Anti Aircraft/ XM-501 Vertical(?) Collapse

Phetishboy

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So I've had this game about 10 years. Within the first month of owning it, I recapped the monitor. For the first 2 or 3 it worked perfectly. Then I one day I was met with a blank screen which I was able to somehow get working again. Worked for another few years, but about 5 years ago, the kids turned the machine on and got a bright horizontal line across the center of the screen. You could still see everything moving within that horizontal horizon line, but obviously there was collapse. Since this monitor is mounted horizontally and the line is horizontal, I'm assuming that means it's a vertical collapse? Seems like every time I take a guess I'm wrong. Here's some pictures of the chassis to help identify it and identify what I need to replace. Thanks.

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So I did a little searching and found that I'd asked this question someone else's thread earlier this year, which is probably why I couldn't find it. Here are some excerpts from that thread:

cwilksen said:
First check the yoke for continuity between black and green wires. Do this with the power off.
I can't remember if they're soldered or if they use a connector. (connector I think)
Unplug the connector and check the wires coming from T3 on the chassis.
With the yoke disconnected from T3 it should measure about 30 ohms and T3 should be about 10 ohms.

Measure the DC voltage from Q13-collector to ground. (power on obviously)
You can find it on pin 25 of the plugin chassis board. Should be about 68 VDC.

Check the vertical size pot R65 is working and that R64 is ok. Do this with the power off.
Measure the resistance from Q13-emitter to ground. You should be able to vary it from 10-25 ohms by gently turning the pot.

omherone said:
Check R81 if open or
Just jump it. Or just twist the legs together.

If I was going to need to add caps to board
Most can be replace without moving the board
But if I did it can be pushed up from the bottom
After desolder the grounds from bd to chassis ground and remove zip ties on pins.

Definitely need to detox the wire wound pots
Common issues I had since it came out. Lol
I would use circuit cleaner to clean up the chassis not wash it at all
Need to check R81 first.
Before replacing the large multi section can
New caps should be replaced to restore the chassis for sure.
 
Oh, and I went and found a YouTube video on someone fixing one of these things. I don't know who the guy is, maybe he's on here, maybe he isn't. He just talks to himself and repeats himself a lot and never really gives detailed/accurate data. He ended up replacing the vertical output transistor on his 501 twice, but never really says what value it's supposed to be, just that the first replacement was overdriving it, and the second one was under driving it. He was basically just taking random transistors out of his parts bin and putting them on the frame. He's also not sure exactly what resistors are supposed to be replaced, just that they probably need replacing. He talks about R64 a couple times, but never mentions R81.
 
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John McCann in Altura, MN. I sold him an Anti-aircraft game many years ago. As I remember I had similar problems when I first acquired the game. Sorry, can't remember what I did to fix it. I'm sure I caped it and I also think I replaced the the trans. in the out put stage, not sure if that actually fixed it.? Not even sure anymore if it was Horz or Vert collapse. Good luck with the old beast.
 
John McCann in Altura, MN. I sold him an Anti-aircraft game many years ago. As I remember I had similar problems when I first acquired the game. Sorry, can't remember what I did to fix it. I'm sure I caped it and I also think I replaced the the trans. in the out put stage, not sure if that actually fixed it.? Not even sure anymore if it was Horz or Vert collapse. Good luck with the old beast.
Oh Johnny boy, no I did get his asteroids cabaret back in 2017, but this one was from Freedom Wisconsin. Oh well, sounds like the issue might be a common thing.
 
So back to my issue, I took a few pictures of the transistors on this chassis frame. Just gotta remember which one is the VOT.

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