Galaga Hum Bar/Blurry Until Warmup.

[Witchboard]

I have a friend who purchased a Galaga cocktail.  When he first powers it up, he has a hum bar and the picture is blurry.  After 20 minutes or so the picture is crystal clear and the hum bar is gone.  It looks as though somebody recently did a cap kit on it and the flyback looks new.

He was having some reset issues so we checked the power board and found a cold solder joint at one of the large caps.  We reflowed a couple of other questionable joints and his reset problem was fixed.  He says it's always had the hum bar/blurry problem though.

Should we redo the cap kit or maybe look at testing the tube on a rejuvenator?

[SirPeale]

Hum bars are usually caused by power issues.  I'd investigate your grounding.

[Witchboard]

When he bought the cabinet they had cut the ground off the plug.  We replaced the power cable with one that has a ground.  Didn't correct the issue.  Kind of odd though that the hum bar goes away after the system warms up.  Sounds like a failing component or a cold solder joint.  We'll look at some more grounding. 

[modessitt]

Recap the monitor if it hasn't been done yet.

Replace all the fuses with new fuses and clean and "tighten" the fuse clips.

There is a hum bar repair info page for Pac-man and Ms. Pac-man games, and since Galaga and Ms. Pac cocktails (and uprights) are basically the same, this could help you solve your problem.

Having the picture stay blurry could be a cap fix, but may be a sign of a failing flyback, too.

[Witchboard]

I had him ask the guy he bought it from if they had done a cap kit.  The answer was no, so we're going to recap the monitor.  Hopefully that will fix the fuzziness.  I'll have him reflow the flyback.  I'll do a search for the hum bar info page.  Thanks.

[slider2732]

To follow from modessit's info Mr. Witchboard...

Here's a kit for the all in price of $15, that will fix Pacman hum bar trouble, but the accompanying info was perhaps of interest.
The link is an Ebay store sale:
The longest eBay URL I've ever seen

A section of the info reads:
"This problem is associated with the power supply section of the game board and assumes that your cabinet edge connector and game board edge connector are in good condition with no burned traces or crushed pins. This kit also is designed to repair common audio problems on these game boards. The kit has 11 capacitors"



A great page all about hum bar effects and how to resolve them is here:
http://digitalcontentproducer.com/mag/avinstall_losing_hum_bar/

[Witchboard]

He did the cap kit and no change to the monitor blur.  He replaced the pot on the power board which seemed to be faulty since it did not change the voltage.  It was running over 6V on the 5V line.  Once the pot was replaced and the voltage adjusted, the hum bar is gone.  He's going to replace all the caps on the board.  He's going to reflow the flyback and see if that will correct the fuzzy monitor.  If that doesn't work, we're going to test the tube on my rejuvenator.

[modessitt]

you can try the focus test on the rejuv, but as your focus control is on your flyback, that could be your problem.

I know this is a simple question, but have you removed the glass from in front of the monitor and cleaned the tube and the bezel glass?  If a game has had a hard commercial life, it could have quite a layer of cigarette residue on the screen, making the picture look fuzzy.

Another think to think of would be really bad burn-in.  When the game is off, can you see the image of the screen in the tube?  Really bad burn-in can cause fuzziness around the edges of the picture in some cases.

[Witchboard]

Yeah, the glass had to be removed to repaint some flaking.  I'm presuming he cleaned the tube when doing so.  There is some slight burn in where you can see "Insert Coin" but that's about it.  I wouldn't think that burn in, nor smoke would clear up after the monitor warmed up though.  After about 20 minutes it's crystal clear.