Gottlieb system 1 help

[Mxzmark]

Looking for some advice on a problem I'm having with a few of my system 1 games, a buck Rogers and a Sinbad. Here is the issue. After playing 15-20 straight games I sometimes loose all the sound (still scores but no sound when any switch is hit). The games will still play the start up tunes and game over tunes but that's it. Turning the game off then back on doesn't fix it. Leaving the games off for 20 min seems to fix the issue. To me it seems like heat may be the issue. Since buck Rogers uses a sound board and Sinbad uses a chime unit I'm thinking the issue is the game prom getting hot on the cpu and causing this strange behaviour. I have read that on some of these games they can get hot and mine seem to be quite warm when I checked them. Has anyone else seen this problem in their travels? Would gluing a heat sink onto the proms fix it? Btw both games have been totally rebuilt, all connectors re-pinned, all ground mods done and running the original CPUs with no corrosion on them.

 

[Menace]

You could always pickup a can of freeze spray and hit any of the suspected chips that are hot and see if the sound comes back.

D

 

[sylvain]

Good advice from Menace above.
Basically, troubleshooting will need to pinpoint where the issue actually is.
Freeze spray can help locate the bad component or solder joint.

Most probably a bad chip or socket/solder joint temperature-sensitive on one of:
- MPU Solenoid Drive circuits (some are for the sounds);
- MPU-Driver harness (unlikely)
- Driver board (there are 4 drive transistors for the sound triggers)
- Sound board: input decoder
- Sound board PROM (also running hot)

Good luck!
- Sylvain.