Nov 092017
 

I bought a faulty Pac-Mania mainly for spare parts but I gave him a chance and tried to repair it

The game was missing sound roms, after replacing them, game booted and you could play but the screen was totally a mess.

After some blind testing I started test all socketed custom chips and rams against new ones and I eventually found the culprit

in the “text” ram @L5!

It was so bad that it totally covered the screen with junk graphics

Replacing it fixed the game 100%

Nov 092017
 

Got this Pacland, Sidam version, in mint conditions  for a repair

The game had some color bitplanes of the sprites shifted to the left as you can see from this pic

The sprites are handled by CUS29 and there are two 2149 rams connected.

Piggybacking a good 2149 ram on top of the one @3T restored good colours

Testing it out of circuit confirmed it was bad

The game had no other faults and was 100% fixed

Rolling Thunder repair log #2

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Feb 042017
 

While I was playing this game from my collection  ,I discovered it was missing all the samples (gun shots, walk and so on).

The game is a Namco system86 with an additional daughter board used for the samples

Before beginning the troubleshooting I searched on Internet for a similar problem and found a repair log

where all the caps on the daughter board weere changed , restoring the samples.

I am not a fan of changing caps randomly so thanks to Atari I checked the schematics and

found that the on the daughterboard there is a little circuit which produce 24V out of the 5V for the op amp.

Around that circuit there was a hissing noise therfore I checked if the 24 volts were present which was confirmed.

I proceeded with my sound probe to see if from the op amp I could hear the samples but when I turned on the game,

it continued to reset itself….the watchdog was active.

At this point I was a little puzzled and tried to disconnect the daughterboard which granted me with the game that booted

but with missing background and crashed as soon as the attract mode began.

I took some customs from various Namco games and checked if the game booted but no luck.

Also I hadn’t another Rolling Thunder to check the two customs on the daughter board therefore I put the pcb apart for sometime.

After some weeks i resumed the pcb and without much hope I checked various TTLs until I found a 74LS244@A1 on the daughterboard

which had pin 12 not oscillating properly while the input was healthy (Fujistu part….)

 

I piggybacked it with a good one and the game booted briefly correctly.

After changing it, I returned to the original state with the gameplay without samples.

I tested the output of the op amp TL074 with the sound probe and I could hear the samples.

Ttherefore there could only be one cause which was the capacitor @C1 placed between the output and the daughterboard connector, which infact was tested as open with an ESR meter

Changing it restored all the samples.

 

 

Gaplus repair log

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Jul 022016
 

The game belonging to my personal collection didn’t boot anymore after several years kept in storage.

Foto 02-07-16 10 26 28

 

Game was in mint condition but the address decoder custom 34 had lot of oxidation on the pins (common problem on these custom chips) so I proceeded to clean and reseat it paying particular attention to avoid breaking pins which generally are really weak.

Game booted but it developed the following problem

 

Foto 02-07-16 10 28 49

 

After probing around on the rams and TTL for suspicious signals with no luck I decided to dig up my dead Gaplus board which I kept in my garage for Namco customs spare parts and checked one by one each custom.

After changing the CUS20 (tilemap and sprie address generator) the problem was fixed

Foto 02-07-16 10 30 38

Foto 02-07-16 10 26 38

Foto 02-07-16 17 33 44Foto 02-07-16 17 34 11

 

Another Fujitsu chip left our world.

Super World Court repair log

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Jan 312016
 

Another pcb which was part of the cheap deal.

It was completely dead. Given that it is not an interesting game I was about to use it for spare parts when I asked my friend Caius if he ever repaired a Namco NA-1

He told me he once repaired one with a capacitor connected to the reset circuit of the 68000 which faulty and didn’t produce the reset signal.

I tested mine and to my surprise the reset was stuck low.

I changed the capacitor smd 22uF @C5 with one 1uF which I had available and the game booted.

Unfortunately the sound was completely missing, so I probed with my portable amplifier some smd capacitors which are know to be leaking very easily and I found one which interrupted the sound to the main ampli.

After changing it, the sound was very low with lot of background noise.

To end a long story short, I recapped many small smd caps with new ones and restored full volume.

This is a common problem with Namco NA-1 pcbs

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