G05 monitor is dimming in the middle.

BrokenTrace

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Now that I got the game running, the monitor needs to tweak.

The G05 is starting to fade in the middle now after the game is on for 15 min or so. It looks like the vectors are dimmer in the middle, a foggy area of around 4" in diameter if you could measure it. The vectors on the rest of the screen are fine. If you turn the game off for awhile then turn it back on the screen will be fine again but then fade out.

The monitor had a cap kit and some other repairs back in 2002. Any help on what's going on? Thanks!
 
Does the screen image get bigger and bigger (blooming) as it dims? I had that problem with the dimming before and it was the HV diode. Arcadeshop has them.
 
It does not on this one. But if I put in a different pcb boardset, the screen does that (the screen gets bigger and smaller. almost like breathing). I thoght it was the pcb and was going to save that one for a different post. No, on this one, the image is the same size and the middle of the screen starts to fade out and is less bright in the middle, like a foggy middle section of the screen.
 
It does not on this one. But if I put in a different pcb boardset, the screen does that (the screen gets bigger and smaller. almost like breathing). I thoght it was the pcb and was going to save that one for a different post. No, on this one, the image is the same size and the middle of the screen starts to fade out and is less bright in the middle, like a foggy middle section of the screen.

First place I would start is check the HV. Also if your focus voltage is drifting it would cause the problem you describe. So at this point, what you need to do is check your voltages (or better yet, hook the probes up so you can leave the meter hooked up and see if your voltages start to drift as your picture starts to lose focus.

It would be best if you had a HV probe, but you should be able to check just about everything with just a multimeter.

Good luck,
mickey
 
hmmm, some oddball blanking problem with your gameboard?.. dunno.. never seen that before on a g05 could be a rare chassis problem.
 
Thanks for all your replies everybody. Turns out it was the HV diode...or actually, the connection at the HV diode. I was taking the diode out when I saw all the rust inside the connection. So I took a small tap to it and replaced the spring and cleaned all the corroded wires. It's been running now for about 30 minutes and is still looking good with no fade.

So I was going to swap the HV diode with one I had in another unit when I saw the rust and the obvious problem, but the diode in the other unit was the same except the number H1802 and H1806, other than that, they were identical. So my question is, could I still use the replacement diode in the unit or should I make sure it's an exact replacement?

Thanks!
 
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