monitor just stopped working

[redfivexw]

hi everyone,
i have a rolling thunder machine, with a wells-gardner monitor.  It was working fine for several years and looked good.  I recently moved it to the other side of the room and when i turned it on, the monitor does not work.  I dont hear anything coming from it, no orange glow on the back, not the normal noise you hear when the monitor gets power, i checked inside and dont see any loose connections.  Anybody know what could make it stop working so suddenly? 

[Ken Layton]

What model? Wells-Gardner has dozens of models.

Here's what to look for in general:

When you moved the game, did something come unplugged/unconnected?

Did something come loose and fall on the monitor circuit board thus shorting something out and blowing a fuse?

Did you bump/jar/crack the neck of the picture tube or the neck circuit board?

How old is this monitor? Has it had a capkit recently?

[redfivexw]

I will check the monitor model number shortly, I do not see anything that could have fallen on the board, actually it is quite clean inside.  I have not had anything done to this monitor, it is a 1987 machine, i think it was pretty much stock equiptment.  The glass all looks good, no cracks or problems i can see.  As i said, it had a good picture, working fine for 2 years in my house, i moved it and when i plugged it back in, just black.  the game itself is working, but no picture.  It is as if it is not getting power, but everything else works. 

[redfivexw]

The model number is WG  19K4914.  While i was looking for the model number i noticed a fuse on the board that looks like it might be no good.  It is covered with a plastic shield so it was hard to tell but i think that the strip of wire in the center was broken.  The fuse is labeled F501 4A 125V.  It looks like it is soldered in.  It is the only fuse i see, could this be the likely culprit?  If so, what is the best way to replace it and what size fuse is it?  Can i just unsolder the fuse and solder a new one in? 

[Ken Layton]

I believe it is a 4 amp fast blo 'pigtail' fuse. Yes, you unsolder the bad one and solder in a new one.

[Raven..]

Ken,
Do you have to remove the chasis to replace the fuse, or can it be done in place (with the power off, obviously)?

[redfivexw]

yes, i was wondering the same thing, i am planning on doing it in place, i think i can reach it pretty well. 

[Ken Layton]

The circuit board must be unbolted and flipped over to unsolder the fuse.

[redfivexw]

Ken,
i soldered in a new fuse, it blew immediately.  I tried 2 more and the fuse blows immediately upon turning the machine on.  Any idea what could cause this, as i said before, the machine was working fine, there is nothing loose, nothing on the board, I am at a loss.  I have one fuse left, what should i check?

[phildo77]

That sounds a lot like a short somewhere.  Check for leads on components that may be bent over and/or barely touching something they shouldn't.  Could also be a blown component somewhere.  Look for brown tainted components (and possibly smoke stains on the board.)

[redfivexw]

there are no stains on the board, the board looks good.  This is really weird, and frustrating. 

[Ken Layton]

It could be one of the following:

Shorted horizontal output transistor

Bad flyback transformer

Shorted power supply section diode

Shorted voltage regulator in the power supply section