Author Topic: Midway Games (Read 103252 times)

channelmaniac · « **Reply #80 on:** May 07, 2014, 08:49:13 PM »

Model: Ms Pac Man
Symptom: Stuck in loop

Board was stuck trying to boot. It would occasionally flash the number "1" on the screen. Replaced the SRAM at 4R. Board then would try to go through self tests and would reboot half way through them. Replaced the SRAM IC at 4L. Tested game.

channelmaniac · « **Reply #81 on:** May 07, 2014, 08:49:24 PM »

Model: Ms Pac Man
Symptom: Dead. Garbage on screen.

When the daughter board was removed and the Z80 placed on the main board, the game played as Pac Man with a garbled Ms. Pac. (which is normal!) Checked the ROMs on the daughter board and replaced both U5 and U7. Tested.

channelmaniac · « **Reply #82 on:** May 07, 2014, 08:49:33 PM »

Model: Galaxian
Symptom: Dead

Board had damage from a previous attempted repair.

Board would try to boot but just make beep/blip noises and repeating garbage on the screen. Cleaned the legs on all the ROMs. ROM W on the daughter board had a broken leg. Patched the bad leg and replaced a bad ROM U on the daughter board. Chip at 9B had a pulled trace that needed patching. Patched the trace then replaced a bad 74LS367 chip at 8D. Board would THEN try to boot but had a RAM Error. Replaced a bad RAM chip at 5F. Board then booted but had color stripes on the screen and no stars. Replaced bad ROM at 1H to finish. Tested game.

channelmaniac · « **Reply #83 on:** May 07, 2014, 08:49:42 PM »

Model: Ms Pac Man
Symptom: Garbage on screen. Plays

Board had flickering garbage on screen but played normally. Isolated problem to the VRAM Addresser. Pins were good. Removed a wire shorting 2 pins from the top of the board and replaced a bad 74LS257 IC to finish the repair.

channelmaniac · « **Reply #84 on:** May 07, 2014, 08:49:52 PM »

Model: Ms Pac Man
Symptom: Dead. Garbage on screen.

Board had physical damage to the ribbon cable. Removed Z80 CPU from the daughter board and installed it on the main board. Game played but with the expected graphic issues. Assembled a new ribbon cable, installed it, and tested the game.

channelmaniac · « **Reply #85 on:** May 07, 2014, 08:50:00 PM »

Model: Pac Man
Symptom: Characters only move around bottom right quarter of the screen

Board had a 6-Pac mod installed.

Cleaned the edge connector and reinstalled the 6-Pac ROM card to fix rebooting issue. Replaced bipolar RAM at 3F to fix character issue. Tested.

channelmaniac · « **Reply #86 on:** May 07, 2014, 08:50:12 PM »

Model: Ms Pac Man
Symptom: Dead

Board had a short on the +5v line and an attempted repair had been made.

Replaced the regulator current pass transistor/heatsink assembly to fix short. Replaced the CPU, CPU socket, 1 ROM socket, and the ribbon cable. Tested board.

channelmaniac · « **Reply #87 on:** May 07, 2014, 08:50:23 PM »

Model: Ms Pac Man
Symptom: Dead

Jumpered 6 bad traces on a previously replaced socket and replaced the ribbon cable. Tested.

channelmaniac · « **Reply #88 on:** May 07, 2014, 08:50:32 PM »

Model: Pac Man
Symptom: Garbled video

Board was modified with the 4-in-1 game single ROM mod and an NVRAM adapter for saving high scores.

The NVRAM adapter doesn't fit well with ceramic cased RAM chips under it. Stacked 18 pin sockets under the adapter and tested.

channelmaniac · « **Reply #89 on:** May 07, 2014, 08:50:42 PM »

Model: Ms Pac Man
Symptom: Dead

Board would not boot. Voltage was sitting at 4.17 volts and the board started smelling hot. Removed the backwards installed Z80 Sync Bus Controller module and board would then come up at proper 5.0 volts. Replaced all 8 TTL ICs on the module, reinstalled it, and tested the game. Replaced the missing zip ties to hold the modules in place and replaced burnt traces on the edge connector with copper trace tape. Retested game.

channelmaniac · « **Reply #90 on:** May 07, 2014, 08:50:50 PM »

Model: Ms Pac Man
Symptom: 4 small screens of garbage on monitor

Replaced bad 74LS161 at location 3R. Tested.

