Flinnster's MVS mobo issues + repairs

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    • Flinnster's MVS mobo issues + repairs

      Thought I'd ask for some advice on an MV1-FS board I picked up recently.

      All seemed well on first power-on, but after a little while it starts farting and spluttering at me, despite audio in the games still working
      perfectly fine.

      So I stripped it back - no cart or edge connector to worry about, and it happens on the bare motherboard with no cart connector / daughterboard
      attached.

      Is this what happens when a capacitor re-cap fix is needed?

      Or am I looking at a deeper issue with the grounding or power on this board?

      Other MVS boards run totally fine on this cab, so I know there's nothing wrong with power, grounding or audio in the cab or loom connectors.
      Swapped out the cart connector daughterboard and bios from a working MV1-FS and the same thing happens, so I'm certain it's to do with something on this particular mobo.

      Video of the offending MVS turned Geiger counter!

      youtube link
      Wanted: - PCBs: Rainbow Islands, Rolling Thunder, Original Wonderboy
      - Parts: Naomi non-swivel castor wheel, coin mech metal clip for Dino King Door, House Extension
    • Issues are happening as the board starts to warm up. I'd start with a recap. Even though in the video you point out there's no obviously bulging/leaking caps - the electrolyte inside is probably pretty well dried out.

      Also, do yourself a favour and get rid of that horrible battery before it leaks. Replace it with a rechargeable coin cell or disable the charging circuit and install a non rechargeable coin cell. If it hasn't already started leaking, it soon will.
    • Hi guys, many thanks for your help. That battey will be gone soon, that's for sure ^^

      Luke - I tested another identical MV-1FS board and the Yamaha YM sound chip isn't getting any hotter than on the fully working one.
      For sure it's a little bit warm, compared to the other chips around it (SM1 sound rom, 6116 ram, and the Z80), but no surface of the sun / fry-an-egg heat at all.
      I compared the pins that I could trace from the YM2610 (many to the cart board connector, others to the NEO-D0, Z80 & SM1) and all seemed to match the other board I have. I can't see any broken traces, underside of the PCB looks good. Top side any battery leakage doesnt seem to have destroyed any traces, just tinted them blue a little. I've seen far worse, especially on my PGMs!

      So yep, probably a cap kit. I've found the arcadecomponents.com diagram of which to change out (26x for the full recap), but they don't sell the $3.99 kit any more, so I shall have to decipher which flavours of caps I actually need. I haven't found a specific cap shopping list for the MV1FS on my travels.
      Wanted: - PCBs: Rainbow Islands, Rolling Thunder, Original Wonderboy
      - Parts: Naomi non-swivel castor wheel, coin mech metal clip for Dino King Door, House Extension
    • The ground plane for the power area is very heavy so it's much more difficult to remove those caps. There's no real need to replace them if the board is otherwise working so it comes down to the "if it ain't broke don't fix it" argument

      If you want to replace them while doing the rest, feel free, I don't think it'll hurt anything as long as you use the correct caps.
    • lukemorse1 wrote:

      is the yamaha sound chip getting hot or are there any cuts on the bottom of the board?
      Try replacing the yamaha 2610 and see if there are any cut traces

      Weird you mentioned the YM2610 first. I've never found one bad on dozens of MVS boards I've fixed for sound issue.
      However I had many Z80s failing with the exact same symptoms described by the OP. SNK installed a normal Z80 where it should be Z80A. It's basically overclocked (just like the Z80 on CPS1 A-boards).
      Second most probable cause is RAM (6116).
      Looking for:
      - OutRun boardset even untested or not working
      - Sega Super Scaler hardware (Out Run, Model X, Model Y), even with faulty PCM chip



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    • is the yamaha sound chip getting hot or are there any cuts on the bottom of the board?
      Try replacing the yamaha 2610 and see if there are any cut traces

      Apocalypse wrote:

      lukemorse1 wrote:

      is the yamaha sound chip getting hot or are there any cuts on the bottom of the board?
      Try replacing the yamaha 2610 and see if there are any cut traces

      Weird you mentioned the YM2610 first. I've never found one bad on dozens of MVS boards I've fixed for sound issue.However I had many Z80s failing with the exact same symptoms described by the OP. SNK installed a normal Z80 where it should be Z80A. It's basically overclocked (just like the Z80 on CPS1 A-boards).
      Second most probable cause is RAM (6116).
      I bought a lot of 10 non working ones once and found missing traces under the yamaha chip causing sound issues so i recommended checking that area. Also found one with a missing trace vunder the cart slot which was a nightmare. For sure though, Ive had a couple with the z80 getting warm and fixed up with a new one. Old caps on the board causing low sounds etc.
      Some of the fun things about the neo geo hardware is that problems of all kinds pop up on various parts of the board.
      Most common things Ive experienced were the ram, Z80, and especially broken traces. Gotta love them though.