Road Riot 4WD Repair Logs
Symptom: No sound
Volume was set to zero. This model is strange in that you must go into the electronic setup and choose the volume setting. There is no volume control.
If the EEPROM used to store the settings is bad then this setting will not be saved. The sympom of this is if you set the volume and other settings and they aren't retained if the board is powered off.
Symptom: No sound and corrupt graphics
The MOB (Motion OBjects) checksum test failed. The EPROMs all had a checksum of 0000 meaning they weren't being accessed. The motion objects on the screen were missing.
Replaced bad GAL at board location 11S (part # 136089-1009) to fix graphics problem. Replaced missing GAL at location 6C (part # 136089-2011) with a programmed PALCE device (functional equivalent once programmed) in an attempt to fix sound. Sound worked but would either be at maximum volume or at zero. The settings would not save. Replaced bad 2816 EEPROM IC to fix the problem with saving the settings.
Symptom: Corrupt Graphics
The title screen on the game was skewed for the top half of the upper set of words ("ROAD RIOT") and during the game the sides of the road were randomly split and moved.
The custom IC at board location J18 (Part # 137419-104) had a broken leg. Swapped out the IC from a parts board to fix.