Fixing a Blurry Arcade Cabinet Monitor (CRT)

I recently acquired a Simpsons Bowling arcade cabinet that had a blurry, unfocussed display. Here’s how I fixed it (for free) to be good as new.

The Cabinet:

Front view - Overall, it wasn't in that bad shape.
Front view – Overall, it wasn’t in that bad shape.
Side-view of the cabinet.
Side-view of the cabinet.
I learned later on that this cabinet had been left outside, unprotected for several weeks before I picked it up. That would explain the water damage!
I learned later on that this cabinet had been left outside, unprotected for several weeks before I picked it up. That would explain the water damage!

Before:

IMG-20121004-01162
Gameplay
IMG-20121005-01175
Close-up of Blurriness
IMG-20121005-01174
Another Close-up

After:

DSC02499
That’s better!
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It helps when you can actually SEE the bowling ball.
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Made it to the Top 10 on my first try after fixing it. Coincidence? I think not!


The Fix (Step-by-Step):

Sorry about the awful picture.
Sorry about the awful picture.
  1. Find a friend.
  2. Power up the game.
  3. Open up the cabinet.
  4. Find the knob labelled “focus”. It should be on the flyback transformer, on the display board somewhere near the end of the picture tube. I’ve circled/boxed the flyback on my cabinet in the image above. ***DANGER – BE VERY CAREFUL WHEN WORKING NEAR THE PICTURE TUBE, ESPECIALLY WHEN IT’S POWERED ON! DO NOT TOUCH THE DISPLAY BOARD OR THE CAPACITORS! THE CAPACITORS ON THE DISPLAY BOARD ARE CHARGED WITH EXTREMELY HIGH VOLTAGES THAT CAN KILL YOU, EVEN WHEN THE MONITOR IS POWERED OFF. IF YOU ARE NOT COMFORTABLE WORKING WITH HIGH VOLTAGES, EITHER FIND SOMEONE WHO IS OR DO NOT ATTEMPT THIS FIX.***
  5. Have your friend watch the screen and tell you when the screen becomes focussed as you slowly twist the focus knob. The screen should become either clearer or more blurry. If it becomes more blurry, try twisting the knob the other way. If that doesn’t work, you’ll probably need to replace the caps on the display board.

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