rca rlded5078a-d

[smuddge]

rca rlded5078a-d

power comes on, no video at all.
everywhere i read it is the power supply that is causing the issue here.
I see shopjimmy has no power supplies.
I don't trust ebay and none are there either right now.

power supply model - ay128d-4sf11

no visible damage anywhere on the board.
this is the 3rd rca rlded5078a-d that i seen with the same problem.
this one was given to me so I would like to see if i can fix it.

[CapLeaker]

Re: rca rlded5078a-d

Does it have audio? How about video if you shine a flashlight into the screen? I wonder if the backlight come on and turns off again. You would have to upload some pics and do some measurements to find out

[smuddge]

Re: rca rlded5078a-d

No back light at all. doesn't flash on even for a second. Will check for audio but I don't think it has audio either. just powers on blue light on the front.
Tcon? mainboard? I will take whatever pics you want let me know.
no visable damage to any components.

[CapLeaker]

Re: rca rlded5078a-d

upload some pictures so we can see

[smuddge]

Re: rca rlded5078a-d

you want pictures of boards?

[CapLeaker]

Re: rca rlded5078a-d

Hi res pictures of the boards, yes.

[R_J]

Re: rca rlded5078a-d

Have you checked the voltage going to the backlight led's?

[smuddge]

Re: rca rlded5078a-d

here are the pics as requested.
I have not tested anything.
still learning so i am not sure what i should be looking at here.
tell me what and where to measure and i will see what i can find out.
appreciate this help.
you guys are all really helpful!!

[CapLeaker]

Re: rca rlded5078a-d

On the power supply I don't see a pinout. Is it maybe printed on the back of the board?
Can we see the whole back of the TV with all boards connected?

First off I'd be probing the voltage rails on the PSU to see if everything is there. Also check the backlight voltage with. You can also check the power and fuses on the T-con.

[smuddge]

Re: rca rlded5078a-d

full pic of all boards


bottom of power supply board

[CapLeaker]

Re: rca rlded5078a-d

Let's check the PSU. Disconnect everything from the PSU but the backlight. Take a 1k ohm resistor and jump 5vsb to PSON and Another 1k ohm resistor from 5vsb to BLon and plug it in. Everything should be alive and the backlight should be on. Measure all DC voltage rails and the DC voltages on the backlight connector.

[smuddge]

Re: rca rlded5078a-d

so let me verify. I am taking 2 1k resistors from +5vbs and running one of them to blon and one to pson.
only power and backlight cables connected?

If this is correct I did it and I still get nothing for display at all.
screen is black. can hear buzzing from power supply but nothing on the screen whatsoever.

[CapLeaker]

Re: rca rlded5078a-d

That's correct. You should see that all the voltage rails on the PSU are up and running. ALso the backlight if you have it plugged in should be on. The main board is disconnected.
Maybe you could post another pic from the PSU with the pin out without that foil? Can't see it good enough.

[smuddge]

Re: rca rlded5078a-d

ok here are all measurements i labeled all the connections 1-4
and this is the corresponding voltages for each

I added another full pic of the power supply board too.

thanks for all your help so far very much appreciated.
I am still very green when it comes to this just in case i sound like a moron.







connector 1
pin 1 11.75
pin 2 11.75
pin 3 0
pin 4 0
pin 5 0
pin 6 5.04
pin 7 5.04
pin 8 5.04
pin 9 4.95
pin 10 5.04
pin 11 5.04
pin 12 0
pin 13 0

connector 4
pin 1 .69
pin 2 0
pin 3 0
pin 4 0
pin 5 0
pin 6 0
pin 7 0
pin 8 0
pin 9 0
pin 10 0

connector 2
pin 1 23
pin 2 23
pin 3 0
pin 4 0

connector 3
pin 1 5
pin 2 0
pin 3 0
pin 4 0

[CapLeaker]

Re: rca rlded5078a-d

So far you are doing pretty good! So don't worry about being a bit green behind the ears...
Create a temporary short between BLon and ADJ, see what that does. 0V on the ADJ wont work.

[smuddge]

Re: rca rlded5078a-d

with the resistor still in place and shorting blon and adj I still get nothing coming on at all.

[budm]

Re: rca rlded5078a-d

What DCV do you get between the two legs of the main filter cap (the big long cap laying on its side) when PS-ON is applied? It should have >360VDC for the LED backlights driver to operate.

[smuddge]

Re: rca rlded5078a-d

380v across the large cap

[CapLeaker]

Re: rca rlded5078a-d

I see all the voltages are there, just nothing is coming out from the LED driver circuit of the PSU.
I found a PSU at tvparts.ca its a bit pricey.
Anyway... I guess you are down to check the LED driver. So check the 2 resistors, the 2 capacitors and the 4 diodes etc. Hopefully the transformers are not open. If you get to a part that is shorted in circuit, take it out and measure it again out of circuit.

[budm]

Re: rca rlded5078a-d

http://www.shopjimmy.com/proscan-ay1...upply-unit.htm
I will need the good quality pictures like the one by SJ to be able to trace out the connections in the LED Driver circuits.