Ocosmo E32 no backlight

[caphair]

Tv powers up fine but no backlight.

Opened it up thinking it might be an led issue but noticed a diode measures shorted and a resistor looks blown (see picture)

Is there a way to determine if the LEDs shorted causing this without removing them from the panel?

Should I just replace the parts and see what happens?

If anyone has a schematic for this model that would help me trace back the circuit with the shorted diode

[caphair]

Re: Ocosmo E32 no backlight

I removed the diode and it was fine. I’m not sure if I’m just measuring across transformer legs in parallel.

The resistor that looks blown open is bad.

What should I check next

[budm]

Re: Ocosmo E32 no backlight

That 6.2 Ohm resistor is connected in parallel with that Diode that is why it shows conduction in both direction when you tested that diode still on the board.
What resistance do you get on each one of those two '3303' resistors?
What dc Voltage on each pin of the LED connector when you first turn on the TV?

[caphair]

Re: Ocosmo E32 no backlight

One resistor reads 300k and the other 5Mohm

I’ll do voltage tests tomorrow

What would that 6.2ohms resistor be used for? Current sensing?

[budm]

Re: Ocosmo E32 no backlight

One resistor reads 300k and the other 5Mohm

I’ll do voltage tests tomorrow

What would that 6.2ohms resistor be used for? Current sensing?

May be or may be not, you need to trace out the Cathode return pin of the LED connector to see if it is directly connected to one end of that resistor or not, another end of that resistor should be connected directly to GND.

[caphair]

Re: Ocosmo E32 no backlight

Ok I drew out the routing

The (yellow line) shows how the bad resistor is in series with the 330k next to it and the other end of the bad resistor connects to the ferrite bead? Which goes to the anode terminal of the led connector

Cathode side (orange line) of led connector connects to the 6.2ohm resistor

[caphair]

Re: Ocosmo E32 no backlight

Taking voltage measurements. When it’s in standby I get 35v on the red anode side of led connector.

When first power on voltage jumps to 124v then slowly decreases. Voltage at cathode of led connect remains at 0v the entire time

Does this indicate led failure?