Samsung UN55JS8590 clicking issue on and off

[paddz123]

Hello,
my Samsung LED TV stopped working, when i try to turn it on the relais just clicks on and off and after about 15 seconds clicks on and off again and again. I read about bulged capacitors on the power supply board but mine looked fine. Standby voltages on the power board were at 9V which was written on the board so that is fine.

When i unplugged the T-con and mainboard and connected the tv to power the backlight came on. When i did this with a connected t-con but disconnected mainboard there was just one click and nothing else happened, when I then reconnected the mainboard the clicking on and off started again. So I think it is a mainboard Issue.

My manboard numer is BN94-07833B (BN41-2356B) and i can not find any plans for that. I read about the hdmi switching IC going bad on some other mainboards, but there were no shorts that i could measure on the IC. I tried a EEPROM reset but nothing happened when i connected the SDA pin to VCC.

Does anyone have a clue where i could start? Is there any common issue? Or at least some kind of service manual for the tv?

thank you

 

[zzyzx]

If it fails to start like you described think power supply. Replace the big electrolytics in the power supply. It needs them to start up, oversize is ok in this case.

 

[MTJB]

Yes, be sure to check all the larger E. Caps in the SMPS. Also be sure to check them for leakage. Also check for bad solder joints on any of the power semiconductors on the power board. I have seen a lot of Samsung models that seem to have a 3 leg 15v regulator IC, that is turned on by the CPU chip, that comes unsoldered from overheating, because it is free standing and not mounted to a heat sink. The PCB traces may also need repairing at this device. You may be able to order a schematic from Samsung, but my experience is; it most likely won't include the power board!

 

[unclejed613]

samsung doesn't publish schematics of their main boards (from what you describe it does sound like a main board issue) the supply is shutting down from overcurrent. however if you still think it's the power supply... monitor the "power good" pin coming back from the main board with a meter and see if it changes state when you try to power on the TV. if it doesn't change state, then just monitor all of the power outputs to see which one isn't coming up. or carefully remove the power good wire from the header of the cable from the PSU to the main board and turn the TV on, then check all of the power supply outputs