VX922 Contrast popping up and lowering it all by itself?

[lordgalla]

Hi guy's,I have done the repair on a Viewsonic VX922.Worked great for months,now all of a sudden the OSD contrast pops up on screen and lowers the contrast all by itself,and I can't stop it.If I shut down the monitor,hold power button for 30 sec. and then start up the monitor,it works ok with no problems for about 5min. or so and then the contrast pops up again,and lowers contrast,and I can't stop it,I can raise the contrast and as soon as I let go of the button,it lowers it all the way down all by itself?? any help much appreciated.Thankyou.

Had 1 bad cap bulging a C242 470uf 10v cap,I replaced it so far,can't find anything else wrong,all panel buttons are good,wiring to board ok.Anyone have a idea on this one? Much appreciated,Thankyou.

Other than that the rest of the monitor works great.

[momaka]

Re: VX922 Contrast popping up and lowering it all by itself?

If you replaced only one cap (in a monitor that is likely filled with other bad brands or more of the same), that's not a good thing.

Also, see my post here as I don't feel like retyping it:
https://www.badcaps.net/forum/showpo...6&postcount=23

[lordgalla]

Re: VX922 Contrast popping up and lowering it all by itself?

Hi,I replaced all the caps about a year ago,and it has been fine.It still is fine on the picture side of things and powers on ok,etc.Just started this new thing of the contrast popping up on the screen,and lowering all by itself.I noticed that 1 small cap swollen a little so I replaced it.

The contrast thing is the problem now all other things are working ok.Any idea's where to go here? Buttons all check out ok with ohm meter,on and off.

[momaka]

Re: VX922 Contrast popping up and lowering it all by itself?

Hi,I replaced all the caps about a year ago,and it has been fine.It still is fine on the picture side of things and powers on ok,etc.Just started this new thing of the contrast popping up on the screen,and lowering all by itself.I noticed that 1 small cap swollen a little so I replaced it.

The contrast thing is the problem now all other things are working ok.Any idea's where to go here? Buttons all check out ok with ohm meter,on and off.

It's best that you replace all of the caps, not just those that are bulging. Bad caps can cause all sorts of problems in LCD monitors - anything from no power and no video to distorted video, buggy menu buttons, flickering backlights, and corrupt firmware.

That said, post some pictures of the logic/video board in your monitor - it may have bad capacitors as well. Just because the capacitors look "okay" and have flat tops doesn't mean that they are okay. In fact, you should replace all obscure brands on your power supply (except for the large 400/450V cap, as that rarely fails).

You mentioned in the other thread that you have CapXon on your power supply board. CapXon is one of the worst brands of capacitors. Just ask anyone on the forum here . I did work on a similar FPS board awhile back (an FSP035-1PI01ZT) that had every CapXon capacitor blown. The video/logic board was also covered in CapXon, though those weren't bad (yet). Needless to say, I replaced everything. This was back in 2010 or so. Monitor still works to this day.

Lastly, I strongly suggest that you do NOT buy caps from eBay and Amazon. There are simply too many counterfeit and obscure brands there. The ones in your power supply with the "T" vents look like Panasonic, but I can't tell for sure, because the picture is too blurry. Panasonic are good capacitors... but that is only if yours are genuine. And on eBay especially, I can confidently say that a good 90% of the "good brand" caps sold there are counterfeit (particularly anything that ships out of East Asia). So beware of eBay and Amazon.

Since you are located in the US, Digikey and Mouser are the best options. The badcaps.net store may also have what you need, so check that too (and it supports the website ).

[R_J]

Re: VX922 Contrast popping up and lowering it all by itself?

Try disconnecting the cable that goes to the buttons, you can't really check for that problem with an ohm meter.

[lti]

Re: VX922 Contrast popping up and lowering it all by itself?

Buttons all check out ok with ohm meter,on and off.

What's the highest resistance range on your meter? The cheap ones measure up to 2MΩ, which might not be high enough, depending on the circuit. I have seen this happen to a different monitor before.

https://www.badcaps.net/forum/showth...081#post371081

[lordgalla]

Re: VX922 Contrast popping up and lowering it all by itself?

It's best that you replace all of the caps, not just those that are bulging. Bad caps can cause all sorts of problems in LCD monitors - anything from no power and no video to distorted video, buggy menu buttons, flickering backlights, and corrupt firmware.

That said, post some pictures of the logic/video board in your monitor - it may have bad capacitors as well. Just because the capacitors look "okay" and have flat tops doesn't mean that they are okay. In fact, you should replace all obscure brands on your power supply (except for the large 400/450V cap, as that rarely fails).

You mentioned in the other thread that you have CapXon on your power supply board. CapXon is one of the worst brands of capacitors. Just ask anyone on the forum here . I did work on a similar FPS board awhile back (an FSP035-1PI01ZT) that had every CapXon capacitor blown. The video/logic board was also covered in CapXon, though those weren't bad (yet). Needless to say, I replaced everything. This was back in 2010 or so. Monitor still works to this day.

Lastly, I strongly suggest that you do NOT buy caps from eBay and Amazon. There are simply too many counterfeit and obscure brands there. The ones in your power supply with the "T" vents look like Panasonic, but I can't tell for sure, because the picture is too blurry. Panasonic are good capacitors... but that is only if yours are genuine. And on eBay especially, I can confidently say that a good 90% of the "good brand" caps sold there are counterfeit (particularly anything that ships out of East Asia). So beware of eBay and Amazon.

Since you are located in the US, Digikey and Mouser are the best options. The badcaps.net store may also have what you need, so check that too (and it supports the website ).

Hi,the vid board ,the one where the DVI plugs in has like 10-22uf 25v caps and 1-100uf 25v and 2-330 16v caps.should I replace all of those to for this problem? they all look good,not swollen.Do you think this will help the problem I'm having? Thankyou for all the input.

