Pheonix - Toei CM-A20 - First time trying to repair arcade

ekgzo

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Hi All. I picked this arcade machine from a yard sale for $100 as a gamble. I always loved pheonix on the Atari, so was excited to bring this home. The machine powers on, the marque lights up, the game actually plays with sound, the buttons are all working and I can play the game blind (allegedly that's the right term?). However, the CRT is displaying garbled lines not reflective of the underlying game. I drilled out the lock on the back (tried to pick the lock but it was very gummed up) and screwed around with the various pots for focus, vertical, horizontal adjustments, and so on. The image on the screen does change (gets brighter, more or less focused), but nothing that resembled the actual game.

I've done some light console repairs, but have zero experience dealing with CRTs or arcades. I know enough to not touch the anode or CRT itself even after being unplugged, but that's about it.

Does this seem like a CRT issue? a board issue? a connection issue?

Looking for advise on to where to start troubleshooting.

Appreciate the help in advance.
 

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The first big knob on the left is Horizontal Hold, that's what is wrong with your image. If that knob doesn't fix it, there might be something wrong with the monitor or (less likely) something wrong with the horizontal sync generation on your board. I see it's combined sync (white wire) so it's possible H sync isn't getting mixed in.
 
The first big knob on the left is Horizontal Hold, that's what is wrong with your image. If that knob doesn't fix it, there might be something wrong with the monitor or (less likely) something wrong with the horizontal sync generation on your board. I see it's combined sync (white wire) so it's possible H sync isn't getting mixed in.
Thank you. I will try the horizontal hold again. From some other reading, I think this dial in the little silver box (see attached) is also some sort of horizontal adjustment? I have a can of CRC QD contact cleaner, will that work fine for cleaning the pots?

Screenshot 2025-11-17 at 11.07.27 AM.png
 
Update. I was able to fiddle with the V hold and H hold until the image stabilized in one place. I can make out the stars and backdrop that makes up the title screen of the game. Does this seem like toying around with the pots is still the right move? I feel like this is as close as I was able to get it with adjusting the pots. Is there something else to adjust with the CRT or on the CRT's board? Is the next step pulling the CRT board?
 

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You definitely have no horizontal sync there still, so you've either got a problem with the PCB or the monitor. My money is on the monitor.
 
You definitely have no horizontal sync there still, so you've either got a problem with the PCB or the monitor. My money is on the monitor.
Based on your comment I decided to adjust the horizontal oscillator L5 and was able to get the picture 10 times better. I can actually make out the game now (see attached). When I adjusting the horizontal oscillator, the changes don't feel very gradual, instead it feels like it quickly jumps in and out of sync. Not sure if this is typical, perhaps this dial needs to be cleaned so I can more effectively make minute changes? This whole thing is a learning experience and I feel like getting this kind of picture is very encouraging.
 

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Now that looks like horizontal sync is fine but vertical sync is not correct. Yes sync is supposed to snap-in, the monitor supports a small range that i needs to lock on to.
 
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