Sanyo DP-42849 backlight flashes on then stays off

[smkrchr]

My dad and I picked up a non-working Sanyo DP 42849 TV from craigslist a couple days ago. When we turn it on, after around 5 seconds, the backlight will flash on but immediately shut itself off again. We can see that the LCD panel is working when it flashes on.

We've been searching for similar problems for a while, so we already tested a lot of it. It appears that the main board works, as well as the transformer for the backlights.

A couple of the readings we got:
BL_ON: 3.3v
Transformer pins 5<->10 114.3 ohms
Transformer pins 6<->9 65.8 ohms

I don't remember the voltage/resistance readings we got for everything else, but I can re-do those and post what we got. My dad thinks that the problem is in or around IC301. We soldered a small wire to pin 16 (Vcc) and is it getting around 15 volts with the TV powered on.

The numbers on the power board are DPS-260LP, and on the mainboard are 1AA4B1ON22900_A

[smkrchr]

Re: Sanyo DP-42849 backlight flashes on then stays off

I found a datasheet on DDA002C, the chip on our board is DDA002B. Hopefully it's similar enough to do some more troubleshooting.

http://www.datasheetlib.com/datashee...conductor.html

I also thought I'd add that we do get sound from the TV, it's just the backlight that doesn't work. I am aware that there have been several threads with the same problem (and another new one as well). I have gone through them all but haven't been able to find anything that would help us fix ours.

[vinceroger69]

Re: Sanyo DP-42849 backlight flashes on then stays off

http://www.coppelltvrepair.com/p/429...-image-problem
have you tested the inverter transformers?

[smkrchr]

Re: Sanyo DP-42849 backlight flashes on then stays off

I'm not really sure the best way to do that. The backlight only flashes on a few seconds after the TV is turned on, so it doesn't seem exactly like most other symptoms. I've checked the resistance between pins with what others have reported on good transformers, and ours seems the same (114 ohms, 66 ohms).

[patrick89]

Re: Sanyo DP-42849 backlight flashes on then stays off

I have the same problem mine will flip on with the back light then shuts off. If I try this three times it will stay on for about a min but it will have a loud scream from the top part of the power board. Not sure what to do.

[jjaypops]

Re: Sanyo DP-42849 backlight flashes on then stays off

I am having the exact same issue. Any progress with the TV ?