Samsung UE65h5400AW Won't Turn On (Has Red Standby Light)

[DutchDIY]

Hey everyone!

I have a Samsung UE65H6400AW tv here that won't turn on.
What I have tested/checked so far;

• no visible burnt or blown caps or other components
• power board seems in working order, voltages are oke, fuse is fine, with cable to main disconnected the LED's come on and stay on
• have done various variations of resets by holding down the power button

Edit: remote is ruled out.

I am hoping that some of you can tell me what to check/test next. I am no stranger to soldering, and am totally committed to learning.

Thanks for reading!

[dskall]

Re: Samsung UE65h5400AW Won't Turn On (Has Red Standby Light)

Need to check your voltages to mainboard in standby, and after you press power button.

[DutchDIY]

Re: Samsung UE65h5400AW Won't Turn On (Has Red Standby Light)

Need to check your voltages to mainboard in standby, and after you press power button.

According to the imprint on the power supply board, pins 5,7,9,11 & 13 should have 13V.
Upon plugging in the power coard, I measure 12.88V on all of these pins, but they drop to just over 9V about every 2 seconds before going back to 12.88V.
After pressing the power button, there is no change in this.

[DutchDIY]

Re: Samsung UE65h5400AW Won't Turn On (Has Red Standby Light)

Anything else I can check?

Edit:
Maybe some useful info, upon pressing the power button a faint click can be heard soon after, coming from the main board.

[DutchDIY]

Re: Samsung UE65h5400AW Won't Turn On (Has Red Standby Light)

Should I buy another main board?

[nomoresonys]

Re: Samsung UE65h5400AW Won't Turn On (Has Red Standby Light)

good possibility its the mainboard, when you get backlight on with that cable removed it usually means the backlight circuit and powerboard are ok. can you post a good clear picture of the connector on powerboard with the legend of the expected voltages? or just report the voltages you have in standby(tv plugged in) and when you power on the tv, report both conditions, as in: pin number, expected voltage and your actual voltage, example pin 1 ps-on, off 0volts, on 3.5volts.

[DutchDIY]

Re: Samsung UE65h5400AW Won't Turn On (Has Red Standby Light)

Thanks, will see if I can get one!

[DutchDIY]

Re: Samsung UE65h5400AW Won't Turn On (Has Red Standby Light)

good possibility its the mainboard, when you get backlight on with that cable removed it usually means the backlight circuit and powerboard are ok. can you post a good clear picture of the connector on powerboard with the legend of the expected voltages? or just report the voltages you have in standby(tv plugged in) and when you power on the tv, report both conditions, as in: pin number, expected voltage and your actual voltage, example pin 1 ps-on, off 0volts, on 3.5volts.

The legend says 13V for 6 of the 18 pins, and I measure 12.88V on all, with it every few seconds dropping to just over 9V. I will post a pic soon.

[nomoresonys]

Re: Samsung UE65h5400AW Won't Turn On (Has Red Standby Light)

to repeat: " just report the voltages you have in standby(tv plugged in) and when you power on the tv, report both conditions, as in: pin number, expected voltage and your actual voltage FOR ALL pins, example pin 1 ps-on, off 0volts, on 3.5volts." I would never on purpose ask you to do anything unnecessary.

[Storyteller12]

Re: Samsung UE65h5400AW Won't Turn On (Has Red Standby Light)

Can you post good pics of your mainboard

[DutchDIY]

Re: Samsung UE65h5400AW Won't Turn On (Has Red Standby Light)

Here are some pictures, are they good?

[DutchDIY]

Re: Samsung UE65h5400AW Won't Turn On (Has Red Standby Light)

to repeat: " just report the voltages you have in standby(tv plugged in) and when you power on the tv, report both conditions, as in: pin number, expected voltage and your actual voltage FOR ALL pins, example pin 1 ps-on, off 0volts, on 3.5volts." I would never on purpose ask you to do anything unnecessary.

Standby;
Pin 1: 0V
Pin 2: 0V
Pin 3: 0V
Pin 4: 0V
Pin 5: 12.88V (expected 13V)
Pin 6: 0V
Pin 7: 12.88V (expected 13V)
Pin 8: 0V
Pin 9: 12.88V (expected 13V)
Pin 10: 0V
Pin 11: 12.88V (expected 13V)
Pin 12: 0.188V (idk what to expect? Legend says PS_ON)
Pin 13: 12.88V (expected 13V
Pin 14: 0V
Pin 15: 0V
Pin 16: 0V
Pin 17: 0V
Pin 18: 0V

Next I will post the voltage after pressing On button.
About the above voltages, those drop every second to just over 9V (and pin 12 drops slightly as well), and it coincides with the ticking of what I believe are the mosfets.

[DutchDIY]

Re: Samsung UE65h5400AW Won't Turn On (Has Red Standby Light)

The readings are the same after pressing the power button.. but I used to see the standby LED react to me pressing the power button, don't see that happen anymore..

[lotas]

Re: Samsung UE65h5400AW Won't Turn On (Has Red Standby Light)

Check the voltages on the converters on the motherboard.

[DutchDIY]

Re: Samsung UE65h5400AW Won't Turn On (Has Red Standby Light)

Check the voltages on the converters on the motherboard.

Will check that, thanks, which pins of those chips should I check?

[lotas]

Re: Samsung UE65h5400AW Won't Turn On (Has Red Standby Light)

Usually the output voltage is on the inductor.

[DutchDIY]

Re: Samsung UE65h5400AW Won't Turn On (Has Red Standby Light)

Usually the output voltage is on the inductor.

I'm sorry I don't know which of those feet to probe with the multimeter.
I added a closeup of one of the 8 legged chips.

[Storyteller12]

Re: Samsung UE65h5400AW Won't Turn On (Has Red Standby Light)

Start checking the smd capacitors and diodes on the main board. Where ever you see an 8 pin ic I would probe around there first. If I’m not mistaken I fixed this board before and it was a bad diode

[DutchDIY]

Re: Samsung UE65h5400AW Won't Turn On (Has Red Standby Light)

I am finding a bunch of smd's beeping on both ends (with one probe to GND). That must not be good?

[lotas]

Re: Samsung UE65h5400AW Won't Turn On (Has Red Standby Light)

I'm sorry I don't know which of those feet to probe with the multimeter.
I added a closeup of one of the 8 legged chips.

See datasheet.