Viewsonic VX2235WM

[edharvey]

Hi guys

I have a Viewsonic VX2235WM which is very temperamental.
To get it to work you often have to unplug the power and then plug it back in, is this likely to be a cause of bad capacitors? This is not a backlight issue as when the monitor is working it is fine. Another thing I have noticed is when I switch it off the screen turns off and the power light switches off for a second and then stays on. I would have thought it was meant to flash when off?

Thanks for your help

[edharvey]

Re: Viewsonic VX2235WM

Just as an update, I have opened it up and identified several bulging CapXon capacitors. I will order and replace all of them on the board anyway I suppose.
Do I need to worry about leakage or ripple current when selecting new ones?
Also will it be necessary to replace the large capacitor next to 3 pin power input? It doesn't have a visible bulge.


Thanks again

[PlainBill]

Re: Viewsonic VX2235WM

Just as an update, I have opened it up and identified several bulging CapXon capacitors. I will order and replace all of them on the board anyway I suppose.
Do I need to worry about leakage or ripple current when selecting new ones?
Also will it be necessary to replace the large capacitor next to 3 pin power input? It doesn't have a visible bulge.


Thanks again

You need low ESR caps. I personally prefer Panasonic FM series, but there are other reliable brands and series. See the 'Which caps should I buy' thread in the FAQ.

There are two schools of thought on replacing the large cap. One group says that it rarely fails, so don't bother. The other school notes that 'rarely' is NOT 'never' and asks if saving $5 is worth the risk of having to open the monitor up again?

There are several possible approaches. I think there is already a thread for this monitor. If so, there may already be a list of capacitors. Verify that they match your monitor's. Quite often the same model monitor will have several different power supplies used in it.

A second approach is to list the following information: Capacity, voltage, diameter (if critical) for each cap, as well as the maximum height allowed. You can then use the procedure in this thread to identify suitable replacements. I suggest posting the results before ordering; sometimes an unsuitable cap is selected.

Or you can simply post the list and someone will suggest replacements.

PlainBill

[edharvey]

Re: Viewsonic VX2235WM

Thanks for your reply PlainBill, I replaced about 7 of the capacitors and now it works fine. Just wondering, is it likely for these to fail again? As in could there be another faulty component that caused their failure or is this unlikely?

Thanks again for your help.

[PlainBill]

Re: Viewsonic VX2235WM

Thanks for your reply PlainBill, I replaced about 7 of the capacitors and now it works fine. Just wondering, is it likely for these to fail again? As in could there be another faulty component that caused their failure or is this unlikely?

Thanks again for your help.

If you used good quality, low ESR caps (Panasonic FMs or others from the good caps list in the FAQ) a repeat failure is unlikely. The initial failures occurred because the caps were poor quality.

The most important characteristics for the output caps on a SMPS are ability to handle ripple current and low ESR (Effective Series Resistance). Heat is generated internally in the cap due to ripple current. If the ESR rises as a result, more heat is generated. This process continues until the cap eventually fails, often with a bulging top. A number of brands (CapXon, Lelon, Elite) are notorious for failing after several years. Panasonic, Rubycon, Nichicon, UCC are brands that do not have the problem.

PlainBill