Viewsonic VX1962 noisy when updated

[geertd]

I bought this monitor a long time ago. It always worked fine, but last week it started behaving strangely:

This is a secondary monitor on a two monitor system that runs Linux Fedora 22.
The primary monitor is connected via HDMI, the secondary one (the viewsonic in question) via DVI cable. Both are connected to the same video card.

Since a couple of days, the screen works fine as long as the contents shown on the screen are not modified. As soon as its contents are changed (like moving a window or changing its content), it gets noisy for about 2 seconds after the change, than works fine again. The noise shows a pattern of vertical noisy lines over the whole screen. During this time the screen contents remain readable. This only happens on the viewsonic. The primary Samsung does not have this problem.

To make sure this is not a cable or cable contact issue, I changed the DVI cable and connected the monitor with an analog cable (DSub). This did not improve this noisy behaviour.

I wonder if this could be a capacitor issue, since I could not find other posts describing the same behaviour as above.... ??

Regards,
Geert

[stj]

Re: Viewsonic VX1962 noisy when updated

it probably is a cap, but it could be on the mainboard or panel.
it sounds like a panel bias voltage is not right.

[CapLeaker]

Re: Viewsonic VX1962 noisy when updated

open it up, have a look and post some pictures.

[geertd]

Re: Viewsonic VX1962 noisy when updated

OK, got another little task for the weekend. I first posted my problem in case someone has seen this problem before and would point to something else instead of bad caps...

Geert

[geertd]

Re: Viewsonic VX1962 noisy when updated

So,

I opened the viewsonic, and did not see anything that points to bad caps. See attached pictures,

Assembled the monitor again and I still have the same problem, although it looks as if now the screen noise is more horizontal than vertical

Geert

[stj]

Re: Viewsonic VX1962 noisy when updated

you cant see bad caps unless they are large.
you need an ESR meter.
although as small caps cost about 15c for decent ones, it's cheaper just to replace any you suspect.

[budm]

Re: Viewsonic VX1962 noisy when updated

http://s807.photobucket.com/user/bud...?sort=3&page=1
Recap the board (including the very small lytic cap in primary side) before it is too late and take out the power MOSFETs that drive the inverter transformer.

[CapLeaker]

Re: Viewsonic VX1962 noisy when updated

a bad cap doesn't have to "look" bad. It can look good and still be bad. So replace them either all, or those that have bad esr.

[momaka]

Re: Viewsonic VX1962 noisy when updated

I opened the viewsonic, and did not see anything that points to bad caps. See attached pictures,

As the others said, the caps don't have to look obviously bad to be bad.

Moreover, you have CapXon caps on your power supply, which is one of the worst brand. My recommendation is to replace all of the CapXon caps except the very large 400V one (that one rarely causes problems and is usually also pricey).

Lastly, post a picture of your video/logic board (the one that attaches to teh power supply board). You may have more bad caps there (that don't necessarily look bad again). Sometimes, the manufacturer will place those small caps next to a hot linear regulator, and they will slowly dry over time and fail without any visible sign whatsoever.

[geertd]

Re: Viewsonic VX1962 noisy when updated

just ordered new caps. Will post result when replaced