What's wrong with my Pac Man (pics inside)?

[Wavelflack]

I'm pretty sure this is not a board related issue, as I have swapped out boards in the cabinet (yes, I had 2 good ones), and I eventually have the same result.

I had guessed it was a Hsync wire loose/bad solder joint/bad pot, but after wiggling this and that, I can't manage to make a difference.
Here's what happens: You fire up the machine, and it plays fine. Lately I've noticed a little more pronounced vblank line moving across (slowly), but I attribute this to having jiggled this and that (including pots), and figure my hold is out of whack. maybe not. Anyway, it plays fine for a random period of time (though with hum...too lazy to change out caps), and then the screen will "warp" (bend and distort) for a second, and a little while later, I have a very reduced screen! A little while later it goes completely to a vertical (horizontal, I guess) line. Everything operates as usual, but it's compressed to a slot.

Sometimes it skips right over the distortion and intermediate size, and goes straight from fullscreen to line mode. Sometimes it takes an hour, sometimes less than a minute. This is without touching the cabinet, BTW. It's not a minute if I bump it, and an hour if I don't. It's completely random, regardless of what you do (though if you whack the cabinet good, the sooner it seems to happen).

Any ideas? Pictures of the three stages follow:

http://www.photodump.com/direct/wavelx/before.jpg
http://www.photodump.com/direct/wavelx/during.jpg
http://www.photodump.com/direct/wavelx/after.jpg

I hope someone can help! This has been driving me nuts off and on for years!

[Wavelflack]

Oh, and it doesn't "shrink". By that I mean that you don't see it reducing. It doesn't get smaller from A to B to C. It starts one way, then BAM it's either 1/8th width, or just a line representing the whole screen.

[y-bot]

something here might be helpful:

http://users.erols.com/mowerman/pacfile.htm

and I'm still looking for another website that I don't know the name of.

here's another one but I can't find the one I was looking for.

http://www.twobits.com/humbar.html

you might want to check other pages on that site. I had to replace the connector that goes on the edge of the PCB on my Pac-Man. I still have some monitor problems though (white lines on the right side). I've given up until I replace the caps and start from scratch someday.


y-bot

[Flack]

I had a game doing the same thing and was told that a monitor cap kit would definitely fix the problem. That's where I'd start, for sure.

[leonk]

I strongly recommend a cap kit.

I had a cab made in 1994 (much newer than yours) and it had all kind of problems on screen. The moment I installed a new cap kit.. it all came back to brand new condition. Truly amazing.

You should visit arcadecontrols.com. Check the arcade video forum there.. there's some really knowledgable arcade/tv repair guys that can even tell you what capacitor on your monitor is gone! 8-)

[y-bot]

I just thought of something else. Try unplugging the PCB and see if the monitor does the same thing when you turn it on. Just so you can be sure it is the monitor and not something else.

y-bot

[FABombjoy]

That's called "horizontal collapse" and a cap kit may help. If it's never had a cap kit, it's probably time. 99% chance it's the monitor, not the game PCB.

[Arcade Antics]

Yup. Cap kit.

Even without the horizontal collapse, the monitor is badly in need of a cap kit, it's particularly noticeable in the lower right corner of the screen.

You can get the kits for your monitor (and tons of other replacement parts) here, should run you between $5-$10 and it'll make your monitor look brand spankin' new.

http://www.therealbobroberts.com

[Wavelflack]

Excellent. Thank you all for the info. I'll be glad to get that thorn out of my side.