Viewsonic VG191b

[retiredcaps]

Re: Viewsonic VG191b

UPDATE
I built my inverter and got the screen to work just meed to insulate it good
Total cost less than 15.00

Great Ingenuity! Congratulations!

[Lakerat]

Re: Viewsonic VG191b

UPDATE
I built my inverter and got the screen to work just meed to insulate it good
Total cost less than 15.00

[Lakerat]

Re: Viewsonic VG191b

I made my home made inverter and can see the the screen change shades and see lights in back of screen (did not reapply tape yet).
But no picture when when computer turned on but a steady green power light on front of panel... any idea on this?
Thanks

[Lakerat]

Re: Viewsonic VG191b

I just bought a case light and tested the lights with the power supply it came with.The power supply runs off a plug from the computers power supply and has 2 plugs for lights (was 5.99 at Frys).
Could I take 2 of these power supplys and run the 4 lights for the monitor off them would the monitor work if I did this?I would use the power that goes to inveter board to run both power supplys and they look to be the right size to go where the orignal inveter board goes. would this work?
Thx

P.S. link http://www.frys.com/product/5948774?...H:MAIN_RSLT_PG

[Rtech]

Re: Viewsonic VG191b

You will be very lucky to get a schematic for this,and suspect you are at the stage where to get the thing to work, you will have to replace the Inverter board with a good one.

[Lakerat]

Re: Viewsonic VG191b

I opened up my main monitor and A Viewsonic and made jumpers to try them.
I also noticed that I should recap my main before trouble happens it is 5 years old

[retiredcaps]

Re: Viewsonic VG191b

The lights test OK.

How did you test the lights to conclude they are ok?

[Lakerat]

Re: Viewsonic VG191b

OK with ohm meter on power side (input side ) of transformers I get 1 volt for the split second lights turn on when power switch is turned on

[Lakerat]

Re: Viewsonic VG191b

The lights test OK..... I put a meter across the ends of each transformers and get no readings but with power off I get the same Ohm readings for both.
So I think something that provides power to them is not working...
Where can I get a drawing on This board?

[Rtech]

Re: Viewsonic VG191b

Inverter PCB's are normally very difficult to fault find,if you eliminate the standard type faults,and so eliminating the CCFL's is really a prerequisite,and,like retiredcaps I have never used a Computer case lamp in this situation.The only other things you can try are resoldering of all the transformer pins,AND there are usually two 'coils' sitting on the board,and over time they can become dry jointed..so thats worth a try as well.

[retiredcaps]

Re: Viewsonic VG191b

I did a check on voltage on main board where ribbon goes to inverter board

#1 12 #2 12 #3 12 #4 0 #5 0 #6 1 #7 5.1 #8 0 I did these with neg side of meter using case for ground . I have one more monitor but ends are different on wires for bulbs. I read somewhere that you can use a computer case light to check black light bulbs. will this work?

Those voltages look like what I would expect from an external PS (assuming it is 12V DC). The 5.1 is pretty standard for use with the logic board.

I don't have any experience with the computer case light so I don't know if it will work or not.

[Lakerat]

Re: Viewsonic VG191b

I did a check on voltage on main board where ribbon goes to inverter board

#1 12 #2 12 #3 12 #4 0 #5 0 #6 1 #7 5.1 #8 0 I did these with neg side of meter using case for ground . I have one more monitor but ends are different on wires for bulbs. I read somewhere that you can use a computer case light to check black light bulbs. will this work?

[retiredcaps]

Re: Viewsonic VG191b

I have changed the small caps on inverter board not I can see both lights flash for a split second on to and bottom of screen....Since this has a external power supply and it plugs into other board and it is loaded with the crap X caps would could that be something to look at? power light stays on and for a few seconds I can see a image when power is turned on. I put a ohm meter at both transformers and got the same readings.

If you have an external PS, we are going to assume it is okay for now, because you get the backlights to flash on.

If the inverter transformers test okay and you see the backlights flash on for a second, then try testing the ccfl tubes to rule out a bad ccfl or ccfls.

[Lakerat]

Re: Viewsonic VG191b

I have changed the small caps on inverter board not I can see both lights flash for a split second on to and bottom of screen....Since this has a external power supply and it plugs into other board and it is loaded with the crap X caps would could that be something to look at? power light stays on and for a few seconds I can see a image when power is turned on. I put a ohm meter at both transformers and got the same readings.

[retiredcaps]

Re: Viewsonic VG191b

Ok here is what I tried... made a jumper for fuse (testing only) now when I turn it on I see the screen show Image of whats on computer for about 3-4 seconds then goes out what should I look for here?

Rtech makes good suggestions in post #13. More detailed instructions are in points #4 and #5 at

https://www.badcaps.net/forum/showthread.php?t=10419

[Lakerat]

Re: Viewsonic VG191b

Ok here is what I tried... made a jumper for fuse (testing only) now when I turn it on I see the screen show Image of whats on computer for about 3-4 seconds then goes out what should I look for here?

[Rtech]

Re: Viewsonic VG191b

It would simplfy the process if you had a spare good backlight ?????.The other things to try should you not have one,is to compare the resistance readings,using a 2000 ohm scale if possible, on the output pins of the two transformers.The Output pins being the ones closest to the ends of the board.Also the two capacitors behind the connector may be faulty,and of course your failed fuse.

[Lakerat]

Re: Viewsonic VG191b

Here is my photos of the board...sorry so dark

[Lakerat]

Re: Viewsonic VG191b

I know pictures will get them here tonight !! (I'm away from home M-F and camera is at my home)
I need a layout or schematic of the inveter board
T651008.00
I checked for the layout and found all others for this monitor but not for this board any help?
Thanks

[Rtech]

Re: Viewsonic VG191b

If the Power light comes on , then the Power Supply should be fine,and would not try and open that.The logical main culprit is the Inverter Board, as it is in the majority of monitors which have an external PSU,with a fault sympton like this.