Midway Games

[channelmaniac]

Model: Space Invaders
Symptom: No sound

Board arrived dead. Replaced bad RAM at H6 and tested. Board had some sounds, but not all. Replaced the LM3900 chips at M4 and P4 to restore the Missile sound. Replaced LM3900 at K3-4 to restore the explosion sound. Replaced the LM3900 chips at K4 and K5 to restore the invader hit sound. Tested.

[channelmaniac]

Model: Galaga
Symptom: Dead. Garbage on screen

Replaced all the 24/28/40/42 pin sockets. Resistor packs were of the OK type. Tested. Replaced bad RAM at 1K on the video PCB. Tested.

[channelmaniac]

Model: Galaga
Symptom: Missing parts. Rebuild.

Board had attempted repair damage.

Replaced all the 24/28/40/42 pin sockets. Replaced 3 resistor packs that were made of individual resistors. Removed all 8 2147 RAM chips and replaced them with 2 2148 RAMs. Tested. Board would boot and play but had no sprites, just empty boxes on the screen. PROM at 1C had no outputs. Worked backwards in the circuit to the LS377 @ 2D. Clock was making it to pin 11's solder pad, but not to the top of the leg. The leg had been cut and not fully soldered back together by a previous tech. Removed the IC, installed a socket, and installed a replacement LS377. Tested.

[channelmaniac]

Model: Galaga
Symptom: White screen

Replaced all the 24/28/40/42 pin single wipe sockets and unencapsulated resistor packs. Tested. Replaced 2 bad Z80 CPUs. Tested.

[channelmaniac]

Model: Galaga
Symptom: Random RAM errors

Replaced all the 24/28/40/42 pin single wipe sockets and unencapsulated resistor packs. Tested.

[channelmaniac]

Model: Galaga
Symptom: Striped sprites with color issues

Removed the 8x 2147 Fast RAM from the board. One tested bad. Installed 2x 2148 chips as this customer puts thousands of hours on his games and these will pull less power and run cooler. Tested.

[channelmaniac]

Model: Ultimate Mortal Kombat III
Symptom: Missing colors on output. No sound.

Board suffered shipping damage causing these issues.

Replaced cracked 74ALS541 chip in the video output section. Replaced cracked 470 ohm isolated resistor pack. Tested. Sound cable was plugged in backwards on the sound PCB. Plugged cable in correctly and the sound fully returned. Tested. DIP switches were not working. Replaced both banks of switches and tested. Cleaned edge connector pin for Player 1 Button 3 and retested.

[channelmaniac]

Model: Ms Pac Man
Symptom: Dead

Repaired damaged edge connector. CPU was missing clock and Sync Bus Controller was loose in socket. Replaced CPU socket, Sync Bus Controller socket, and sacrificial socket on Controller. Zip tied module into place properly and tested.