Viewsonic VA1912wb-4 after replace cap still not working

[soralz]

Hi guys, I am having a problem with my Viewsonic VA1912wb monitor. It can turn on and got image (can see it thru using flashlight), but the inverter was out. At first I thought was capacitor problem. And I found out 4 of the capacitors are leaked and bulged. Then I replaced all at the outputs area but after trying again the same symptom still occurs. The only capacitors I didn't replace is the big one and the 2 small ones in the middle, rated at 22uF 50v and 47uF 50v respectively. If I change those 2 will it assure the inverter will work again? If this fails I don't plan to invest anymore on it. Or is it probably the primary capacitor fails?

[neisg1]

Re: Viewsonic VA1912wb-4 after replace cap still not working

Some boards have a small pico fuse near the inverter. Could be the other 2 small caps also check the inverter transformer 2874005300m. With the power disconnected use a multi-meter the coil on the primary side should read close to zero maybe 1 or 2 ohms. The two secondary side coils should each read between 1k and 2k ohms and should both read the same. That transformer is available on eBay for under $10.

[soralz]

Re: Viewsonic VA1912wb-4 after replace cap still not working

Some boards have a small pico fuse near the inverter. Could be the other 2 small caps also check the inverter transformer 2874005300m. With the power disconnected use a multi-meter the coil on the primary side should read close to zero maybe 1 or 2 ohms. The two secondary side coils should each read between 1k and 2k ohms and should both read the same. That transformer is available on eBay for under $10.

Alright I checked the transformer it got 8 pins, 4 connections it reads 750 ohms for both the top and bottom ones. The middle two shows 0.2 ohms.

[neisg1]

Re: Viewsonic VA1912wb-4 after replace cap still not working

My transformer is a similar type but different part number. My bad one read about 0.1-0.2 ohms on the primary side. One winding of the secondary read 1020 ohms the other was 848 ohms. When I opened it up the 848 ohm side had burn marks. Yours must be a bit different specs. but as both secondary windings show exactly the same at 750 ohm i wold assume it's is ok. Not likely that they would both fail with the same 750 reading. I ordered a new one but don't have it yet.

[starling22]

Re: Viewsonic VA1912wb-4 after replace cap still not working

Just of curiosity, what happened hear? success
I am just starting to look at my va1912wb which has symptombs of capacitor problems, takes long time to turn on and clicking sound with flashing green light.

[starling22]

It appears I must have fixed my Viewsonic back 6 years ago, probably replaced caps, because it has worked well till this week. now it is failing, I think it is just the back lighting.

Power LED comes on but no other screen activity. As it is part of a two monitor setup the second screen has provided interesting information.

If I remove the signal cable all the icons on the dead screen assembled in the second monitor and system working [in a fashion, but too many icons to wade through]

Power down and reconnect the signal cable and power up again, the invading icons on monitor 2 goes back to the dead screen.

I have concluded that back lighting is not working, I am however convince completely so I am prepared for surprise.

I will work through this topic from the beginning. Suggestion though welcome.

I have the service manual as well, so off to good start and have the unit dismantled.