Samsung LE40R74BD Clicking Relay (VIDEO INCLUDED)

[jamiem1987]

Hi guys, I've got a Samsung LE40R74BD in for repair, the fault is the relay clicking and the set is not powering up.

Heres a youtube video showing the fault..  http://www.youtube.com/watch?v=4mx7WJqq1wk

I've checked all the capacitors and changed the ones that read low as this usually causes this fault but this hasnt sorted it.

I've got another signals and digital pcb board from another set I've swapped over to rule these out, also tried powering up with the inverters disconnected as I thought this might be holding it off but it seems not.

Basically i've narrowed it down the psu board, which is BN44-00134A, aside from the caps which I've changed I'm not familiar with any other faults with this set,

Anyone any ideas?

[tom66]

Did you reset the EEPROM on your original main board (maybe the other board you have has a corrupt EEPROM too.)

Check the PSON voltage is there and all rails are coming up properly. Check the PFC diode is not leaky; check the bulk cap has around 400V; check for cold joints and if possible, check the rails with a scope.

[jamiem1987]

Thanks for the prompt response, I've stuck the signals board in a 32" set and it powers up ok so I'm confident its not the EEPROM, will check the diodes and joints,

many thanks!

[tom66]

Unplug T-con does set power up? Could be a shorted MLCC.

[jamiem1987]

There's definitely no dry joints and unplugging the TCON results with the same fault, there's no noise on any of the rails and none of them come up to proper voltage, the cap has 400v on pretty continous. The PSON voltage comes up and goes down in time with the relay clicking,

At a total loss with this one! Everything measures okay

[sparky]

hi
looks like eeprom never had one from a 40" motherboard  work in a 32"
dave

[tom66]

If PSON is going up and down the main board is faulty. As Dave says, maybe they are not compatible? (Different connector pin out, different output voltages etc.)