Viewsonic VA1930wm Repair

[Welchs101]

Hi All,

A friend asked me to help repair his Viewsonic VA1930wm. WHen i first got the monitor it would not turn on. I opened it up and found several "bad" caps on the power supply board. So i replaced them.

I then powered on monitor and it powered on but the screen was all white. I then removed a few caps from the logic board and found that they were "bad" so i ended up replacing ALL the caps on the logic board........took me a while.

I then powered on the monitor and it worked! Well, almost. Monitor works great for about 15min and then i start to get these "horizontal" lines appearing ont he screen. I have enclosed a pic.........the pic is not that good but you can see faint images of the horizontal lines. The lines vary in placement on the screen from what i can tell. And the other thing is that when i first turn it on.....works great.......only after several min do i see such lines. SOunds like something is overheating but i am not sure what.

Any ideas?


I posted a few pictures of the logic and powersupply/inverter board.

Note: There are two caps in the inverter section of the board. They are radio shack caps. I did not put those in there my friend did. I already told him he should replace those with 105c caps but for the purposes of figuring out whats wrong with the monitor i have left those in for now.

Note: I know all the caps on the logic board were replaced as i replaced them myself. I dont know if ALL the caps on the power supply were replaced. I fairly certain that a majority of them were but i am not sure if ALL were.

any ideas what could be causing this problem?

[retiredcaps]

Re: Viewsonic VA1930wm Repair

SOunds like something is overheating but i am not sure what.

Try running it with the back cover off and a fan pointing directly to the power board first. Then try the logic board next?

[Rtech]

Re: Viewsonic VA1930wm Repair

I would also meter all the DC voltages including the voltage on the Main large Filter cap,and ensure there is no large variations.

[Welchs101]

Re: Viewsonic VA1930wm Repair

ok.....testing this thing when its on is tough given that all the boards are housed under the lcd panel and typically enclosed in a metal box but i figured something out.

I measured the DC voltage of the filter cap:
1) Monitor plugged in but not on: ~ 160VDC
2) Monitor plugged in and ON: ~ 152VDC


It took ~ 27min for the horizontal lines to showup after i turned the monitor on.


Note: The soldering around the transformer looked "bad" so measured the temp near it using a food thermometer..........see enclosed pic of exactly where i measured. Temp was ~ 115F and i think it would have gone higher if i left it there but rate of temp increase had slowed enough so i called it 115F.

The device 3055 was also very hot. Do you know what this part is? Datasheet?

[Welchs101]

Re: Viewsonic VA1930wm Repair

Searching through the bad caps forum i found this link

is this the right device for 3055?

https://www.badcaps.net/forum/showth...?t=7366&page=3

On page 2 of this thread. Stephkre and tglenchur post pictures of their board. They look exactly the same as my board. Their problem was the lamp........this does not seem to be mine as my monitor works for about 30min and then has the horizontal lines...........it could not be the bulb right?

[Scenic]

Re: Viewsonic VA1930wm Repair

your problem either points to the LCD controller board or the panel itself.
the PSU and inverter seem to work fine (backlight doesn't turn off)

edit: flaky connection of the LVDS cable? (the one connecting the LCD controller board to the panel)

[Welchs101]

Re: Viewsonic VA1930wm Repair

hi Scenic,

thanks for the reply. If it is a flaky connection......why does it work for 27min?

Is there some way to verify the flaky connection by measure voltages or something.

thanks again for the input.

[Scenic]

Re: Viewsonic VA1930wm Repair

dunno why.. maybe heat related.

i'd try to run the monitor with the back off. when it does those lines again, knock around the LCD controller board with the handle of a screwdriver (no metal parts please.. lol) or around the sides of the panel.
and play around with the cable going to the panel a bit..

watch if it has any effect on the picture while you knock around... and don't zap yourself

this monitor looks a lot like a noname "ProView 900P" (19" 1440x900 widescreen) that i fixed a looong time ago. had the usual crappy caps and bad (red tinted) CCFLs

it worked fine for about 7months after that repair (replaced CCFLs and caps), but then started showing random vertical lines on the screen..

turned out the panel itself was starting to go bad (connections inside the LCD Panel going from the little PCB on it to the actual screen. bonded to the glass. unfixable if you don't have the (expensive) tools to reattach them..)

[EGuevarae]

Re: Viewsonic VA1930wm Repair

this monitor looks a lot like a noname "ProView 900P" (19" 1440x900 widescreen)...

I agree.Looks like a 700/900P/G board. I had that problem once and it was a fluctuating 5v supply to the logic board (started to fluctuate after around 20 mins, when PSU overheated).

[Welchs101]

Re: Viewsonic VA1930wm Repair

what did you do to fix it?

[EGuevarae]

Re: Viewsonic VA1930wm Repair

what did you do to fix it?

I replaced all the PSU caps with 105C ones (had 85c).Once the 5v line was stable, the lines went away.

[Welchs101]

Re: Viewsonic VA1930wm Repair

ok,

I replaced the 85c caps with 105c caps. I plugged monitor in and it "seemed" to be better. I still had the "horizontal" lines on the screen but the quantity of lines seemed to have diminished......or it was just my mind wishing there to be a difference.

Anyway, i left the computer on by accident .........for 1 hour and when i came back the quantity of the horizontal lines seemed even less............so decided to leave it on for the remainder of the day. By the end of the day the lines had gone. Now i dont think this monitor is "fixed" i am just letting you guys know what happened. I would not consider this monitor fixed.

I am going to give this monitor back to my friend. I have done all i can do at my skill level. I will ask that he use it to see what happens. I fully expect the monitor to quit working at somepoint.


thanks for the suggestions.......as always you guys are great!

[Welchs101]

Re: Viewsonic VA1930wm Repair

Note: I had actually already given the monitor back to my friend when EGuevarae had suggested replacing the 85c caps with 105c caps. When i read this i remember from the post i read

https://www.badcaps.net/forum/showthr...?t=7366&page=3

what RTech said about the chips marked as "3055" that these chips run very hot. Well, the 85c caps are right next to these really hot chips........so changing the caps seemed like a really good idea.

Just an fyi.......

[alexanna]

Re: Viewsonic VA1930wm Repair

ok,

I replaced the 85c caps with 105c caps. I plugged monitor in and it "seemed" to be better. I still had the "horizontal" lines on the screen but the quantity of lines seemed to have diminished......or it was just my mind wishing there to be a difference.

Anyway, i left the computer on by accident .........for 1 hour and when i came back the quantity of the horizontal lines seemed even less............so decided to leave it on for the remainder of the day. By the end of the day the lines had gone. Now i dont think this monitor is "fixed" i am just letting you guys know what happened. I would not consider this monitor fixed.

I am going to give this monitor back to my friend. I have done all i can do at my skill level. I will ask that he use it to see what happens. I fully expect the monitor to quit working at somepoint.


thanks for the suggestions.......as always you guys are great!

On some monitors after a cap replacement I have noticed things similar to what you describe .Most of the time a good burn in corrects the problem