Samsung UE46D8000 Power Supply BN44-00427A voltage fluctuating.

[lin4sm]

There is Samsung UE46D8000 that was working perfectly. Now voltages on power supply BN44-00427A is fluctuating.

As far as I know outputs from power supply should not fluctuate. I can hear quiet noise from part. It is like clock ticking every 2 - 3 sec. Whenever it is connected to main board relay is clicking.

This is what I am getting whenever I am measuring voltages on output to main board:

1. 0D_Level 0.7-5.2 V
3. 0D_ON/OFF 0.7-5.0 V
5. GND 0V
7. B13V 0.7-2.6V
9. B13V 0.7-2.6V
11. Vamp 0.7-2.6V
13. Vamp 0.7-2.6V
17. B5V 0.6-5.3V
19. B5V 0.6-5.3V

2. P_DIM4 0.1-3.8V
4. P_DIM3 0.3-3.4V
6. P_DIM2 0.1-4V
8. P_DIM1 0.3-3.9V
10. B13V 0.6-2.6V
12. BLU on/off 0.6-4.6V
14. GND 0V
16. GND 0V
18. A5V 5.363V
20. Power ON/OFF 3.355V

All ground shows 0V, 18 and 20 pins are stable. Other fluctuating.

Checked back of the board, but do not see any cracked solder joints, done quick test on diodes and transistors, looks OK.

Whenever checking voltages I can see fluctuation on both AC and DC sides.

First I was thinking of bad LEDs, but whenever I have taken backlight out all LEDs lights up with multimeter on diode mode. Looks like no shorts between all lines of LED backlight.

Any suggestions?

Image of the power supply taken from google.

[Ashry]

I have the same thing fluctuate ac and DC but stand by voltage is stable
This case after dead 12v and led voltage
I disconnect the over current protection from ic 25600 so the standby voltage ok but fluctuation problem.

Did you solve the problem ?

[lin4sm]

It was very long time ago. Most likely I have bought 2nd hand part for this TV.

[nomoresonys]

I have the same thing fluctuate ac and DC but stand by voltage is stable
This case after dead 12v and led voltage
I disconnect the over current protection from ic 25600 so the standby voltage ok but fluctuation problem.

Did you solve the problem ?

maybe check out those 5 diodes on the heatsink and CM866, CM878.