Author Topic: Midway Games (Read 102631 times)

channelmaniac · « **Reply #200 on:** February 07, 2015, 07:07:46 PM »

Model: Ms Pac Man
Symptom: Random reboots and bad sound

Replaced the 2200uf cap in the audio circuit that had very high ESR readings. Replaced ribbon cable and 2 40-pin sockets on the daughterboard to fix reboot issues. Tested.

channelmaniac · « **Reply #201 on:** April 07, 2015, 08:01:59 PM »

Model: NBA Hangtime
Symptom: Every ROM bad on board. Missing sounds.

Resoldered the custom DMA Controller IC and tested.

channelmaniac · « **Reply #202 on:** July 28, 2015, 04:37:13 PM »

Model: Pac Man
Symptom: Dead

Replaced bad CPU and tested. Installed missing zip ties on daughterboards and tested.

channelmaniac · « **Reply #203 on:** July 28, 2015, 04:37:55 PM »

Model: Ms. Pac Man
Symptom: Dead

Replaced bad CPU and tested. Installed missing zip ties on daughterboards and retested.

channelmaniac · « **Reply #204 on:** July 29, 2015, 08:38:13 PM »

Model: Ms. Pac Man
Symptom: Dead. Stuck in reset. Extremely faint image on screen.

Replaced Sync Buss Controller IC socket and CPU socket. Interrupts and data lines were all going crazy. Broke out the Fluke 9010a and notice that three of the Program ROMs read properly. Cleaned the pins on the ROM at 6E and then it read properly. Board failed all RAM tests. The RAM reads would return random data at times and the control signals to the RAMs weren't quite right.

Replaced 74LS161 at 3R and the board booted. The 1H, 2H, and 4H signals were not dividing properly which threw off the control signal timing to the 2114 RAMs. Replaced the video output PROM at 7F with the proper PROM to restore video output. Someone had put a sound PROM from location 3M into that socket and its open collector outputs (not to mention different programming) wouldn't work properly in that circuit.

channelmaniac · « **Reply #205 on:** August 01, 2015, 04:10:32 PM »

Model: Galaga
Symptom: Dead.

Board had attempted repairs.

Replaced all the 24/28/40/42 pin sockets and old style resistor packs on the CPU board and video board. Replaced the 07xx and 00xx customs on the video board as they had multiple missing legs.

Tested and burned board in for several hours

channelmaniac · « **Reply #206 on:** August 13, 2015, 07:57:09 PM »

Model: Ms Pac Man
Symptom: Dead. Stuck in reboot with garbled characters on screen.

Board had attempted repairs done to it.

Looked board over and saw where the IC at 3H was replaced poorly. Fixed a solder short on one of the data lines and replaced the socket of 5F to fix the garbled characters. Board was still stuck in watchdog reboot.

Broke out the Fluke 9010A and the Z80 pod and discovered the ROM checks failed with random checksums. Cleaned the pins on the ROMs and they still but had steady, incorrect checksums. Fixed broken trace for data line D6 between the CPU and the Z80 Sync Buss Controller module. Tested board.

Replaced radial caps at C2, C5, and C29 with proper axial caps and retested.

The moral here is if you're repairing a board and it gets worse while you are repairing it then STOP and check your work. If the person who previously worked on this board had done this they would've seen the whisker short on the 7489 chip they replaced. Fixing that would've been easier than them replacing the CPU, Z80 Sync Buss Controller, and VRAM Addresser sockets with machine pin socket strips. When they did that they damaged a trace on the data buss further damaging the board.

channelmaniac · « **Reply #207 on:** August 13, 2015, 07:59:27 PM »

Model: Pac Man
Symptom: Missing parts.

Replaced missing power regulator transistor, voltage regulator IC, and volume control pot. Installed missing Sync Buss Controller and VRAM Addresser modules. Tested. Board was stuck in reboot. Replaced bad Sync Buss Controller socket and retested successfully but sound was garbled. Replaced bad PROM at 1M then repaired 2 burned edge connector traces with copper tape and retested.

channelmaniac · « **Reply #208 on:** August 13, 2015, 09:09:55 PM »

Model: Ms Pac Man
Symptom: Reboots and has garbled text/graphics.

Board would work fine without the Ms. Pac daughterboard installed but would be stuck with crashing and restarting upon installation of the daughterboard. Tested with a known good daughterboard and cable. Tested with a known good set of Z80 Sync Buss Controller and VRAM Addresser board and it would still crash at the attract screen and restart or would get stuck in a loop with a single "1" on the screen.

Replaced bad socket at 5F to fix the garbled text/graphics issue. Tested board with a known good set of ROMs. Board passed self tests but my BK 560A identified a bad 2114 RAM at 4K. Replaced the RAM and the crash/reboot still existed. Replaced the 74LS367 ICs at 6R and 6S thinking that maybe they had flaky inputs and that the extra buss length from the ribbon cable was causing the problem. It did not fix the issue.

The system would boot if the daughter card was installed but the 3 ROMs on it removed. It would also boot with a Two Bits Ms. Pac upgrade card at the end of the cable and with a 6-Pac upgrade board installed. Checked the 74LS42 at 7N and found that if pin 2 was probed the board would jump out of the stuck on "1" screen and start to reboot. Replaced the 74LS42 and the board immediately sprang to life.

channelmaniac · « **Reply #209 on:** August 30, 2015, 04:00:30 PM »

Model: Rampage World Tour
Symptom: Missing colors. Fails self test.

