Hi everyone
Having some switch matrix issues, hopefully someone can offer some input regarding troubleshooting.
I have a Demolition Man MPU from a friend which was severely affected by battery corrosion. He opted to buy a Rottendog MPU to replace it. I transferred the ASIC, processor and game ROM to the new MPU and have it in my own Demolition Man for testing. I am now having problems with the claw, which will appear to work normally before stopping and getting stuck at random points when moving left to right.
I figured out that it was stopping because the claw left (and sometimes the claw right) switches (switch 25 and 26, both opto switches) were sometimes registering while the claw was in the middle of moving from left to right or vice versa. Of course once one of these switches triggers, claw movement stops. The claw usually gets stuck at that point, and when I go into test mode, moving the claw will trigger the claw left or claw right optos as soon as I try to get it to move, making it stop again.
I have narrowed this issue down to the Rottendog MPU. The claw optos work perfectly with my original WPC MPU board in the game. I have also tried the following:
- Replaced U20
- Replaced game ROM
- Replaced ASIC
- Reflowed solder J207 and J209
- Reflowed solder on U20 socket
- Reflowed solder on U19
- Verified continuity from the column 2 and row 5 and 6 connectors to U14 and U13 respectively
- Verified 12v is present at U20 pin 10
- Verified resistors and diodes associated with column 2 and rows 5 and 6 test within spec
Not really sure where to go from here. I don't think it is a connector issue as other switches in these rows and columns work fine. I don't think it is an opto board issue as all other optos work fine. I don't think it is a power issue as other switches and 12v loads work fine.
Any help is appreciated!