Blue haze over monitor, time for a cap kit?

[InsaneDavid]

I have a Wells Gardner 19K7901 in my newly acquired Klax cabaret that has had a problem since getting it home. From time to time there's a blue flicker and haze across the entire display. Everything can still be seen behind, it's like a blue overlay. It seems to be completely random when it comes up. From time to time the flicker intensity increases and the entire screen glows blue with some diagonal lines across it. However the game can still be seen behind it. The washout looks like this...

http://www.classicplastic.net/digitalpress/monitor01.jpg

The lines don't move, they're just there and the blue then flickers away until it flashes up again. Sometimes it's frequent, mainly it's every 20 minutes or so give or take. I've disconnected and reconnected the usual suspects, checked the JAMMA harness, and adjusted the monitor pots. Without the blue the monitor looks great, true colors and no distortion (since turning the brightness down a hair and the focus up recently).

Would a cap kit be the next route or is there something less involved that I can try before? Any information on what the cause of this would be? My brother had a TV that did this same thing last year (except it was red) and eventually it got to the point where it would turn itself off, and then not turn on anymore. I'd like to fix it before things come to that point. Thanks!

[shawnbo42]

If you're handy with monitor boards, pull the board out, check the blue input on the connector. Should be on the edge of the monitor board somewhere. You should have a red, green, blue, black, and probrbly white wires on the connector. That's your color input from the game. Chances are you may have a bad solder joint at the blue pin, although ususally it's the red. Re-solder all the pins, just because you're there. Next thing I'd check would be the transistors on the neck board (the little board that plugs in to the back of the tube). There are three circuits there, identical. One is for red, one green, and one blue. Follow the adjustment pots traces' and you'll find the transistor. Swap it with one of the other two and see if the problem follows (as in now you have green instead of blue, etc). If it does, change the transistor. If none of this helps, you may have a bad color gun in the tube itself. You could try to rejuvenate the tube (if you have access to a machine). Or you could put in a new monitor, which, iirc, 19" tubes are not real expensive. But most likely, you'll find that one of those two things is your culprit. Usually when the tube goes, it'll be blue all the time. Good luck with it!

[InsaneDavid]

Late to post but thanks for the information! I'm starting to lean toward it simply being a bad line on the JAMMA harness. What backed it up in my mind was last week when I was replacing the microswitches on the control panel. The harness leads felt very brittle and cruddy. I also get intermittent continuity on a couple of the leads that run to the monitor board, it's always there but a test current varies in strength based upon moving the wires around. So I'm going to replace the JAMMA harness and see what happens. If anything I think it needs to be replaced anyway and is no big deal to do.

Anyone know how long JammaBoards.com has been out of them? I usually order parts from there but haven't in awhile and it seems they're out of stock. I'm also going to order a JAMMA extender so I can mount the Tetris board on the other side of the cabinet and be able to do the swap through the coin door.

[channelmaniac]

Dunno... I order mine from twistedquarter.com.

RJ

[Peale]

If the screen control on the flyback is turned up too high it can produce symptoms similar to what you're describing.

Unless it's /totally/ blue. Then that sounds like either a shorted color drive transistor or a heather to cathode short.

[InsaneDavid]

If the screen control on the flyback is turned up too high it can produce symptoms similar to what you're describing.

Unless it's /totally/ blue. Then that sounds like either a shorted color drive transistor or a heather to cathode short.

No, it no longer goes totally blue. It's more of a blue flicker anywhere there's black - namely the backgrounds of Klax or the title screen. I'm not going to do any further work on it for at least three weeks due to other stuff coming up.