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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 04, 2014, 08:23:27 PM
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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.
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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.
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Model: Anteater
Symptom: Sounds like a helicopter
Boardset made no sounds other than helicopter like noise.
Replaced bad ROM at 5C on the sound board and reattached loose patch wire on the bottom board. Tested.
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Model: Star Jacker
Symptom: Dead
Game is Stern licensed, hardware is Sega
Cleaned corrosion from every socketed chip's pins. Replaced bad Fujitsu 74LS86 buffering the video sync output. Replaced a Fujitsu 74LS139 in the address decoding circuit and 2 Fujitsu 74LS244 chips buffering the CPU address bus, and the CPU socket. Board was still dead.
Replaced a 74S04 in the clock circuit and a 74LS157 to get IC101 and IC102 to test properly with a Fluke 9010A. Board was still dead but came to life when all DIP switches were turned off. Replaced 2 74LS125 ICs gating the DIP switches and board would boot, but had improper sprites, no sound, and would crash. Replaced the other 2 74LS125 ICs gating the DIP switches to fix the crashing. Replaced a bad 74LS04 to fix the missing sound.
Replaced a bad 74S175, 2 corroded EPROM sockets, and 2 2016-10 SRAMs in the Object RAM section to fix the scrambled sprites. Game plays but sprites are pulsing in brightness. Replaced the 4016 SRAM in the video output section to fix the pulsing issue, but the game has red objects and garbage showing outside the playfield.
Replaced bad 74S175 in the video output section to fix the objects and garbage showing outside the playfield.
Tested.
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Model: Scramble
Symptom: Buzzing from speaker
Sound CPU was dead, but had /RESET and clock. Tested the ROMs OK and found one bad 2114 RAM Chip. Replaced the bad RAM and the other RAM chip that was too slow. Powered up the game board and heard some sputtering sounds while playing. Checked the AY-3-8910 chips and found one that was dead and the other had no 5v. Replaced 2 40-pin sockets and the bad AY-3-8910 IC and tested.
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Model: Tutankham
Symptom: Dead
Cleaned the edge connector and replaced a bad 082 custom to allow the game to boot to the game, but with garbage on the screen and lockups. Replaced a chattering 4116 DRAM at 12B to fix the garbage and a 4116 DRAM with stuck outputs at 13A to fix lines on the screen. Cleaned the legs on the Program ROMs and replaced their sockets to fix the lockups. Replaced 2 1000uf caps on the top board and tested.
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Model: Lost Tomb
Symptom: Dead. Garbage on screen.
Reprogrammed 2 ROMs and replaced 5 defective ROMs and an 8216 bus transceiver on the CPU/Video board. Reprogrammed 2 ROMs and replaced a bad Z80, 8255, and an AY-3-8910 chip on the sound PCB. The sound CPU was dead, one 8255 wouldn't read/write to the ports properly, and one of the sound chips had a dead I/O port and wouldn't receive commands from the main CPU for the sound CPU.
Note: This PCB looks like it can use the standard Konami to JAMMA adapter, but the controls are mapped differently. It requires its own adapter.
Note: If you have a conversion PCB with all the jumper wires, that version takes -5v for the audio section, contrary to what the manual and wiring diagram show. The schematic does not show the 741 op-amp present on the converted game board version that requires the -5v.