Sony KDL40EX501, won't power on, no standby light

[macinjosh]

Hello all,

My Sony Bravia recently (after a storm) shows no red standby light at all. Taking it apart, I noticed that one of the ICs on the main board seemed to have a hole in it, so I replaced the main board.

However, I still have the same problem.

I've looked at the SONY technical flowchart for these models, but am stuck at what to do at this point. Here's what I've done:

1. I've verified that the power supply board is getting 120v AC.

2. Verified standby voltage, about 3V DC on pin 1 of the power supply.

3. Verified about 3V DC on pin 2 (AC_DET_OFF, I think?).

Here's where I lose clarity. Should I measure pin 3 of the power supply with the connector (to the main board) and its wires attached, or not?

If I measure it with the connector off, I get 0V on pin 3. If I measure it with the connector and wires attached, I briefly get about 3V, but only for about four seconds, after which it goes to 0V. The whole time, I did not push the Power button at all.

What should I look for next? Is it certain that the power supply board is bad?

Thanks!

Josh

[lotas]

Re: Sony KDL40EX501, won't power on, no standby light

Power Supply Sony AZ1-L G2HE

[macinjosh]

Re: Sony KDL40EX501, won't power on, no standby light

Thank you, but I'm afraid the diagram by itself doesn't help me much. Can someone explain to me what to make of the situation I described, and what to do next?

[dick_barton]

Re: Sony KDL40EX501, won't power on, no standby light

You could disconnect the power supply from the mainboard ( power to the set off) and connect a 1K ohm resistor between the STBY3.3V (Pin 1) and Power On (pin 3) and then power up the TV and check if the 12V and 24V supplies are present and correct.