Slight monitor issue. What is causing it?

[itobandito]

I have a monitor that was previously from a defender cabinet.   The whole cab was converted to a street fighter 2 machine.  The monitor in the cabinet looks absolutley awesome.  The colors and sharpness are great.  One little problem I noticed is everyonce an a while I get this small ummm.. I guess flicker.  The best I can describe it is it looks like its about to turn off, the screen shrinks a little.  When I say little I mean VERY little.  Do you think this is a power issue or do you think it just needs to be caped?

[grantspain]

could be a bad solder joint somewhere on the chassis,a failing electrolitic cap,a leaky transistor on the width circuit or at the extreme a flyback failing
also check the marquee light is not flashing as they can affect monitors depending how they are wired

[qrz]

if pic shrinks in all corners, may be pwr related. could even be another load on the same outlet circuit....
if shrinks vertically, then look in the vert deflection circuits .
if shrinking horizontally,  look for cold solder joint(s) on/near yoke connection to pcb , and hv areas ( flyback)

would be helpful to know if there is any unusual sounds coinciding with the occurance... ?

qrz

[itobandito]

Nope, no sound issues, I noticed that who ever wired this machine previously had it wired incorrectly.  They had the switching power supply, and the light running off the power the isolation transformer is putting out.  I am in the process of wiring these to a power distribution block.  Maybe that will help.  If anyone has any other input on what to look out for.  Let me know.

[qrz]

the smps provides isolation per design and would NOT need to be supplied AC through an xformer .
same with the marque lighting. no extra iso required...
the output voltage was likely fluctuating from the excess load .
this would cause the regulated supply voltage to momentarily drop in monitor .

supply raw AC to smps input, marque lighting and iso xformer (primary).
iso xformer (secondary) to monitor AC in


qrz

[sarge]

What model monitor do you have?  Before you go removing your isolation transformer from the circuit, you may want to make sure your monitor operates with a smps power supply or you may be setting yourself up to get a nice jolt off the frame of the monitor.

[qrz]

guess i was too vague.....

the monitor is the only item requiring mains isolation.....( DO NOT DEFEAT on non-smps types)
a switch mode power supply uses a transformer and thus provides mains isolation. ( game pwr supply )
flouresent lighting uses an "auto-transformer" for higher lamp boost voltage and is "HOT", but usually doesn't require mains isolation.

running everything through the xformer likely exceeds it's max load rating ... this will result in voltage drops and
high xformer temperatures , etc....

qrz