Screen going red?

[StanJr]

I turned on our Pac-man upright tonight and for some reason the screen is tinted red. It will flicker a bit and act like the red tint in going away, but it does not and the screen remains with the red tint. The display is still crisp and the game plays fine.

 

What is going on and how do I fix it?

[Rybags]

Maybe green or blue has dropped out?

 

No idea if the old games used RGB, but one colour becoming dominant is often a sign that one of the others has dropped out.

[TheBman80]

Here I think the answer is on this web page you should bookmark it for future repairs. http://www.arcadegameover.com/pactrouble.html

According to the web page there are several reasons the screen goes red take a look and see which most resembles your problem.

[StanJr]

this one looks like me:

 

"Light red haze over entire screen.

 

Signal from 4A p11 to 3A,3B p11 high.

 

Signal from chip 3B p9 to 7F p11 is high."

 

 

 

 

 

But I have no idea what that means or how to fix it...

[chadtower]

Signal from 4A p11 to 3A,3B p11 high.

 

 

The signal going from pin 11 on the chip at position 4A to pin 11 on the chips at 3A and 3B is not cycling properly and is stuck at the high end of the spectrum.

 

 

Signal from chip 3B p9 to 7F p11 is high."

 

 

The signal going from pin 9 on the chip at position 3B to pin 11 on the chip at position 7F is not cycling properly and is stuck at the high end of the spectrum.

Edited November 1, 2006 by chadtower

[TheBman80]

Yeah, I’m not to sure myself I haven’t had a chance to work on PCB's yet maybe replace the chip having the problems would help. I have 2 Pac man’s to fix myself but need a multimeter before I start. This seller sells ROM chips on eBay you might want to ask him if he can just burn you the chip in question if that’s what you need. http://cgi.ebay.com/MIDWAY-PACMAN-New-Comp...1QQcmdZViewItem

[chadtower]

Those chips are almost certainly not ROM chips.

 

And often, the reason the output from a pin is stuck high is because its input is stuck high. Those aren't solutions, just places to start looking.

 

Odds are, the red drive transistor on his monitor chassis has shorted. I'd look at the monitor itself as the issue way before the boards.

[TheBman80]

Well if you ever need the ROM chips there’s a good source I was just looking at the ROM locations and was just about to correct myself.

[chadtower]

Start simple. Reseat all of the connectors, including those within the monitor chassis, and see if that makes the problem go away.

[StanJr]

thanks guys. I'm also getting some help from Arcade expert Cassidy Nolen, so with luck the problem will be righted before next week!

[Cassidy Nolen]

FTWIW,

 

I'd look at the monitor itself as the issue way before the boards.

 

Most of the harnesses hang funny on those monitor pins and I am fairly sure its a cold solder/trasistor issue. Should be very easy to diagnose.

 

C

[chadtower]

Most of the harnesses hang funny on those monitor pins and I am fairly sure its a cold solder/trasistor issue. Should be very easy to diagnose.

 

 

The neckboard being on crooked or loose is certainly a possibility. Monitors of that age have cracked neck pins or cold joints on the neck board all the time. Of course, with a monitor that old, you're playing with fire just to remove the neckboard. More times than I want to remember I've pulled a neckboard only to have half the pins come off in their sockets.

[TheBman80]

Could it possibly need a cap kit if it’s the original monitor I don't think it would hurt would probably brighten the monitor up a lot color wise. If the wire thing doesn’t work out that might be the next step that can usually fix a whole lot of monitor troubles. Just watch yourself poking around that monitor tube especially if your just resetting wires you could still get a nice zap make sure it’s unplugged. I got a small zap once it wasn’t an enjoyable experience.

Edited November 2, 2006 by TheBman80

[chadtower]

Erm, if he doesn't already know what to touch and what not to touch, he should get the hell out of the back of his cab. The charge in a 19" CRT is more than small. It can cause permanent nerve damage and possibly if shot somehow directly across the heart may be enough to stop it. Monitors are not for newbies.

 

As for a cap kit, if it has never had one, it 100% certainly needs one.

[TheBman80]

Yeah I know what to touch and not to touch in a monitor but man if I wasn’t surprised when an ark of electricity came right out of the tube itself and hit me from like 2 inches or so away got to love those Vector monitors.

[chadtower]

That should never happen with proper practices. You were doing something you shouldn't.

[TheBman80]

The monitor did have some issues though so it wasn't totally my fault I decided to leave it alone until I could get a multimeter and a HV probe got the probe just need the meter.

[chadtower]

Don't need the HV probe, really. If you get HV whine, which you can hear, you have HV.

[TheBman80]

Oh I got it so I can later discharge the monitor and recap it I have a few that need it so I thought it was a good investment so I didn't kill myself accidentally. I heard the screwdriver and a cap works with some alligator clips but I think having the right tools for that kind of job was worth it to me. Plus the advantage a high voltage probe has over the screwdriver method is that you can see the voltage reading on the multimeter and know it’s safe. But back to the issue at hand any luck yet on the red screen problem? Have any pictures of the screen?

[chadtower]

If you're going to do it more than a couple of times, yes, an HV probe can be a worthwhile investment. I usually use a screwdriver and alligator clips myself.