ViewSonic VX2260WM not working

[robehickman]

Re: ViewSonic VX2260WM not working

The 8 connections listed previously are the only connections between the power board and logic board. Here's some more pictures.

[budm]

Re: ViewSonic VX2260WM not working

4.2V for the logic is too low. There should be 18~20VdC power supply also, this 5 and 20v are always on power supply. The 680uF 25V is the filter caps for the inverter circuit and it should be present.
Straight shot pictures of the board both top and bottom?

[robehickman]

Re: ViewSonic VX2260WM not working

From what I remember the monitor stopped working one day with the power light flashing, unplugged it and it worked fine the following day until it was turned off. It hasn't worked again since. I can't see anything from the back light at all.

The house RCD frequently trips whenever its raining or there are high winds, it may have failed after this but I can't remember for sure. I've had a computer PSU fail after it tripped, and the dishwasher's motor run cap failed recently after an RCD trip. Though those could just be coincidences.

Yes I have soldering equipment and can do through hole soldering, however I have no capacitors on hand and have no idea where to source components. I'm in Chepstow if anyone has any suggestions, physical shops or on-line.

The voltage across the big cap is 320v.

[selldoor]

Re: ViewSonic VX2260WM not working

Ok at least there are some voltages. Can you recall how the monitor went off. Did it just not turn on one day or did it deteriorate over time. Can you turn on in a darkened room to see if there is any flash at all from the backlights. Do you have soldering equipment and can you use it? Do you have any capacitors or a local source. We usually advise the use of panasonic fm caps if you can get them. We usually say to leave the BIG cap unless it shows any bulging or damage.

Can you carefully check the voltage across the legs of the big cap. All connected up
meter on 600vDC black probe on negative leg and red on the other leg.
Do not hold probes too near the ends voltage will be 220 to 400 volts.

[robehickman]

Re: ViewSonic VX2260WM not working

Power supply voltages are:

Pin 1 5v actual 4.2v[*]
Pin 2 5v actual 4.2v[*]
Pin 3 5v actual 4.2v[*]
Pin 4 5v actual 4.2v[*]
Pin 5 ground
Pin 6 ground
pin 7 on/off actual floats between 0.8v and 0v
pin 8 brightness actual floats between 0.8v and 0v
[*] starts at this voltage when the monitors power on indicator light flashes then slowly decreases to 0v over a few seconds until the light flashes again.

The power light flashes while the monitor is plugged in and does not respond to the power on button - it just keeps flashing untill the power is disconnected. Under normal conditions the power indicator light stays on continually.

Unfortunately I do not have any CCFL's or dead monitors around.

[selldoor]

Re: ViewSonic VX2260WM not working

Ok Ill take that as being 775 ohms and 780 ohms.Which is good.

With it all connected and on, what voltages do you get on the power supply out.
Use black probe on ground screw and work down the connector with the red probe.
Post as
Pin 1 5v actual 4.9
Pin 2 5v actual 5.1 etc etc.
Care although these are low voltages part of the board could be at 220-400 volts.

Do you have any spare ccfls or another panel (even a broken one might do.)

[robehickman]

Re: ViewSonic VX2260WM not working

Hi selldoor, the caps are as follows:

su'scon 2x270uf@50v, 1x47uf@25v, 2x220uf@25v
samxon 3x680uf@25v
The make/rating of the big cap is covered by the glue.

Yes I have a multimeter, the transformer shows 0.775 and 0.780 for those pins, not sure of it's orientation.

Thanks for your help.

[selldoor]

Re: ViewSonic VX2260WM not working

Hi - welcome to the forum. I can see that there are suscon caps on this board which is not a good start - are they all suscon if not what other makes.
Do you have a multimeter?
If so and while it is disconnected can you test the inverter transformer. Meter set on ohms 2000 test S1 to S2 and S3 to S4. Post the results.

[robehickman]

Hello everyone,

I have a ViewSonic VX2260WM monitor which stopped working months back, the power light blinks, quickly shutting off again and nothing else happens. As the PSU caps are a common problem with these things I've taken the board out, but there doesn't appear to be anything wrong with it, at least not visually. Have only a basic understanding of electronics so don't know how to test it.

The power here seams to be good at killing things, I've had several desktop power supplies fail on me also.