Proscan 50" PLDED5066A-E no backlights

[mnpdreed]

Re: Proscan 50" PLDED5066A-E no backlights

Ic1f

[budm]

Re: Proscan 50" PLDED5066A-E no backlights

I would get the P/N of that IC1F and then find the spec sheet so you can at least find out if it has DCV at the VCC pin of the IC.
The BL-ON signal should activate that IC so it drives the GATE Isolation transformer to dive those two power MOSFET for transformer for the LED power supply.
It is probably PWM IC.

[mnpdreed]

Re: Proscan 50" PLDED5066A-E no backlights

Where should I start trying to trace it out. Thank you for helping

[budm]

Re: Proscan 50" PLDED5066A-E no backlights

It is good. This is not going to be easy without the diagram at this point to find out how that power section works. IC1F SMD IC on the bottom side looks to be the one that does the job.

[mnpdreed]

Re: Proscan 50" PLDED5066A-E no backlights

C10f=mmkp82 223j63d.

[mnpdreed]

Re: Proscan 50" PLDED5066A-E no backlights

Out of curcuit read 22.31 nf

[budm]

Re: Proscan 50" PLDED5066A-E no backlights

I think the LED power supply is not being turned on.
Transformer T1F is the Gate drive isolation transformer that drives the Q1F, Q2F which I do not think it is driving right now.
You can also check the rectangular cap C10F (transformer coupling/DC blocking cap for T2F to see if its capacitance is correct.

[mnpdreed]

Re: Proscan 50" PLDED5066A-E no backlights

I don't know if this will help but I tried to trace out what I could. Does this seem correct

[mnpdreed]

Re: Proscan 50" PLDED5066A-E no backlights

.661 V between legs of c8f and the same .661 V of c9f

[budm]

Re: Proscan 50" PLDED5066A-E no backlights

OK, so we do have Voltage for the LED driver circuit, the MOSFET Q 1F, Q2F are for driving the power transformer T2F which is for providing the Voltage for the LED driver circuit.
What DCV do you have between the two legs of the brown cap C8F, and between the two legs of brown cap C9F?

[mnpdreed]

Re: Proscan 50" PLDED5066A-E no backlights

I'm sorry I guess I posted it incorrect it is 384 v. Sorry for confusing you.

[budm]

Re: Proscan 50" PLDED5066A-E no backlights

L2 is the PFC inductor, the PFC and L2 are OK otherwise you will not have the 384V DC on the cap.
https://www.badcaps.net/forum/attach...0&d=1448075181
In the picture you show 173VDC on C13, you had indicated you were using the negative leg of the as the GND ref for the meter in post 1., but now you have 384VDC.

[mnpdreed]

Re: Proscan 50" PLDED5066A-E no backlights

384.0 V. It appears I loose the voltage on L2

[budm]

Re: Proscan 50" PLDED5066A-E no backlights

So verify the DCV again by measuring between the two legs of the main filter cap when TV is powered on to see what you have.

[CapLeaker]

Re: Proscan 50" PLDED5066A-E no backlights

the 400V main filter cap (that looooong skinny cap). Just be careful not to short or touch anything on the primary.

[mnpdreed]

Re: Proscan 50" PLDED5066A-E no backlights

Any suggestions where or how to look for it?

[budm]

Re: Proscan 50" PLDED5066A-E no backlights

You do have PS-0N but you do not have PFC boosted Voltage to run the LED driver circuit, you must get the Boosted Voltage first.

[CapLeaker]

Re: Proscan 50" PLDED5066A-E no backlights

I don't know if you saw this pic of the voltage readings and don't know if this means anything but it has voltage going into L2 but nothing coming out

Take the transformer out and check it. Maybe it is open (thermal fuse inside the transformer)?

[mnpdreed]

Re: Proscan 50" PLDED5066A-E no backlights

Ic 1

[mnpdreed]

Re: Proscan 50" PLDED5066A-E no backlights

Pics