Pacland repair log #2

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Oct 282018
 

Received a pacland board for a repair which was stuck with a  0 2 0 error at boot.

Normally the middle digit means it’s an program rom error and infact the second prg rom @8D had no sticker  and I immediately checked it.

 

Romident showed it was a Pacland midway rom, but the other prg roms belonged to the japanes new version.

After burning the correct 2nd rom from the jap set I was welcomed with this screen which is the service one.

The dipswitches were all set OFF and after verifying they were working correctly I decided to change all the FUJITSU 74LS257 near them which had dead outputs infact.

In the end all the Fujistsu chips has been changed because faulty: @1L, 2L and 2J!

 

With good ones changed the game finally booted but the palette was very tinted and the sprites were corrupted:

 

Verifying the sprites roms 8,9,10 and 11 these were a mess of different revisions, so using a broken pacland I put the matching roms from the new japanese set

Still the sprites were corrupted and eventually I found a bad 74ls86 ( again Fujitsu) @10F

 

With good one installed I got finally good sprites but still the palette was tinted:

 

I proceeded on the colour prom section and found that the chip PL1-2 had some outputs dead

 

Using one from another Pacland board fixed the game 100%

 

 

 

Rolling Thunder 2 repair log

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Jul 112018
 

Got this game for a repair.

At boot it displayed the following:

Using Mame source code with the memory map I could narrow down that RAM0044Eo20 was the colour BLUE ram

Desoldering it I could confirm it was bad

After replacing it I still got:

30TIP, 31TIP and 33TIP error

After discussing with Charles MacDonald he pointed me to the DUAL PORT RAM.

It checks if the last entry in RAM (460FFF) is zero, if so that’s an error (should be non-zero)
Then it checks if 460FF contains byte 6B, if it doesn’t that’s an error too

I started to probe around the dual port ram

Until I found a stuck bit on the Left side of the Dual port ram which came from a 74HC175.

After changing it, the game booted but still with TIP33 error which could be erased by pushing the start button.

TIP33 is the error related to the EEPROM which is not inizialized correctly or contain some corrupted data. Normally you inizialize it only one time but everytime

started the pcb, I got this error and offcourse all the dipswitch settings couldn’t be saved correctly.

To cut a long story short, some smart guy changed the original EEPROM with a normal 8k SRAM!

I took a spare from a faulty final lap 3  and I could finally fix 100% the game

 

 

Pac-Mania repair log #2

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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%

Pacland repair log #1

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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.

 

 

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