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NLG Users Repair Logs and Other Ramblings. Request your very own topic. Just ask any site staff. => Channelmaniac's Arcadecomponents' Old School Repair Logs => Topic started by: channelmaniac on May 02, 2014, 10:07:38 PM
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Model: Space Force
Symptom: Dead
Board was missing the audio amplifier IC and appears to have the same pinout as Galaxian.
Sound CPU was running, main CPU was dead. Reset circuit was dead. Replaced a bad 74LS04 in the power on reset circuit and tested. Board would sometimes boot incorrectly and would not coin up from Coin 1. Resoldered the main crystal, replaced a bad 74LS244, and tested. Pinned out the audio amp chip and replaced the missing part with an LM380. Board would reset if the volume was barely turned up. Traced the edge connector and found Speaker - was connected to the reset circuit. This must've been a slam switch input to reset the game. Cut the trace and connected the edge connector to ground so the board could be plugged into a Galaxian cabinet. Retested board successfully.