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Zaccaria "Solar Fox" Maintenance 2018

31/03/2019 - Pre-show testing

Galaxian multi-game Scramble

Pre-show testing found a couple of issues with the multi-game PCB. Firstly, the sprites on Galaxian had colour banding across the screen that was more clearly visible on Scramble. Secondly, some of the sounds weren't working properly.

08/04/2019 - Game PCB repair, part 1

Galaxian multi-game PCB on the bench Galaxian multi-game PCB with Arduino ICT

On the bench the graphics & sound issues were still present. Starting with graphics testing with the Arduino ICT passed all the RAM. A "RAM Write All Lo" clearly illustrated the colour banding on the display. Using a video probe showed the banding on IC 6M (LS273) pin 4 input (COL0). Progressing upstream to IC 2S (LS00) pin 6 output with input pin 5 high and pin 4 (RC0S) active. Moving on to the five 27LS00 sprite RAM:-

Suspecting a problem with IC 1R I removed it and the colour bars were gone. Replacing IC 1R fixed the colour bars and the sprites looked good in various games.

Moving on to the sounds I checked the sound triggers at IC 9L (LS259) and found them all inactive. IC 9M (LS259) outputs were toggling OK with sound activity. Since it was already in a socket I replaced IC 9L and the sounds were fixed. To be sure the socket wasn't bad I tried the IC in another position to confirm the IC was bad.

28/04/2019 - Game PCB repair, part 2

Galaxian multi-game, missing sprite colours Galaxian sprite RAM socket replacement

To my surprise with the PCB installed back in the cabinet the sprites were missing colours. I pressed on the sprite RAM IC's to find that the missing colours came back with pressure. I suspected the sprite RAM sockets were bad and replaced them all. On the bench the game was running OK with no obvious mechanical problems with the sprite RAM.

Galaxian multi-game

Back in the cabinet for the second attempt the game was still running OK and ran with no further issues for several hours.




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