On Friday, February 19, 2021 at 7:42:14 AM UTC-5, wrote:
On Friday, February 19, 2021 at 1:09:20 AM UTC-5, wrote:
On Thursday, February 18, 2021 at 7:04:27 PM UTC-5, wrote:
On Thursday, February 18, 2021 at 5:39:46 PM UTC-5, wrote:
On Thursday, February 18, 2021 at 12:02:55 PM UTC-5, wrote:
On Wednesday, February 17, 2021 at 3:59:00 PM UTC-5, wrote:
Hi Group, can someone help please, im working on a Samsung un55ku650dfxzaTV, that has no pic, no power standby light blinking. when testing the PS board on pins 3,5,7,9,.. i get 14v to 8v fluctuating, legend says they're supposed to 13v on all 4,.. im assuming leaky cap.. the filter caps read 395v on both,.. any help will be taken seriously,
Disconnect the power cable between the main board and the power supply. With the main disconnected, the power supply and go into free-run when AC is applied. All marked voltages should appear and the backlights should turn on. If the back lights turn on, your LEDs are OK and it's likely a bad main, but there could still be a problem on the power supply. If the back lights don't turn on and you get 300V across the 450V electrolytics near the LED connector, you've got an open LED inside the display.
I Disconnect the power cable between the main board and the power supply, no backlights, still erratic voltages on pins 3,5,7,9.. and also erratic on the caps near the led connector, no where near the voltage you said, more like 106v down to 90v..
Disconnect the LEDs from the power supply and leave the main disconnected, plug in the AC. If the voltages return, an LED burned through and shorted to the metal backed LED strip which is now shorted to the backside of the display "chassis". You can try reconnecting the LED harness and physically float the power supply board off the back pan (you want to isolate it from cold ground) by putting it in a shallow cardboard box or put a heavy blanket between the board and the chassis. The LEDs might light, but if they do, there will be a 300V potential between the now floating ground connections of the power supply and the cold chassis ground, so be careful not to get whacked. If it works, do not be tempted to permanently float the power board off the chassis because reconnecting to the main will ground it again....

If the voltages still stay down after disconnecting the LEDs and the main, replace the supply.
yep, voltages remained the same. still erratic.. replacing the PS.. Thanks for your help..
I think I have a KU power supply in stock. Let me free run it and check those voltages before you buy a board. Samsung does some weird things on certain models. I'll post later today when I get to work.

OK,..