Galaga Constantly Makes Credit Sound

Recently, my Galaga will make the insert credit sound after the machine has been on for a few minutes. It constantly makes the sound even though the game is functioning properly. Any ideas?

Thanks in advance!

There's a custom chip 07xx at position 4D on the board. You probably need to (VERY CAREFULLY) clean the legs on that chip & reinsert it.

Be careful cleaning them as those pins are VERY fragile on those cheezy custom chips.

RJ

Is it an original or a Gallag board set ??.
Got this from Mike Coates site.
http://www.arcades.plus.com/repair.htm


Occasionally would start game, but with credit noise continually playing and credits rapidly counting upwards. This is caused by CPU 4 (E5) not running properly. checked the eprom and ram (C5,D5 and E5) and ram was faulty. replace ram chip solved the problem.