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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 07, 2014, 06:38:33 PM
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Model: Rygar
Symptom: Horrible audio quality
This is a non-JAMMA game and the owner supplied a homebrew JAMMA adapter to use with it.
Fixed a connection on the JAMMA adapter. It was using "Speaker +" and "Audio Ground" for the speaker connections instead of "Speaker +" and "Speaker -". The game's audio came up quite a bit but it was VERY noisy with lots of digital interference in the background.
Recapped the audio section of the board. One of the caps had leaked and the others were in horrible operating and physical shape. Replaced the 2 filter caps on the +5 lines on the top board. One had its solder pad lifted so it wasn't even in the circuit. Swapped out the 220uf @16v filter cap on the +12v line connecting to the final amplifier IC with a 470uf @16v cap.
The game still has some noise in the audio, but this is from the Yamaha ICs in the circuit and is also present on the MAME version of the game. The digital artifiact noise that was in the background is now fixed.
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Model: Silkworm
Symptom: Dead
Board had a short between +5v and ground, causing the power supply to shut down. Removed incorrect mounting hardware that was causing the short and replaced it. Tested game.
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Model: Final Star Force
Symptom: Dead
Game was stuck in watchdog and would flash garbage on the screen before rebooting. Replaced bad Work RAM and tested.
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Model: Silkworm
Symptom: Single vertical line on screen
Board had a vertical line going from top to bottom of the screen, slightly left of center. Replaced bad DRAM chip at location B5 and tested.
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Model: Silkworm
Symptom: Corrupt sprites
Cleaned corroded pins on the small daughterboard and replaced a bad 42 pin socket for it. Tested.