Stumpped on a ViewSonic VP930b

[alainski]

I've repaired two VP930b already but this third one is giving me a doozy.
All three monitors have bad caps. I've replaced all caps except the big CapXon 100mF; 400V.
The third monitor remain no power.
The fuse is not blown but there is no output voltage on CON2 connector though.
The monitor works when I install the other repaired PSU.

I've double checked the solder and now I'm stumpped.

Any inputs are appreciated.

Thanks!

[Longbow]

Re: Stumpped on a ViewSonic VP930b

So by saying you don't have 400 volts you mean that you don't have any primary side B+ ???

[kaboom]

Re: Stumpped on a ViewSonic VP930b

Replaced capacitors- with what type? I see two Nichicons but can't tell what series. I can just make out the "1" of the 105 degree marking.

Those four blue caps look cheep 'n nasty- NTE are they? They look more like cheapo teapos... Is C7 on the primary side a Panasonic FC?


As for no primary B+, check the fuse, thermistor and rectifier. Also look for and repair bad solder on the AC inlet and filter chokes. Check the line switch for continuity. In theory, the DC voltage across that big cap will be the RMS line voltage * 1.414. Of course, regulation under load will make it drop a bit.

-Paul

[alainski]

Re: Stumpped on a ViewSonic VP930b

@Longbow - I do not know which point my meter would read 400V
@Kaboom - yep, NTE they are. Fresh out of 16v 1000mF so I had to run at Fry's. C7 is Nichicon. All are high temp caps.

The board is now fixed though. Followed Kaboom's advise of checking continuity and bad solder joints on other components.

3x magnifying glass is not cutting it anymore.

Thank you all!