Pac-Man random reboot

[videodan]

I was playing a game of Donkey Kong, and looked over my Pac-Man right next to it just as I cleared the Rivet board. Suddenly, it started to reboot on its own! Would anyone know what causes this to happen?

Thanks for any info and pointers.

 

[Arcadedoc524]

could be bad sockets under the program roms, or the cpu...
also seen bad ls 161's in the sync circuit cause the random reboot

 

[VidyaGamez]

Sounds like a power issue, i would check the condition on the edge connector, the fuse block and the edge pins on the pcb

 

[blown23t]

First step i would check your voltages/power supply..

 

[splattergatz]

think your wiring harness could be hanging funny and putting some twist onto the connector where it meets the game board. inspect inside the connector and look at the pins inside there. are they all looking the same ? is the spacing there all the same ? looking for any weak pins or crimped a little bit ? those wires can weigh enough that over time, the torque on the connector can cause all kinds problems there. once i could move the wire harness ever so slightly and cause a reset.
probably what your problem is the fuse holders down there in the bottom of the cabinet can get weak over time and not grip the fuse tight enough for proper electron flow. fuse holder(s) and fuse(s) should be replaced as its fun to cross out problematic possibilites off the list good luck

 

[videodan]

Thanks, guys! I'll pull it away from the wall, and open it up to see what may be causing the finicky behavior. It's probably nothing big.

 

[mecha]

I second the replacement of the fuse holders. the game board actually receives AC voltage in at the edge connector and rectifies it to DC for the components. if the fuse holders are corroded or otherwise junk, it will create a bottleneck and you will not only have a drop in voltage, but it will progressively burn the edge connector and contacts too. (the voltage drop is a manifestation of increased resistance!)

I would guess your voltage would have to be below 4.75V to the chips before it starts acting weird. you can learn how to test voltage at chips with my power supply guide: http://www.arcaderepair.net/the-essential-psu-guide/

it could also be caused by one of the row 6 roms (the 4 roms in a row below the Z80 buss board), 6H I think is one I had problems with in the past at my old job, I wound up installing a new socket on the board. also worth noting the original Pac-Man roms I'm going to assume came from Namco in Japan because the legs often corrode like Japanese chips of the era do. they'll have like a black tarnish to them. I clean these with my Dremel and a wire brush. if they've been exposed to those elements for too long it can make the legs brittle and break off too though... the wire brush gimmick can stress test that; if they're on the verge of breaking they'll break off then... not like a surprise later.