Samsung UN60D6000 LED Backlight flashing

[ljintexas]

Re: Samsung UN60D6000 LED Backlight flashing

When I unplug the main board cable and apply AC power to the SMPS, I have one click, and 211 volts DC to each of the LED arrays. The board says it should be 333 volts DC. If I leave it plugged in for say an hour, the two large transformers with the silver heatsinks in the center of the board get what I would term Hot.

Thanks to All

LJ

[ljintexas]

Re: Samsung UN60D6000 LED Backlight flashing

Is it safe to say that thus far, the smps has issues as it does not fire the LEDs with the Main Board cable disconnected and AC supplied to the board??

Thanks

LJ

[budm]

Re: Samsung UN60D6000 LED Backlight flashing

I would like to verify the DCV between the two legs of the main filter cap CP804 in the primary side, then the DCV between the two legs of the caps CM851, 852 LED driver power supply in the cold side, this done with just the power supply board by itself.
The next test you need to leave the two probes of the meter on cap C9155 legs then apply the power to the board to see how high the Voltage goes up to and then wait a few seconds to see how low the Voltage drops down too, then do the same again on cap C9255.

[ljintexas]

Re: Samsung UN60D6000 LED Backlight flashing

Thank you Bud. I will perform the tests and post back the results this evening. To clarify, should the LED feeds be plugged into the PS board or unplugged when performing these tests?

I appreciate your help very much.

LJ

[ljintexas]

Re: Samsung UN60D6000 LED Backlight flashing

I see where you say to do the tests with just the PS board by itself..sorry for the stupid question!

[budm]

Re: Samsung UN60D6000 LED Backlight flashing

Thank you Bud. I will perform the tests and post back the results this evening. To clarify, should the LED feeds be plugged into the PS board or unplugged when performing these tests?

I appreciate your help very much.

LJ

Try both.
Opps, I have your board mixed up with another OP so disregard as to what I said about the 25V and the tabs.

[budm]

Re: Samsung UN60D6000 LED Backlight flashing

BTW, I need good clear straight shot pictures of the bottom side of the power supply board, shopjimmy does not have the pictures I need to trace out the board.

[ljintexas]

Re: Samsung UN60D6000 LED Backlight flashing

Thanks Bud... I will try both

I am charging up my 16 mp camera for a shot of the bottom of the board.

Will post tonight.

Thank You Sir

[ljintexas]

Re: Samsung UN60D6000 LED Backlight flashing

There is no difference in the readings whether the LED harnesses are plugged in or not:
CP804 390.6 Volts DC leg to leg
CM851 217 Volts DC
CM852 217 Volts DC

Both C9155 and C9255 measured 216.7 Volts DC very stable..no drop off

Thanks

[budm]

Re: Samsung UN60D6000 LED Backlight flashing

OK, so the PS-ON is OK because you do have the 390VDC on the main cap.
In the LED driver power supply, the input Voltage to the LED boost converter circuit is 217V (CM851), the output of the Boost converter is also 217V (C9155) so the Boost converter is not working.
So we need to verify for sure if you do have BL-ON (BLU-ON) signal at the power supply board connector or not.
BTW, did you leave the probes on this cap when you power up the board? I want to make sure IF you see the Voltage jumps up above 217vdc or not.
If the BL-ON is present and you did not see the Voltage on cap C9155/9255 jumps up above 217V then for sure the Booster circuit is not active and we need to find out why.

[ljintexas]

Re: Samsung UN60D6000 LED Backlight flashing

I did leave the probes on and it did not jump up above 217 volts.

[budm]

Re: Samsung UN60D6000 LED Backlight flashing

OK, I will wait to see the pictures of the bottom side of the board to locate the LED driver/controller IC.

[ljintexas]

Re: Samsung UN60D6000 LED Backlight flashing

I will verify BLU_ON at connector with main board disconnected.. I did see 5.3 volts on that pin when main board was connected.

[budm]

Re: Samsung UN60D6000 LED Backlight flashing

I will verify BLU_ON at connector with main board disconnected.. I did see 5.3 volts on that pin when main board was connected.

If you did have DCV of >2.5V on the BL-ON, then more likely something in the LED driver circuit is the problem.

[ljintexas]

Re: Samsung UN60D6000 LED Backlight flashing

Here is back side of board

[ljintexas]

Re: Samsung UN60D6000 LED Backlight flashing

Would that be the 16 leg IC on center right side of board?

[budm]

Re: Samsung UN60D6000 LED Backlight flashing

https://www.badcaps.net/forum/attach...8&d=1465875250
Bottom left, 20-pin SMD in the section where the two LED connectors are.

[ljintexas]

Re: Samsung UN60D6000 LED Backlight flashing

Slc4011m
bt9l 13gu

[ljintexas]

Re: Samsung UN60D6000 LED Backlight flashing

Thanks Bud for helping me find the source of the problem!

[ljintexas]

Re: Samsung UN60D6000 LED Backlight flashing

I can only find this IC from China.. Aaaargh!