[momaka]

Re: VX922 Contrast popping up and lowering it all by itself?

Hi,the vid board ,the one where the DVI plugs in has like 10-22uf 25v caps and 1-100uf 25v and 2-330 16v caps.should I replace all of those to for this problem? they all look good,not swollen.Do you think this will help the problem I'm having? Thankyou for all the input.

First try what lti and R_J suggested. If that doesn't work, post some pictures of your video board. It may be those bad caps, but it is better we see a picture first. Typically, it's the caps around the linear regulators that tend to dry out due to heat in that area.

But the PSU caps are still suspect as well, since you didn't replace all of them the first time.

[lordgalla]

Re: VX922 Contrast popping up and lowering it all by itself?

ok,here's some better photos of my Viewsonic VX922 power supply and video board.

[momaka]

Re: VX922 Contrast popping up and lowering it all by itself?

Ah okay, looks like you did do a full recap of the power supply board, and the capacitors you got from eBay do appear to be genuine Nichicon PW and Panasonic FR/FM/FC. So the power supply is okay.

As for the video board, looks like you have two Teapo SC (the green caps). Those are the ones that I would be most suspicious of. But in general, all of the caps around the regulators in this picture could be affected:
https://www.badcaps.net/forum/attach...7&d=1480215169

That said, I again urge you to try the tests that members lti and R_J suggested above... just in case this menu problem turns out to be a button issue.

[lordgalla]

Re: VX922 Contrast popping up and lowering it all by itself?

Hi there,Now what am I doing wrong now,It turns on ok,power light stays on,screen is bright white no signal on screen from pc at all.did not replace anything on video board,or the other board.Now I get nothing on screen.Man bumming me out now.Don't know what happened now? I wanted to try unplugging the buttons to see if it was a button problem,now I get nothing but white screen,green power button comes on ok,when starting pc,and stays on ok,but bright screen,and nothing on screen?

[momaka]

Re: VX922 Contrast popping up and lowering it all by itself?

Check LVDS cable connection between video board and T-con board. It's easy to forget to plug that cable in when you take apart the monitor and it's also easy to damage it if not very careful with it.

The T-con board is the one on top of the LCD panel, typically under a metal cover. Just make sure the contacts on the connector between that board and the video board is clean and the LVDS cable is plugged in fully.

[lordgalla]

Re: VX922 Contrast popping up and lowering it all by itself?

Checked all connectors all plugged in tight,I replaced those 3 brown caps on the power board with new ones with the T on the top,also the little cap behind the regulators.All values are right and installed correctly.Could this be a problem? the power supply? That is all I did,no other changes.I have not pitcher,and no menu at all.Just a white bright screen.

[lordgalla]

Re: VX922 Contrast popping up and lowering it all by itself?

Here's some more photos of those caps I replaced on the power board,3 4 I replaced with T on top ones.That was all i did to this.Now I get that white full bright screen and no display from computer,power light stays on green,no menu at all also.God help me,what am I doing wrong here? I just want to thank you for helping me through this,much appreciated.

[1supertech]

Re: VX922 Contrast popping up and lowering it all by itself?

Check for a fuse on the t-con board that connected to screen panel fuse should be near
the LVDS cable connector if it's their.

[lordgalla]

Re: VX922 Contrast popping up and lowering it all by itself?

Hi,don't see no fuse anywhere.

[lordgalla]

Re: VX922 Contrast popping up and lowering it all by itself?

No fuse on this one.I am wondering if I am pluging in the connectors on the video board to the logic board the right way? The dot on the connectors doesn't make any sense for pin one and so on,do you no what way these are supposed to go by wire color to pin 1 on the 3 different connectors to the 2 boards? The connection to the LCD at the top is clean and good connection.Still Nothing but White Screen,now what?

[lordgalla]

Re: VX922 Contrast popping up and lowering it all by itself?

Thanks guys,I am done.This video board is bad,not available any where online for this Vx922 monitor.Ebay etc. nothing anywhere.Not worth spending more time with it.Time to get rid of the rest of it.Thankyou all for your professional help on this.Unless you guys know where I can get a video board for this monitor with DVI and VGA connections on the board?

[momaka]

Re: VX922 Contrast popping up and lowering it all by itself?

Thanks guys,I am done.This video board is bad,not available any where online for this Vx922 monitor.Ebay etc. nothing anywhere.Not worth spending more time with it.Time to get rid of the rest of it.Thankyou all for your professional help on this.Unless you guys know where I can get a video board for this monitor with DVI and VGA connections on the board?

Sorry for the late reply. I hope you haven't thrown the monitor away just yet.

First, even if you do chose to not spend more time on it, it is still worthwhile saving the monitor for spare parts, especially the power supply - that power supply is used on some other monitors as well.

But if you do want to troubleshoot it, let me know.

There should indeed be a fuse on top of the T-con board, near the connector. It is SMD type, so it's not a "regular"-looking fuse. If the T-con board has designators, it will have a "F" prefix, followed by a number (i.e. F1, or F101, or F001, etc.) If that fuse is okay, then we have to check if power is getting to the T-con board. Since the video board was suspect to begin with, it is possible that it is not giving power to the T-con board.

So if the fuse on the T-con board measures OK, then recap the video board. Those green Teapo SC capacitors that can be seen in this picture
https://www.badcaps.net/forum/attach...6&d=1480521220
... are definitely the first things that should be replaced. Probably not a bad idea to replace the small caps around the regulators either. Only that way we know for sure that any problems this monitor may have are not due to bad capacitors anymore.

I hope this heps, and again sorry for the delay. I've been fighting with an LCD monitor myself in the last few days. I'll take a bad cap problem any day over replacing CCFLs again.