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Zaccaria Super Cobra Maintenance 2017

30/05/2018 - Pre-show test

Super Cobra sound PCB L-1200-1B Super Cobra sound PCB with ICT

Pre-show testing found that the game had no sound. The +12V, +5V & -5V power supplies all measured OK in the cabinet so I pulled out the game PCB for bench testing. Testing with the Arduino ICT flagged a failure in IC 6C (2114) with all other tests passing, including all 6 channels of the two AY-3-8910. Replacing IC 6C fixed the sound.

01/06/2018 - Super Cobra spare PCB #PA20180531, main repair

Super Cobra main PCB with ICT Super Cobra, running Super Cobra main PCB ROM set

I hadn't yet prepared a spare PCB set for use in case of a failure during the show so I started work on another set. Initial power on showed reasonable video output but the game didn't boot. The watchdog was triggering.

Inserting the Arduino ICT passed all the RAM and interrupt tests but the ROM CRC did not match anything I'd previously tested. A ROM read returned completely mismatched data and the ROM CRC check was stable. IC 2C CRC was 0xba9d4152 and IC 2E 0xf9b77b27. According to MAME these CRCs matched the Super Cobra RA1 ROM set that uses the "Konatec" encrypted CPU that I didn't have. I programmed a complete unencrypted replacement ROM set and with those fitted the game booted up and appeared to be working OK except the sound wasn't working properly.

02/06/2018 - Super Cobra spare PCB #PA20180531, sound repair

Super Cobra sound PCB with ICT

Inserting the Arduino ICT passed all the RAM tests but the ROM CRC was unstable. Pushing on IC 5C (2716) caused it to sometimes pass and sometimes fail so I suspected a bad ROM socket. Replacing the ROM socket and cleaning the IC pins fixed the sound.




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