there is a bad cap or a crack or something...
You also can try heating the board with a hair dryer, etc.

[freelancenoob]

Re: Zenith Z42PJ240 no power

When the tv doesn't have a standby light and it will not turn on I checked and I get no voltage.

[dskall]

Re: Zenith Z42PJ240 no power

Maybe push around on board with nonconductive tool while plugged in and see if anything changes

[freelancenoob]

Re: Zenith Z42PJ240 no power

Poked and prodded around the board and no change. I did however unplug the main board from the ps board and i could get the relays to click again like it was turning on the tv. Unplug the tv and nothing. So I plug back in the mainboard and as soon as i plug in the mainboard with the power unhooked the relay clicks again.

[CapLeaker]

Re: Zenith Z42PJ240 no power

so is stby voltage there on the PSU with the main board disconnected?

[freelancenoob]

Re: Zenith Z42PJ240 no power

correct

[freelancenoob]

Re: Zenith Z42PJ240 no power

I grabbed a manual from this site


Below is the method it shows for testing power on failure.