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Title: Stern Games Post by: channelmaniac on October 30, 2010, 08:23:30 PM Model: The End
Sympom: Slows down then dies. No sound. Odd symptom! Checked the clock signal and found it did slow down before the game died. Replaced the bad MB420P IC dividing the clock with a 7474. Clock signal was good yet the CPU clock was still bad. Replaced the 74LS367 buffering the CPU clock to fix slowness issue. Replaced a 1k resistor tying BUSREQ* high to fix the dying issue. Replaced the AY-3-8910 IC and 2 electrolytic capacitors in the sound section to fix the audio issues. Tested. Title: Re: Stern Games Post by: channelmaniac on May 19, 2013, 10:14:01 PM Model: Super Cobra
Symptom: Digital noise in audio output Installed missing .1uf, .01uf, and 47uf capacitors on the audio output section of the board. Tested. |