Digihome 37" 37723 HD

[tom66]

Will be picking this up later tonight.

It has no picture, that is the description. I expect it will be the typical 15nF cap failure (Vestel rubbish PSU.) May just replace the PSU if it proves too difficult.

[tom66]

Re: Digihome 37" 37723 HD

So, got it home. Vestel trash again.

Immediate diagnosis is a brief WHITE flash from screen then backlight shuts off. Otherwise, set behaves normal - turn on/off fine. Not tested sound, expect that may be okay.

Now if the screen flash were grey (as in no signal but backlight dying) I would say it is likely an inverter issue. But it's white, indicating the T-con is also not getting proper power.

Put the scope on the 24V line and when the backlight flickers the 24V drops by 1.5V quickly, probably enough to upset the inverter board. The 5V may do the same thing, haven't tested it, but if it is, it's likely the problem.

I'm going to try to repair this PSU instead of just swapping it out. Wish me luck.

[tom66]

Re: Digihome 37" 37723 HD

Well, I ordered some 15nF caps cheap. But, I just went and checked the inverter. The INV_ON stays on (3.3V) when the backlight goes off. So, checked the transformers, sure enough one is high in resistance. Strange the screen flashes white - there could be a second fault here - or maybe it's so quick I can't see anything on the screen (or it could be snow.)

[tom66]

Re: Digihome 37" 37723 HD

Video of diagnosis:

http://www.youtube.com/watch?v=Wv8Hj...ature=youtu.be

[tom66]

Re: Digihome 37" 37723 HD

It's fixed now, it was the transformer. Unfortunately it appears that the screen has some mura in the top corner. This is fixable but I may just sell it as-is as it's not particularly noticeable. It has a CPT (Chungwa Picture Tubes) LCD panel, which is crapppp, so that's probably the reason. Also awful motion blur and crappy contrast.