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Purple screen
Question from Joel: I just found a Ms.Pacman/Galaga 20th Anniversary full size machine sitting on the side of the road. After watching several of your videos it appears to have everything except both coin mechanisms. The cabinet is solid and all the wiring appears to be in excellent shape. Some of the spade connectors attached to the buttons are slightly rusted but don’t appear to be in need of replacing. This is my first attempt at anything electronic so I am over thinking everything. Plus, I am a tight wad do-it-yourselfer that has difficulty asking for help. It has power because the screen is purple and I can barely read the words game over. By touching a jumper wire to the back of the monitor raster thingy I am able to display blue red and green. I am unable to display the 3rd primary color of yellow however, I think I have yellow because I can display green which cannot happen without yellow and blue. Please correct me if I am wrong. I have no sound, but that may be because it is stuck between games. Anyway, followed your instructions on discharging a tube which I have done several times and only once have I seen a small spark. At this point I am not comfortable with taking out the computer board to get a better look at the capacitors and what ever else it has. Do you have any idea why I only have a purple screen and what I should do about it. I think it might be associated with the fly back gizmo but I really have no idea. I would like to keep it as close to original as possible but will have no problem upgrading to a flatscreen. Thanks in advance for any advice. Joel
1 answer
Response from Jonathan: Joel,
It actually sounds like it might be a power supply or board issue. Your monitor is probably working if you are getting the colors when you touch the jumper wire to the neckboard (BTW, yellow should not comes up as most monitors only have red, green and blue guns). Of course, even though your monitor is getting power it doesn’t mean that your board is getting power. Both of these systems run off of different voltage types. Your board runs off of DC power (usually generated from a switching power supply) while your monitor and most of the lighting in your cabinet runs off of AC power (sometimes through a transformer but it’s still AC).
You need to make sure that your switching power supply is working correctly. Check out our post on Checking And Replacing A Power Supply for more information. If you are sure that you’re getting the correct voltage to the board then you might have a board issue and we can help you troubleshoot it further from there.
Hope that helps. Thank you for your question and good luck with your repair.
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