Why is Galaga giving 2 credits for one quarter

Wiz

Well-known member
Joined
Feb 4, 2010
Messages
1,245
Reaction score
43
Location
Ann Arbor, Michigan
Hello,

My Galaga machine keeps giving 2 credits for one quarter on both coin slots and I am not sure why. It is not in the dips as I have put another board in (cab was converted to Jamma before I got it) and any other board also experiences the same. I have also done all the possible combinations on the galaga dips without being able to get it down to one coin = one credit. The mechs and switches appeR to be functioning as they should but keep giving out 2 credits- first time I have seen this. Any ideas?
 
Last edited:
Is the dip switch set correctly?

Switch bank 6K sets the number of credits, lives and lives given at certain
scores:

SW1 SW2 SW3 (Coins per Credit)
--------------------------------------------
ON ON ON FREE PLAY
ON ON OFF 4 Coins 1 Credit
ON OFF ON 3 Coins 1 Credit
ON OFF OFF 2 Coins 1 Credit
OFF ON ON 2 Coins 3 Credits
OFF ON OFF 1 Coin 3 Credits
OFF OFF ON 1 Coin 2 Credits
OFF OFF OFF 1 Coin 1 Credit
 
Thanks, but yes, I did try the dip settings you have here and it did not affect it.

Is the dip switch set correctly?

Switch bank 6K sets the number of credits, lives and lives given at certain
scores:

SW1 SW2 SW3 (Coins per Credit)
--------------------------------------------
ON ON ON FREE PLAY
ON ON OFF 4 Coins 1 Credit
ON OFF ON 3 Coins 1 Credit
ON OFF OFF 2 Coins 1 Credit
OFF ON ON 2 Coins 3 Credits
OFF ON OFF 1 Coin 3 Credits
OFF OFF ON 1 Coin 2 Credits
OFF OFF OFF 1 Coin 1 Credit
 
Since he has the same problem with multiple boards, it probably isn't the dip switches.

This is the case- it is happening with multiple boards. Even if I just flick the coin switch I get two credits so it is not a situation where the coin is hanging and causing it. I have never heard of switches designed to do this as it is generally through the dips but not sure what is up- pretty bizarre.
 
Sounds like a wiring issue then. Can you narrow it down to one coin switch? Or, does it do the same with both switches? Any wires (besides ground) daisy chained to the coin switch?

Is the cabinet wired for Jamma and does the same problem on a Jamma game? If so, you can rule out the Galaga adapter.
 
Just spitballing here, but if the coin switch is wired backwards (ie wired to normally closed rather than normally open) maybe it's confusing the board every time a coin goes through?

Does the game have a service coin-up switch, and if so does it also give two credits each time you push it?
 
p1 coin and p2 coin must be tied together somewhere in the cab. One coin drop triggers a pulse on both coin inputs giving you two credits per coin.
 
Thanks for all the great ideas folks, I will dive back into the game this evening after work.

Sounds like a wiring issue then. Can you narrow it down to one coin switch? Or, does it do the same with both switches? Any wires (besides ground) daisy chained to the coin switch?

It happens with both switches. I don't think anything else is daisied but I will check.

Is the cabinet wired for Jamma and does the same problem on a Jamma game? If so, you can rule out the Galaga adapter.

Yes and yes. I bought it as galaga but it had been retired, yet running a galaga board with adapter. Other Jamma games do the same.

Just spitballing here, but if the coin switch is wired backwards (ie wired to normally closed rather than normally open) maybe it's confusing the board every time a coin goes through?

Does the game have a service coin-up switch, and if so does it also give two credits each time you push it?

Possible- I will be swapping some wires and switches this evening

p1 coin and p2 coin must be tied together somewhere in the cab. One coin drop triggers a pulse on both coin inputs giving you two credits per coin.

I'll take a look
 
Hello,

My Galaga machine keeps giving 2 credits for one quarter on both coin slots and I am not sure why. It is not in the dips as I have put another board in (cab was converted to Jamma before I got it) and any other board also experiences the same. I have also done all the possible combinations on the galaga dips without being able to get it down to one coin = one credit. The mechs and switches appeR to be functioning as they should but keep giving out 2 credits- first time I have seen this. Any ideas?
Did you ever get to the bottom of this? My Galaga is doing the exact same thing as your's. Thanks, Jay
 
Back
Top Bottom