Older monitor has green tint and lines after turn on

john2654

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Older monitor has green tint and lines after turn on

I have a monitor on a Caveman Ninja arcade that turns on fine and then a couple seconds turns into the picture shown. I'm guessing a capkit?
 

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Always a good start, and given the age/price always worth doing even if that isn't it. Not that I have any significant experience, but those raster lines make me wonder about the screen pot.
 
A cap kit doesn't solve all problems, but faulty caps can cause a wide variety of image problems. It's always best to start there. I got a monitor a month or two ago, that had a lot green like that. I could look closely and still see red and blue, but there wasn't any white. Turns out, it was actually my picture tube.
 
I'm sure it defintely needs a cap kit. If you have access to a rejuvenator you'll want to test the tube.
 
A picture like that can definitely be caused by a faulty tube. Other things that can cause it include a shorted video output transistor on the neckboard, a bad neckboard pot, or any number if misadjustments. You don't mention what kind of monitor it is, but generally, I'd start by replacing caps and resoldering bad joints, etc. Does the picture look OK at first, then instantly flick to green, or does it look dim then gradually get brighter and turn to this? The latter can also be a bad flyback. If it's a k7000 with a flyback with white knobs - replace it!

-Ian
 
It could also be that the 'green' signal coming from the game PCB has a bad connection. Try just re-seating the connectors between the monitor and game board first.
 
A picture like that can definitely be caused by a faulty tube. Other things that can cause it include a shorted video output transistor on the neckboard, a bad neckboard pot, or any number if misadjustments. You don't mention what kind of monitor it is, but generally, I'd start by replacing caps and resoldering bad joints, etc. Does the picture look OK at first, then instantly flick to green, or does it look dim then gradually get brighter and turn to this? The latter can also be a bad flyback. If it's a k7000 with a flyback with white knobs - replace it!

-Ian

Yes, the monitor is perfect when first turned on. Then after a couple seconds, it goes to this green/ line state. Before it had a single white line that ran left to right and fixing a cold solder joint fixed it. It's been fine for a couple months, now this. I'll give it a new cap kit and check for cold solder joints. Thanks
 
Sorry, finally got to pick up the monitor today. Looks like its a Wells Gardner 19K4625
 

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I'd say either it's a tube short or a color drive transistor failing.

You could swap color drive transistors and see if the problem moves to a different color.
You could test and clean the tube if you had a rejuvinator handy.
Might check the color adjustment pots and see if wiggling the green ones makes the color jumpy, etc.
And yes, that's a K4600.
 
In my experience, if it's got retrace lines like that it's probably the tube shorting out... which you may be able to fix with a rejuvenator, or if you're feeling like MacGyver today, just take a screwdriver and lightly tap on the side of the tube neck and see if you knock the dirt off the gun.

If it doesn't fix it, knock a little louder :) You'll either fix it or destroy it.

Usually if it's the driver transistor, it won't have retrace lines, it'll just be really really green.
 
Did a capkit and reflowed a bunch of cold solder joints. Powered it on and it did the same green wavy screen. Knocked around on the tube neck and it now works fine. Been working fine for a couple hours now. Must've had dirt on the gun, thanks! But since I did the cap kit, it now even looks much better. So a win win.
 
Just a follow up...I returned the monitor to the owner yesterday and received a nice $20 bill for the repair job. Definitely not worth my time + parts, but nice to see the Joe & Mac working again.
 
Just a follow up...I returned the monitor to the owner yesterday and received a nice $20 bill for the repair job. Definitely not worth my time + parts, but nice to see the Joe & Mac working again.

Twenty bucks? Cripes man, that's cheap. Can I send you some stuff?

:cool:
 
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