Sony KDL-32EX720 power supply doesn't turn off right away

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Hi all,

I have a Sony KDL-32EX720 (June 2011 model) that I received from someone who said it didn't work. I plugged it in and it seems to be working fine. However, I noticed that the power supply 12v rail doesn't switch off right away--it takes 35 seconds from the time you switch it off (the power_on signal transitions from 3.2v to 0v right away) for the 12v rail to switch off (the voltage doesn't gradually decrease--it seems to cleanly switch to 0v at around the 35 sec. point). I also hear some whistling sounds (possibly from a transformer) during this 35 second time period.

Maybe this is normal for this power supply, but seems rather strange. Thanks for any help.

[anmol]

Re: Sony KDL-32EX720 power supply doesn't turn off right away

Resolder T6501- D-6601/4, replace C 6603-4-5-6.

Refix CN 6150 cable both end.

Wbr

[crosstalk]

Re: Sony KDL-32EX720 power supply doesn't turn off right away

Thank you for the help. It turns out I was wrong about the power_on signal from the main board--I was measuring the wrong pin on the connector. The main board is not deasserting the power_on signal. I tested the power supply by jumpering standby and power_on and the power supply seems to turn on and off correctly.

Any thoughts on how to repair this problem? I ran the software update on the main board, but that didn't change anything. The ac_off_det signal is 3.3v when the power supply is in standby, so I was thinking that voltage might be leaking on to the power_on signal on the main board. Both signals go through a 100 ohm resistor network, but I can't find any problems with that component. I must be missing something here.

[crosstalk]

Re: Sony KDL-32EX720 power supply doesn't turn off right away

Is it possible this delayed power off is normal for this set? I have the "update software while in standby" option off. I am confused because I received this for free from someone who said it doesn't work, but I can't find anything wrong except this power off thing.