I had an opportunity to buy an inexpensive Galaga locally.
The owner told me that it started up and displayed the attract mode, but none of the controls worked and there was no sound.
He also told me that someone had worked on the game for him and had installed a switcher.
The cabinet, control panel, marquee and bezel all looked very good. The cabinet almost looks too good. It's very possible that the cabinet has been painted and new artwork applied. There are some scuffs and scratches on the artwork, but overall it looks much better than any cabinet that I've seen that has been in the wild. It is missing the artwork on the kick panel. I buy games to play, so if the graphics are reproductions, I'm not gonna worry too much about it.
The price was very good, so I paid for it and took it home.
I checked the control panel harness and grounds and powered it up. Sure enough, the controls had no effect.
I powered it back down and started checking online for possible solutions. I ran across multiple results that said the card edge connector could be connected backward. The thought that this could happen and the game board wouldn't fry was surprising. I printed the pin-outs and started comparing. Sure enough, the card edge connector was on backwards.
Interestingly, Galaga has separate power and video connectors independent of the card edge connector.
I powered it back up and the controls worked, except for the fire button.
Next I checked the audio amplifier. It was visibly damaged, obviously from letting the magic smoke escape (see the attachment). I checked the game schematics and the specs on the MB3730 audio amp. It requires +12VDC. I checked the cabling and found that the person who installed the switcher connected the +12V line from the board to the switcher's -5VDC output!!
I desoldered the amplifier (see the attachment), and temporarily connected a small battery powered audio amp to the pads for pin 1 (IN) and pin 4 (GND). I powered up the game and heard the diagnostic "boom". I coined it up and the sounds were there, albeit very low volume from the small amp and speaker.
Knowing that the damage was (most likely) confined to the amplifier, I ordered a replacement from Twisty (thanks!).
The audio amp chip came yesterday and I soldered it onto the board. Sound, glorious sound!
With everything else working, I went back to the fire button. I checked the button with an ohm meter. The button was fine.
Next, I traced the wires back to the "rapid fire board". I tried moving the connector to each position with no luck.
Again referring to the pinouts, I directly tied the fire button wires to the edge connector pin "M" and ground.
The game plays like a charm using this temporary fix.
I'll need to figure out if the issue is the connector on the rapid fire board, or someone on the board itself. But for now, the game is quite playable.
The owner told me that it started up and displayed the attract mode, but none of the controls worked and there was no sound.
He also told me that someone had worked on the game for him and had installed a switcher.
The cabinet, control panel, marquee and bezel all looked very good. The cabinet almost looks too good. It's very possible that the cabinet has been painted and new artwork applied. There are some scuffs and scratches on the artwork, but overall it looks much better than any cabinet that I've seen that has been in the wild. It is missing the artwork on the kick panel. I buy games to play, so if the graphics are reproductions, I'm not gonna worry too much about it.
The price was very good, so I paid for it and took it home.
I checked the control panel harness and grounds and powered it up. Sure enough, the controls had no effect.
I powered it back down and started checking online for possible solutions. I ran across multiple results that said the card edge connector could be connected backward. The thought that this could happen and the game board wouldn't fry was surprising. I printed the pin-outs and started comparing. Sure enough, the card edge connector was on backwards.
Interestingly, Galaga has separate power and video connectors independent of the card edge connector.
I powered it back up and the controls worked, except for the fire button.
Next I checked the audio amplifier. It was visibly damaged, obviously from letting the magic smoke escape (see the attachment). I checked the game schematics and the specs on the MB3730 audio amp. It requires +12VDC. I checked the cabling and found that the person who installed the switcher connected the +12V line from the board to the switcher's -5VDC output!!
I desoldered the amplifier (see the attachment), and temporarily connected a small battery powered audio amp to the pads for pin 1 (IN) and pin 4 (GND). I powered up the game and heard the diagnostic "boom". I coined it up and the sounds were there, albeit very low volume from the small amp and speaker.
Knowing that the damage was (most likely) confined to the amplifier, I ordered a replacement from Twisty (thanks!).
The audio amp chip came yesterday and I soldered it onto the board. Sound, glorious sound!
With everything else working, I went back to the fire button. I checked the button with an ohm meter. The button was fine.
Next, I traced the wires back to the "rapid fire board". I tried moving the connector to each position with no luck.
Again referring to the pinouts, I directly tied the fire button wires to the edge connector pin "M" and ground.
The game plays like a charm using this temporary fix.
I'll need to figure out if the issue is the connector on the rapid fire board, or someone on the board itself. But for now, the game is quite playable.