channelmaniac · « **Reply #91 on:** May 07, 2014, 08:51:01 PM »

Model: Bosconian
Symptom: White screen

Replaced all of the 24/28/40/42 pin sockets on the board. Replaced bad PROM on the video board to fix white screen issue. Board worked but had intermittent graphics issues and no music. Replaced a PROM on the CPU board to fix music issue. Replaced 3 bad 74LS367 chips buffering the CPU board to the video board and 1 74LS138 on the CPU board which fixed the intermittent graphics issue but then the board had issues with text showing up as multicolored and with every other column being flipped. Replaced 3 more 74LS367 chips buffering the CPU board to the video board.

Each one of the bad LS367 were Fujitsu brand and had broken die connections as the graphic corruption symptoms would come and go if the chips were tapped. Replaced the remaining 2 Fujitsu 74LS367 chips for good measure and did a final test on the board.

channelmaniac · « **Reply #92 on:** May 07, 2014, 08:51:10 PM »

Model: Pac Man
Symptom: Graphic Corruption on maze. Sparkles on screen during attract mode.

Replaced bad character ROM at location 5E and tested.

channelmaniac · « **Reply #93 on:** May 07, 2014, 08:51:19 PM »

Model: Pac Man
Symptom: Nothing on screen

Board would occasionally flash "Memory OK" on the screen but other wise was blank.

Replaced 2 bad program ROMs and tested.

channelmaniac · « **Reply #94 on:** May 07, 2014, 08:51:30 PM »

Model: Galaga
Symptom: Dead. Nothing on screen

Board had been previously worked on. All but one of the 24/28/40/42 pin sockets were replaced. Checked for bad solder joints and shorted solder joints. Found none.

Game had no clock signals. Crystal was oscillating but the clock was missing. Replaced bad 74LS368 at 5a. Clock signal was now making it to the divider but not out. Replaced bad 74107 at 5B. Board would power up but not run. If the board was reset manually it would boot and work. Replaced C44 and the power on reset circut was now working. Board would run but had no music. Replaced bad PROM at 1D. Tested. Replaced the socket on 6M to finish replacing all the sockets on the board. Installed all new resistor packs to replace the old ones that go intermittent and retested.

channelmaniac · « **Reply #95 on:** May 07, 2014, 08:51:42 PM »

Model: Galaga
Symptom: Dead. Garbage on screen.

Board had been previously worked on. New 24/28 pin sockets and resistor packs had been installed.

CPU board tested good by substitution. Board was not attempting to boot at all. Checked the 2k x 8bit SRAM IC, the main CPU's memory, for missing signals. Jumpered a bad trace going to pin 1 from a replaced resistor pack. Tested.

channelmaniac · « **Reply #96 on:** May 07, 2014, 08:51:51 PM »

Model: Galaga
Symptom: No music or sound effects

The explosion sounds worked. Checked the digital parts of the sound circuitry and found that the /DO1 through 4 lines on the 7489 at 2A were stuck high. Replaced the bipolar RAM chip and tested.

channelmaniac · « **Reply #97 on:** May 07, 2014, 08:52:01 PM »

Model: Pac Man
Symptom: Game plays but has flickering garbage through screen.

Pin 15 was broken off the VRAM Addresser module. Replaced the adapter socket on the bottom of the module and tested.

channelmaniac · « **Reply #98 on:** May 07, 2014, 08:52:11 PM »

Model: Pac Man (96-in-1 kit installed)
Symptom: Dead

96-in-1 kit was tested by the seller of the kit and sent back to the board owner with a new ribbon cable, but board would still not work.

Checked the 2114 RAM chips and both daughter boards. Did a check of the bottom of the board for trace damage and found a solder smear between pin 3 of 6S and two traces next to it. Used liquid flux and a hot iron to remove the short. Tested board.

channelmaniac · « **Reply #99 on:** May 07, 2014, 08:52:21 PM »

Model: Ms Pac Man
Symptom: Dead

Board had attempted repair damage.

Board was stuck in reset. Replaced bad IC at 5M to fix reset problem. Replaced the 4 factory PROMs with broken legs with 4 programmed EPROMs. Fixed a broken pin on the Z80 Sync Bus Controller module. Tested.

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Author Topic: Midway Games (Read 103252 times)