CPS2 volume fix

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Feb 122011
 

I have been looking for a fault on a CPS2 A board today. There was no volume coming out to the JAMMA connector but there was from the line out connectors (Stereo Q sound).
I couldn’t really find anything wrong as I had proved the on board amp was working.

I entered the test menu and it reported the volume was up full so I started to turn it down, when I got half way down the volume bar disappeared and the volume reported being set at 0. When I started to turn the volume up again the sound was back and it works perfectly.

Not sure what this was all about but its certainly something to keep in mind before I start poking around with a similar fault again.

CPS2 A board repair log

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Feb 052011
 

Very small repair.
I have finished making up plugs for various kick harnesses which makes it nice and easy to swap out games. I started playing my Street Fighter Zero 2 game and the sound was far too loud, when I tried to enter the test mode I found that none of the buttons on the A board worked.
I opened the case and found that the buttons had seen better days.
The buttons are normal SMD push buttons. The Capcom ones have a fifth leg which is just grounding the case of the push button and the ones I have as replacement one have 3 but since the buttons are activated via plastic switches I’m not too bothered.
Id already replaced the TEST button when I took this picture.

Changed all 3 and tested the board. The volume can now be set to a normal level.

Bubble Bobble PCB

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Feb 022011
 

Got a bootleg version of Bubble Bobble (Bobble Bobble) today. All is fine but the Red and Green signals were switched around. Its not a massive problem at all and anything is possible with all the different bootleg boards that were produced for this game.
As it is all working now I wont look into this but its worth mentioning.

Here is the pinout for this 56pin bootleg version. The same as the one floating on the net but with Red and Green switched

 Posted by at 4:57 pm

Teenage Mutant Ninja Turtles – Turtles in Time repair log #1

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Feb 012011
 

Got this TMNT2 board today cheap because it had a fault of slight graphics corruption.
The intro sequence was a bit of a mess and was very responsive moved.

I ran the built in MASKROM tests and 3K and 3L came us a BAD.

As one of the ROMs was socketed I removed it tried to dump it, I got a positive match from ROMIdent. As a little test I powered the board up without the ROM in and ran the test again, this time 3K showed up as BAD (it was removed) but 3L showed as GOOD.
I then corrupted the same ROM file in MAME and ran the MAME version, I had managed to reproduce my fault.

After much probing and head scratching I found that the enable line of ROM 3K must have a break in it under the solder mask of the PCB and was quite intermittent. This line is “active low” and when it goes open circuit (or dead) the chip enables and corrupts the data being sent as both 3K and 3L are sending their data together.
I traced the line back to its source which was pin 8 of a 74ALS04 at location 18F. I have ran a link from here to pin 12 of the ROM and the board now plays perfectly and passes all tests.


Single unit black CPS2 Marvel vs Capcom

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Jan 172011
 

Today I received my latest CPS2 acquisition, but in it black metal case and single board guise.
I haven’t seen too many of these black units for sale so when I did I jumped at the chance to get one.

When I inquired about this board the seller told me the suicide battery was replaced 6 months ago, when I opened up the case I find the original battery in place and the end of life date on it was 2011!
The battery cannot be replaced like the other CPS2 units, if I remove the battery as normal the board will suicide, the battery change has to be carried out with the power on. Not a massive problem but extra care needs to be taken not to short anything with the soldering iron whilst changing the battery.
Another thing to note is that should the board suicide its not a simple matter of erasing and writing new code to the EPROM’s. These boards have a SIMM with 48pin TSOP flash ROM’s fitted. I actually do have an adapter for these so its not a massive loss if I get a suicided one but I do prefer my boards to be original if possible.

I changed the battery and tested the game with no problems.

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