Phillips 32PFL4507/F7B humming sound, no power

[jackal68]

Hi

Im trying to fix this Phillips 32" led tv, 32PFL4507/F7B. There is a humming sound when the power plug is connected. The humming goes away when I disconnect the cable from the powerboard to the mainboard. The humming seems to be around the mosfet/330uf capacitor area of the powerboard.

I have taken out the mosfet and tested it with a DMM and it seems to be fine. I also checked the voltages going to the mainboard and they're totally off. I'm not getting 3.3v standby (no light at the front), where it is supposed to be 24v, i'm getting 2.3v, and where it is supposed to be 21v, I'm getting 1.0v.

Any suggestions as to where I should check next would be much appreciated.

thanks

[dick_barton]

Re: Phillips 32PFL4507/F7B humming sound, no power

What dc voltage do you have when you measure between the two legs of the 330uF, 200V capacitor. It should be 169V

Have you checked the 5W 1R2 ohm resistor

[mcluvin]

Re: Phillips 32PFL4507/F7B humming sound, no power

I'm a newbie researching my own issue, but this might be helpful to you?? Your problem sounds similar.

https://www.youtube.com/watch?v=uAFCTZCb1BA&t=899s

[jackal68]

Re: Phillips 32PFL4507/F7B humming sound, no power

Thanks, that was a helpful video. I'm not sure if that's a good rule of thumb to use capacitors of the same size without knowing the value, but I did find one of similar size so I decided to try.

For those who are looking for a solution, BIG THANKS to CraigR on this post which pointed to the shorted capacitors on the mainboard (see below his post).

In my case, C3105 was the faulty capacitors whereas the other two were fine (I guess they're in paralllel. Once I replaced the faulty one, the tv is working again!

Again, big thanks to this awesome community!

https://www.badcaps.net/forum/showth...ight=32PFL4507