I will give it a shot.......

1) Bad connector.....clean the edge connectors with a fibrepen or something like that. Doesn't hurt to do this for all the boards after all those years.

2) Low 5V causing the soundboard to reset from time to time.....adjust the +5V with the little potmeter at the +5V powersupply. (Often these potmeters are bad, replace it with a new one or fixed resisitors)

3) The ROM's at the soundboard are dying.

All the pins from the top connector at the 5V power supply deliver +5V.

Ground is present at the right 2 pins (white wire) from the lower connector at the +5V power supply.

Marco

A1 J5 controls the cabinet switches....(slam -disable at your CPU board, often troublesome-, the coin switches, startbutton, etc.), it doesn't affect the behaviour of your soundboard unless the slamswitch kicks in...but then the CPU and soundboards will be reset completely. Sometimes these A1J5 and A1 J6 connectors are affected by a leaking battery at the CPU board, this can be easily seen when you look inside these connectors.

If you are still experiencing problems the ROM's *might* be the culprit.....

Resoldering the header pins is a good advce, cracked solder joints are pretty comon there. If not already mentionend, also tighten the screws at the LM338K regulator, they can become loose over the years.

Marco

Regarding the ground updates.....i never understood why people are using the +5V powersupply heatsink from all system80 games as a central point for all the ground connections. The transistor/regulator on it has the incoming 12V at its case and is isolated from the heatsink by just a tiny piece of material. Often this piece of material is damaged after dismantling the powersupply, 12V enters the the heatsink and -because the heatsink is connected to ground because of the update- a fuse blows. Seen this a few times already. Use a different point to join all grounds such as the lower lamp panel hinge in early system80 games, a screw left below in the backbox or one of the yellow straps in later games. And....with all respect......some of these updates are so poorly performed that it causes more problems than it solves......

Agree with you Steve. What I am trying to say...

1) Ground mod is a good thing to do, I perform it in all of my/our system80 and system80a games. In system80B I am more selective, in later 80B games I never do Ground Mod's and in the earlier ones I sometimes replace the 0.093 connectors at the transformer assy. I always double up the +5V and GND connection in the interconnect between CPU board and driverboard.

2) Trying not to be arrogant....only do modifications if you are able to do them or otherwise let a professional do it. I guess I repaired to many dodgy repairs at games and circuitboards already....

3) To my opinion using the heatsink of the +5V powersupply as a central point for Grounding is wrong. It is introducing a new potential problem as described above.

Marco