View Full Version : Namco System 1 Repair Log (Galaga '88, PacMania, etc,)

4th July 2009, 01:55 AM
Symtom: No sprites (PacMania)
Bad RAM at location D4 on CPU board

Symptom: Running Galaga ’88, the large blue crystals and the large brown boulders were corrupted and pixellated
Cure: Bad mask ROM ‘OBJ1’ at location B9 on the ROM board, replaced with a newly programmed 27C1000 (a 27C100 could also be used)

Symptom: Boardset not powering on reliably, sometimes okay, sometimes not.
Diagnosis: Saw that someone had placed a 420 ohm resistor between +5 volts and pin 1 (input pin, /RESET) of CUS117 on the CPU board, then cut the track from this pin. The surface mounted custom was faulty (although it gets the /RESET signal from CUS121, but that custom was okay), obviously someone couldn’t replace this dodgy custom 117 for whatever reason. I had a spare on a parts board and replaced it and repaired the cut track, so fixing the fault
Cure: See diagnosis

Symptom: Resetting and displaying TESTING C64 (if used with the Marchen Maze ROMs) or, in test mode only, SOUND RAM3 ERROR if used with the PacMania ROMs. (CPU board fault)
Cure: Faulty 6264 RAM at location U3 (note: NOT the ‘RAM 3’ that the manual refers to as being at location S5; the Sound RAM error is the clue to it being the one at U3, even though the manual doesn’t mention it).

Symptom: Game playing but garbled graphics (ROM board fault)
Cure: Some bad/dead address lines on the Character ROMs – traced the fault back to the surface mounted custom chip 123 at location S8. Replaced the chip with one from a parts board and that fixed the fault

Symptom: Boardset would boot, wouldn’t even go into test mode (CPU board fault)
Cure: Pin 16 of the 6264 RAM at location E6 was stuck high, traced this back to the surface mounted custom 133 at location H5 where lifting the pin showed it was stuck high on the chip. Replaced the custom and fixed the fault

Symptom: Sounds f/x present but no music (CPU Board fault)
Cure: No address lines active on the 6264 RAM at location U2, data lines all dead. Cure: Bad 6264 RAM at location U2 (not reported in test mode) – replaced bad RAM, so fixing the fault

Note: The following Self test RAM errors are WRONG with the Marchen Maze code – if it reports that D6 on the CPU board is faulty then it’s really E6 at fault and vice versa !

Namco System 1 boardsets, RAM errors in test mode running PacMania code:

RAM1 Error - M5M5165P-70 at location L3

Sound RAM2 Error -
Sound RAM3 Error - 6264 at location U3

RAM4 Error - 6264/CXK5814P-45L at location H1

RAM6 Error - TMM2064-70 at location B2, D2, E2

See manual for the rest

7th July 2009, 11:05 AM
Nice work, Galaga 88 is a popular board these days it seems, was one on ebay down here a while ago, went for a tidy sum.

7th July 2009, 06:26 PM
Additionally, the boardset can be converted to other great games (such as Splatterhouse) by using Chris Hardy's patched code. :)

30th July 2009, 03:52 AM
Just added quite a few more board fixes to the first message. :)

30th July 2009, 07:27 PM
You are my god now ;)

30th July 2009, 07:31 PM
In that case, your God politely asks that you send him the reverse engineered CPS1 PALs that you created and we discussed a few months ago. :D

30th July 2009, 07:37 PM

30th March 2016, 09:29 PM

I have read your repair logs, big compliment to your work.
Hope you can help me with my problem possibly.

with my Board the problem while it tries to start, the screen is bright, but it remains black.
The Speaker makes short a noise, that's it.
When I measure with my logic probe on RESET pin of CPU I see that the signal always changes from LOW to HIGH permanent.
What could that have for a cause.
The voltages + 5V and + 12V, etc. are OK.

Possibly you have a tip.

greetings from Austria

18th April 2016, 04:22 AM
Sorry for the late reply, only just noticed that this thread had been resurrected. :)

Your board is watchdogging, which means that the game code isn't running correctly. The possible causes are many - bad program ROMs/EPROMs, bad sockets, bad logic chips in the prog ROM circuit, bad RAM, bad MCU, bad connections, corroded or damaged tracks, etc, etc, etc. If you're really unlucky it could be a combination of problems.

As your voltages are good you could also try very carefully reseating the main program ROMs/EPROMs. If you have an EPROM programmer you could also verify their contents and check that the sockets are good.

Depending on your repair skills you could then check the address and data lines, chip enables, etc. But if you're unsure how to proceed have you considered sending the board away for repair to a local repairer?