Galaga Issue

FlavaDave

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I have an original Galaga machine which I am having a few pcb issues with. First off, it works and plays fine, but it has a few glitches. Here are some of the symptoms.

1. I have all sounds, EXCEPT for the explosion sound. That is the only sound missing.
2. The speaker hums pretty bad, and noticed the MB audio amp has been replaced before.
3. Later on in the gameplay, the "Ready" text will appear before you shoot all the aliens. Sometimes it appears at random.
4. Sometimes the it will go to "Game Over" for no apparent reason.
5. When your ship is captured, I shoot the bad guy, but it does not give me my double ship.

So far I have replaced the main caps, cleaned all the chip legs, cleaned the sockets, and looked for broken traces. Checked the original PS voltage from the board and it's kinda high, but I have another Galaga cab with a switcher, and get the same issues. Any help would be appreciated.
 
The explosion sound is generated by the 54xx chip on the cpu board, that is it's only function, the hum in the speaker should be either a noisy 12V supply or one of the caps in the audio amp ckt, the other random problems could be a bad resistor pack, they are famous for problems, if you take the ribbon cable off you should be able to read from +5V to each leg of the resistor packs (the larger one on both boards), if any read over 2.2k the resistor pack is bad, some will read lower because of other components in parallel but none should read higher.
Dick
 
Galaga is a notoriously crappily built game.

They use cheap sockets that go intermittent over time. They also have a couple of different types of resistor packs they've used. If the ones you have are about 1/4" tall and flat then those are the kinds that give a huge amount of problems.

The Augat sockets only make contact with the chips on the insides of the legs. If you clean the custom chips you MUST make sure to clean the insides of the legs too!

The TI sockets only make contact with the chips on the SIDES of the legs! YES, the narrow sides! These are surfaces that don't get cleaned when you use various methods such as fiberglass pencils, dremels with wire bruses, erasers, etc...

Any Galaga board that crosses my bench gets ALL of the 24/28/40/42 pin sockets replaced with good double wipe sockets AND all of those flat resistor packs replaced. Once that's done and the custom chips are cleaned/inserted then the board can actually be considered reliable enough to troubleshoot for other issues such as bad CPUs or other IC issues.

RJ
 
Are you waiting for the ship to take a dive before you shoot it? If its not diving I dont think you get double ship, only points for your ship you loose.
 
Re:

It doesn't matter if it dives or not. I will shoot the bad guy and my ship dives and attacks me even with the bad guy gone, like the bad guy is still there or like I really didn't kill him.
 
I've never had any issues with those sockets unless they were physically damaged (corroded or took a smack when piled with other boards)...

RJ
 
Re:

Thanks for the replies, I am going to start replacing the resistor packs soon, hopefully that will cure something.
 
It doesn't matter if it dives or not. I will shoot the bad guy and my ship dives and attacks me even with the bad guy gone, like the bad guy is still there or like I really didn't kill him.

That's not a glitch in your game... it's just part of the gameplay. When your ship is captured, you have to wait until the bad guy is in motion with your ship before you try to shoot him. If you shoot the bad guy while he's just sitting at the top, your captured ship will turn red and attack you. You can either shoot it for a small amount of points OR (a better suggestion) refrain from shooting it. If you don't shoot it, it will come out again with the rest of the ships in the next round.
 
Re:

Hmmm, that makes sense. What about the "Ready" text showing up at random, and then sometimes it goes to game over for no reason?
 
Hmmm, that makes sense. What about the "Ready" text showing up at random, and then sometimes it goes to game over for no reason?

I'm not sure about those, but someone here once mentioned that they had a Galaga that was hacked. It would only allow you to play up to a certain amount of points before the game would automatically end. Apparently the owner didn't want people playing all day on one quarter. Maybe it's hacked...? (Maybe not, but thought I'd throw it out there.)
 
Re:

It's not hacked to my knowledge, it does have rapid fire enabled. It game overs sometimes within the first few levels. Expecially when I double up my ships, when it decides to let me shoot them and earn it back that is:\
 
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