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Old 03-28-2018, 10:20 AM   #1
soralz
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Default Viewsonic VA1912wb-4 after replace cap still not working

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?
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Old 03-28-2018, 02:01 PM   #2
neisg1
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Default 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.
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Old 03-29-2018, 01:43 AM   #3
soralz
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Default Re: Viewsonic VA1912wb-4 after replace cap still not working

Quote:
Originally Posted by neisg1 View Post
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.
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Old 03-29-2018, 07:50 AM   #4
neisg1
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Default 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.
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Old 05-15-2018, 06:16 PM   #5
starling22
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Default 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.

Last edited by starling22; 05-15-2018 at 06:18 PM..
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