[Repair Log] NeoGeo MVS

    This site uses cookies. By continuing to browse this site, you are agreeing to our Cookie Policy.

    • [Repair Log] NeoGeo MVS

      Hello everyone,

      I will identify here all the repair log on MVS I could help.
      I will try to be as instructive distraillant concerning compensation for slots.
      Enjoy reading !



      Today I received a new kid in the family


      MV2FS that tells me a good


      Fairly standard, I would say

      Anyway after having opened the beast, I see that the battery is still in place, and slightly oxidized.


      Having had bad memories with a stack on my MV6, I decided to remove it immediately and replace it with a support for a CR2032 button battery.
      Finally, once soldered, it was not so dramatic as that, but better to be proactive


      Install stand below the map, it's safer if spilled, and this avoids any disassemble to change the battery.
      Do not be mistaken about the meaning, between + and -.


      Last thing to perform very important,
      you MUST desoldering resistance of 470ohms, otherwise the slot will recharge a battery that is not planned for!




      This is in place, we talk no more, one less thing to worry about.
      Returning to error


      The slot indicates 55D5, D5 means that this is the backup lower ram is at issue
      (here right above the unibios, a 43256, already changed in this photo)



      I checked that the data going well between the 74HC32 that manages and each ram.
      The lines are ok so I change the boot ram and it's alive!


      and that's yucky: oo:
      (I do not mean the choice of strategic game to test)

      Test with another


      In short, we notice that the background work roughly the texts are ok, but some sprites are streaked.
      We can limit searches, this type of display are managed by NEO-257 which are coupled to NEO-ZMC2.

      By testing the lines of the NEO-ZMC2 a logic probe, certain outputs are HS.

      I decided to change the



      and new test ...









      followed by a beautiful




      Like a jerk, I forgot to reset backup ram.
      Via the unibios, it's pretty simple, we need to start free slot play, press repeatedly managed to start and it will offer to do so.
      Otherwise, on a slot with classic bios, put all the DIP switch to 1 and on.


      Retest the blow and, as my colleague Portuguese "c'est ca it's good!"







      Small test on the second slot and ...
      tada !!!!









      Yeah, I subscribe to the second shit ...

      After test, one of the NEO-257 got bad outputs.
      Only problem, requires a multislot organ donor, except I do not have one.
      I can graft it a 74HC257 in parallel to operate at 100%, but this type of hack yucky, that does not connect me.


      Finally, I will stop there, waiting for a NEO-257.It will make a beautiful MV-1 Slot luxury and bulky!
      RL Naomi,NeoGeo,Others

      If you like my work, buy me a beer
    • Sometime those MVS slot-2 do strange things depending on wich game you play after wich other.
      Metal Slug 4 is a reknown bitch for that !!
      Those lines happen from time to time for me and very rarely I can make them go without trying
      another game before the game that's giving me trouble. I thought it was a 100% mechanical slot problem at first
      but it seems not in end.
      I also have regular issues when booting a legit Sengoku 3 on my slot 2.
      If I load it first on the slot 1 it goes 9 times out of 10 on a checksum and then it can work on both.
    • Large Kro wrote:

      Sometime those MVS slot-2 do strange things depending on wich game you play after wich other.
      Metal Slug 4 is a reknown bitch for that !!
      Those lines happen from time to time for me and very rarely I can make them go without trying
      another game before the game that's giving me trouble. I thought it was a 100% mechanical slot problem at first
      but it seems not in end.
      I also have regular issues when booting a legit Sengoku 3 on my slot 2.
      If I load it first on the slot 1 it goes 9 times out of 10 on a checksum and then it can work on both.
      Metal Slug 4 requires PCB shaving as it was manufactured too wide and causes the PCBs to warp when inserted into the cart slot causing a bad connection. If your's is already shaved then it's most likely a dirty slot with all the symptoms you describe.
    • Just mentioning, not related to the OP post, just related to the repair he had to do first. The first thing that blows when overvoltaging the boards are the RAM chips. I believe that is why most times we have to repair boards it's the RAMs that went bad...

      It's very easy to overvolt a arcade board. Another thing, which is very peculiar to the Neo Geo is the ridiculous amount of bad PCB trace faults these systems have over their service life. Perhaps the board traces were too thin?
    • l_oliveira wrote:

      Just mentioning, not related to the OP post, just related to the repair he had to do first. The first thing that blows when overvoltaging the boards are the RAM chips. I believe that is why most times we have to repair boards it's the RAMs that went bad...

      It's very easy to overvolt a arcade board. Another thing, which is very peculiar to the Neo Geo is the ridiculous amount of bad PCB trace faults these systems have over their service life. Perhaps the board traces were too thin?
      Usually it's due to a lack of a voltmeter in the cab and the constant swapping between boards. People sometimes forget to dial back the 5v line when swapping out a big size PCB for a smaller one that uses less draw. A good example is, you don't want to run a full Naomi setup then swap in a Neo Geo MV1C without dialing down the voltage.
    • Remote sensing for power supplies has been invented exactly to solve this kind of problem.
      It's nothing new actually, yet the business back then was about making everything as cheap as possible for the highest profit possible, therefore remote sensing was probably a luxury nobody would spend money onto. Let alone the need to run a shielded cable in order to make that work properly... Too many people still use wrongly sized wires (and wire count) for power connections even today; I guess making them understand remote sensing would have been asking too much.
      My 15kHz cabinet Peplos will never power up, with any item, and I am quite proud of that.