Wells-Gardner U5000 problem

segundosombra

Cheng's Errand Boy
Joined
Jul 29, 2004
Posts
114
Hi everybody.

I need help with my Wells-Gardner monitor. It is the U5000 model and it can not display correctly the image. Picture seem to be a vertical wave at both sides.
So I recently changed the swollen C115 cap (100uf, 200v) by other with the same specs, but monitor wont to sart. Nothing is working.

But if I remove the new cap then I can notify the psu is working nevertheless.

If anybody knows how to fix this problem, please let me know.

Thanks in advance.
 

segundosombra

Cheng's Errand Boy
Joined
Jul 29, 2004
Posts
114
First, many thanks for the reply tody. You are always helping me to fix any thing and... impossible to know. I don't have that cap. Any other tip?
 

ttooddddyy

PNG FTW,
Joined
Nov 29, 2001
Posts
8,335
Another question, did this monitor have the "vertical wave" ever since you have owned it ?? This is important to the diagnosis.
 

segundosombra

Cheng's Errand Boy
Joined
Jul 29, 2004
Posts
114
I can't answer that question because I purchased the monitor a few weeks ago. But for some reason monitor works fine now... and without that cap. So my question is what if I remove definitively that cap?

Thanks
 

ttooddddyy

PNG FTW,
Joined
Nov 29, 2001
Posts
8,335
segundosombra said:
I can't answer that question because I purchased the monitor a few weeks ago. But for some reason monitor works fine now... and without that cap. So my question is what if I remove definitively that cap?

Thanks

If it works thats fine leave it as it is
. Anyone with a link to a U5000 schem, would be interested to know the function of that cap.

Its value (given 110 volts mains) suggests the rectified mains smoothing/filter cap, which if faulty could have caused the hum you described.
But for it to work fine with the cap removed - I have no explaination for that.

Post a piccy of its location, that may help solve the mystery.
 

segundosombra

Cheng's Errand Boy
Joined
Jul 29, 2004
Posts
114
Sorry for the delay in response. Here are two pics.

16.jpg


17.jpg


If you need pics of entire board, please let me know.
 

channelmaniac

Mr Neo Fix-it
15 Year Member
Joined
Nov 29, 2005
Posts
4,275
C115, that is your main filter capacitor. I'm surprised it's running worth a crap without it.

There's no reason for it to cause the supply to not work unless the replacement is shorted or was inserted backwards.

RJ
 

ttooddddyy

PNG FTW,
Joined
Nov 29, 2001
Posts
8,335
In theory you should get at least a nasty 60 Hz hum with the filter cap missing, if it worked at all. The original may have dried out but had some capacitance.
The fault symptom you described is what you might expect.

What I thought at the begining of this thread was that a previous owner may have turned the +B up to cover the effects of a faulty filter cap (low capacitance) and when it was replaced the rectified mains would have been restored leading to an increase in +B which may have caused the over volts protection to shut the monitor down.

Just a thought.
 

channelmaniac

Mr Neo Fix-it
15 Year Member
Joined
Nov 29, 2005
Posts
4,275
That is a good thought.

One thing though... that is a switching power supply so it won't have a 60 cycle hum to it. It's probably switching at around 12KHz or faster. The cap is on the output of the switcher and not the mains side.

RJ
 

ttooddddyy

PNG FTW,
Joined
Nov 29, 2001
Posts
8,335
Yep- I glanced at the 4 diodes and thought I was looking at the primary bridge rectifier, doh ! Keep your eyes peeled Toddy :eye: :eye:

With the +B smoother missing there should be a noticable effect, like squiggly verticals.
 
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