Replaced 5 missing SMT caps and 2 missing SMT coils to fix color issues. Replaced bad ROM and tested.

channelmaniac · « **Reply #210 on:** August 31, 2015, 06:59:38 PM »

Model: Mortal Kombat II
Symtpom: Dead. Lines on screen.

Reflowed custom DMA controller IC at UE13 and replaced dead battery. Set Free Play mode and tested. Board worked but the sound output was sputtery for the first minute. Recapped audio board and retested.

channelmaniac · « **Reply #211 on:** October 18, 2015, 06:43:29 PM »

Model: Galaxian
Symptom: Stuck in boot loop

If you watch it carefully it will flash "BAD ROM" on the screen between reboots.

Used a Fluke 9010A and ran checksums on the ROMs. Replaced bad ROM at 7U and retested.

Board was repaired as part of a "repair party" at the shop using one of the participants' Fluke 9010A in a hands-on walk-through of using it to repair a board.

channelmaniac · « **Reply #212 on:** November 14, 2015, 12:00:26 AM »

Model: Mortal Kombat II
Symptom: Dead.

Board had attempted repairs done to it.

Replaced CPU and Custom IC PLCC sockets, reflowed the custom DMA chip, and tested. Board booted with ROM errors. Installed missing ROM daughter board and retested only to find 2 ROMs not working on the daughterboard. Repaired a bad trace on the main board to fix the issue and tested.

channelmaniac · « **Reply #213 on:** December 24, 2015, 09:13:10 AM »

Model: Ms Pac Man
Symptom: Dead

Board was missing parts.

Board would not power up and had a short on the 5v line. Replaced shorted zener diode in the power supply to fix missing 5v. Installed missing CPU, Z80 Sync Buss Controller, VRAM Addresser, and 74LS161 at location 1E. Repaired power traces on the board's edge connector with copper trace tape. Tested board.

Board would now play but had distorted ghosts on the attract screen and the board would play Pac Man with a Ms Pac character that looked as if she was "walking on her lips." This was a ROM mismatch. The ROMs at 5E/5F were Ms. Pac character ROMs.

Pulled the ROMs and installed a customer supplied Super ABC 16-in-1 kit at their request. Retested board.

channelmaniac · « **Reply #214 on:** January 11, 2016, 12:41:04 AM »

Model: Pac Man w/6-Pac kit installed
Symptom: Garbage on screen and sometimes doesn't boot.

Reseated the ROM daughter board at 5E to fix the lines and garbage on screen. Cleaned the edge connector next to the CPU socket where the 6-Pac kit was plugged in. Tested.

channelmaniac · « **Reply #215 on:** January 18, 2016, 09:48:29 PM »

Model: Ms Pac Man
Symptom: Garbage on screen. Edge connector was heat damaged.

Repaired the edge connector with copper trace tape and tested. Board was not booting. Pushed down on the ROMs and noticed that when the ROM at 6J was pushed down it would boot. Removed the Mask ROM at 6J and noticed that pin 24 was broken. Replaced the Mask ROM with an EPROM and tested.

channelmaniac · « **Reply #216 on:** January 20, 2016, 09:47:36 PM »

Model: Ms. Pac Man
Symptom: Dead. Flashing garbage on screen.

Part of the garbage was the number 2. Replaced bad ROM at 6H and a hacked 2732 EPROM at 6F and tested. Board would play but was playing Ms. Pac Attack instead of Ms. Pac Man. Replaced a ROM at U6 on the daughterboard with one running original code. Tested.

channelmaniac · « **Reply #217 on:** January 20, 2016, 09:49:21 PM »

Model: Pac Man
Symptom: Dead. Nothing on screen.

Booted the board a couple of times and it showed vertically rolling garbage on the screen - it was missing some of the vertical clocking signals. Replaced a dead 74LS161 in the clock divider circuit at 2R and tested. Board was standard speed Pac Man. Replaced the ROM at 6F with the speed-up hack per customer request and retested.

channelmaniac · « **Reply #218 on:** February 09, 2016, 07:16:57 PM »

Model: Mortal Kombat 4
Symptom: Random problems

Board would play dead and not boot. When it would boot it would suffer random failures and reboots and sometimes a scrambled screen.

Board's failure was the result of a problem in the security chip circuit. The clock crystal would randomly stop and start oscillating. Reflowed cracked solder on the surface mount capacitors and 4MHz clock crystal. Power cycled board multiple times over several hours and ran it through 128 cycles of built-in burn-in tests.

channelmaniac · « **Reply #219 on:** March 06, 2016, 03:40:07 PM »

Model: Driving Force (Modified Galaxian board)
Symptom: Dead

Board was missing a jumper wire (and it was a terrible game) so the board was de-converted back to Galaxian. Removed all the kynar jumpers then pulled the ROM daughterboard and replaced it with a Galaxian one. Removed the stacked PROMs at 6L and replaced them with the proper PROM from a salvage board. Removed the stacked EPROMs at 1H and 1K and replaced the one at 1H with a mask ROM from a salvage board and 1K with a freshly programmed 2716 EPROM.

Board would boot but had no starfield, no color, no missiles, and both the ship and enemies were stuck in place on the screen. Resoldered cut pin 15 on the IC at 2B and cut pin 10 of 5E and tested. Replaced 2 bad 10,000uf capacitors in the power supply section and retested.

Goodbye Driving Force, hello Galaxian!

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Author Topic: Midway Games (Read 102631 times)