Viewsonic VP201b service manual??

Finding service manuals / schematics for LCD monitors is pretty difficult.

I have several of these monitors (including the one I'm using as I type) and got to know it's layout quite well. I'm a little puzzeled by your description of the problem. Could you explain in more detail?

One place I repeatedly suggest people with monitor problems visit is

PlainBill

I will have to see, when I get it in front of me, but I was told that the picture rolls from top to bottom.

Anyway, I will get it in a couple of days, so I can give better description.

-Jan Finland

I finally received this monitor and when I plugged it in, it worked perfectly. I decided to open it anyway, since I have been reading a lot about bad caps in Viewsonic's. I found that the main 400VDC filter cap was totally off from PCB on the + side and one dry joint on one of the power transistors. So, after few days of burn-in, it seems to fine. Thanks for pointing me right direction.

-Jan

The original problem has come back, I guess the faults that I fixed, were not the correct ones. Here is a video of the fault, which seems to come and go:

-Jan

I would look for other bad caps in the power supply. Even the one you mentioned could be open-circuit. I often see caps in the 1000 to 2200 uF range bad, often with vented (bulged) tops, and more and more seeing the input filters (ex 150uF at 250 volt) snap-in types bad. Cheap crap...

Mark Z.

I ESR'd all the caps on power supply PCB and they tested out fine. Also, no leaks or bulges.

-Jan

A shame you didn't say so previously...

mz

Are any of the caps in parallel? If so, one or more could be open, yet you still read a decent ESR from the good ones.

Well, sorry about that.

Also the fault seems to have something to do with contact, since giving the display a slap on the top left corner (while the display goes crazy) makes it return to normal...

-J-

Try re-seating the connectors in the sensitive part of the panel.

I'd still watch out for that main filter cap; I've seen them be intermittent... and given that you saw a problem there I'd certainly keep it in mind.

Mark Z.