Galaxian Don't Work

pmichelsen

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I bought a Galaxian a few years back and when I got it the monitor was dead and there was no life from the board. I was able to find a unknown condition board on ePay for 12 bucks so I figured what the hell. The board showed up and I plugged it in and it played blind. I was stoked but had no intention on getting the monitor fixed anytime soon so I tucked both boards away safe and sound.

Fast forward to the beginning of this year, Phetty boy started posting pictures of his Galaxian and made me jealous so I wanted to join in the fun. I had a brand new monitor for the Galaxian all boxed up so I built a new frame for the monitor and it fit safe and sound in the cabinet.

After I got the monitor in I pulled out the working board and plugged it in, and I hear is an annoying sound followed by a bleep, bleep, annoying sound, bleep, bleep, and on and on and on.

I decided to try the old board too and it is still lifeless. I have tried unplugging the CP, coin door, marquee, no change. I tried moving the test switch, no change. Voltages seem a little funky I believe they are supposed to be 12V and 5V, is it possible my transformer took a shit while it sat? I really hope this isn't the case because I just shipped my spare wiring harness and transformer assembly off to its new owner.

Anything I should rebuild or replace? I am aware that these are some of the most reliable boards outs there. If you fix these boards PM me your price, I would be willing to ship two complete boards in exchange for one working board....
 
What voltages are you seeing? Galaxian should take in AC input to the board and then convert it to DC. I'm not sure what the exact AC values are but you'd definitely be seeing AC input from the transformer and not a +5 or +12 DC reading. If you're checking the +5 it definitely has to be on the board and somewhere after the AC gets changed to DC. I just go across a 7400 series chip to check the +5 that way you can do that for any game basically.
 
INTERESTING! I was thinking that the voltages might be AC but I couldn't remember for sure. I will double check those readings and see what I come up with.
 
What voltages are you seeing? Galaxian should take in AC input to the board and then convert it to DC. I'm not sure what the exact AC values are but you'd definitely be seeing AC input from the transformer and not a +5 or +12 DC reading. If you're checking the +5 it definitely has to be on the board and somewhere after the AC gets changed to DC. I just go across a 7400 series chip to check the +5 that way you can do that for any game basically.

Alright I checked the voltage at a 7400 series and it seems to be low, around 2.5 - 3. Any advice on where I should head to from here?
 
one thing I found helped with my Galaxian boardset when the voltage was low was to replace the big 10000 uF capacitors on the board. Mine would play for a bit then reset randomly...replaced those caps and its good now.

Josh
 
Alright I checked the voltage at a 7400 series and it seems to be low, around 2.5 - 3. Any advice on where I should head to from here?

Check the 4 fuses in the bottom of the cab and the holders. If everything looks good there you might have a bad transistor...the one on the big heatsink. Replace with a tip31c. Usually when you have low voltage(around 2.5) its one of those two things.
How does the pcb edge connector look?
 
I will double check the fuses and check out the transistor, the edge connector looks good. Actually I just remembered that last time I messed with it I pulled all of the fuses out and metered them, all checked out fine. And the fuse holders are brand new, and I replaced all connectors going to the fuse holders. So I guess I will focus my attention on the resistor.
 
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