Qbert Monitor Woes

rockymtn

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Bismarck, North Dakota
I have a Qbert with an original dedicated PCB and original WG4900 monitor in it that has the screen issues pictured in the attachments.

Here's what I've done so far:
1)Recapped the monitor and reflowed all the cold solder joints on the monitor board
2)Reflowed solder on filter board connectors(twice) and checked the trace continuity (no broken traces)
3)Installed a rebuilt power supply (Thanks Riptor)
4)Cleaned socketed chips and edge connector on the main PCB

When voltage is checked on R503 I get 150VDC. I'm supposed to have 130VDC I believe on that resistor. Is this a voltage regulator issue?

Thanks for the help.
 
Last edited:
Are you sure your plugging in the video connector correctly? I've seen something similar before when I had the connector backwards.
 
I'll try to send pictures of the monitor board in the next day or two. The issue there is that everything is inside a custom cocktail cabinet and I have to pull the monitor tube completely out to have good access to the monitor board and I'm watching the kids by myself this weekend ;)

I did however label the top of the video connector with a Sharpie so I'd know which side was up as I was removing the monitor from the cabinet, so it should be oriented correctly. Just to be sure...there's the set of six pins and then an additional set of three pins where the video plug goes into the monitor board and I have the connector (which has six wires going into it) plugged into the bottom six with my "T" showing on the top side.
 
You say you are have this in a "custom cocktail". Do you have an isolation transformer in it? Is it outputting the proper voltage?
 
Yes, I've got all the original "guts" including the large power block transformer still in place in the custom built cocktail. I measured the voltage going into the monitor board and I got 125V, so that should be right on.
 
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