Samsung UN32N5300 SmarTV -2018

[jason123]

Hi Folks,
Got this TV, with power / main combo board. The TV has the front LED indicator on. Indicator Seems responsive to remote and push button activity.

No Backlight or image with flashlight at all. Optical Audio doesn't come on. First check was backlight. Checks out with tester, but still i opened it up and each LED checks out. 3 strips, 6 LEDs each.

Second check the large cap. It never goes into full voltage (running at 160 VDC), but PFC doesn't seem to kick in. when I press power button, momentarily goes to 163, then back to 160. Any suggestion where to look?

Thanks

[neilc6]

Very difficult to debug these combo boards. If TV doesn't turn on, likely issues with the processor or eeprom. I had one with a blown fuse and shorted FET. Replaced both and shorted again. Would just replace the whole board.

[dskall]

Check voltages on main. I think optical is on 3.3v

[jason123]

3.3 v, 5 v, 12v, 1.9 v are all present. Led voltage is about 27 V differential (not enough to turn leds on- need 54 v or so)

[dskall]

Well worst case if rest is working is buy an inverter for your backlights.

[dick_barton]

Just a quick thought. Can you check the resistance and inductance of T9101C. There have been a few issues with inductors running hot and failing in the led circuits.

[dskall]

Maybe someone smarter than me will jump in. Not sure if there is pfc on this board. Is that one coil for pfc or just filtering?

[dick_barton]

Another though is...........have you measured the voltages at the led connector (with leds disconnected) and then power up and see what the voltage peaks to. If ithe peak exceeds the 57V then it's possibly faulty led(s).

[jason123]

Originally Posted by dick_barton

Just a quick thought. Can you check the resistance and inductance of T9101C. There have been a few issues with inductors running hot and failing in the led circuits.

R = 1.8 Ohm
L= 1.216 mH

[jason123]

Originally Posted by dick_barton

Another though is...........have you measured the voltages at the led connector (with leds disconnected) and then power up and see what the voltage peaks to. If ithe peak exceeds the 57V then it's possibly faulty led(s).

÷ LEAD READS 110V NEGATIVE LEAD READS 77 V. So Differential is less than 57 v

[jason123]

Originally Posted by dskall

Well worst case if rest is working is buy an inverter for your backlights.

No image is displayed on screen , so not just no backlight, unfortunately

[dskall]

Is your processor getting warm? Oscillator working, voltage to eeprom? Thinking you should have a 1.2v to run processor.

[jason123]

Originally Posted by dskall

Is your processor getting warm? Oscillator working, voltage to eeprom? Thinking you should have a 1.2v to run processor.

processor is getting warm, crystal has some activities (loading of a scope pretty much messes it up), and eeprom has 3.3 V. I don't see 1.2 V on the board, but I do see 0.9 (core?), 1.9, 3.3,...

[dskall]

Getting voltage to t-con? Data going out on lvds? Voltages on t-con?

[jason123]

Originally Posted by dskall

Getting voltage to t-con? Data going out on lvds? Voltages on t-con?

Getting voltage to TCON - 12V on both sides of the fuse. 3.2V is on TCON also. Initial activity on the LVDS but then nothing

[dskall]

And the other t-con voltages?

[dskall]

You might want to read some part# off of 8 pin chips around your processor. Maybe multi voltage regulator chips.

[jason123]

The only thing that I could find suspicious about the board, is this 630V Cap that is swollen and the epoxy cracked as shown in photos. It's not shorted, and it has about 2.2 nF measured capacitance. Any idea where I can get a replacement if you think it might be the culprit?

I do have a board installed in the TV and it's fine.. Would be nice to fix this one.
Thanks

[R_J]

The cap is usually used to connect the transformer winding to ground. digikey should have them

[dskall]

Funny it didn't look bulged in first pictures. Now you have a board that you could compare voltages on. Suspect maybe bad processor or firmware.