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My MV1B has one of the NEO-BUF bypass "patches" on the slot PCB, (the one on the main PCB is still present). According to https://wiki.neogeodev.org/index.php?title=NEO-BUF bypassing one/both of these, (it doesn't state which and sort of implies there's only one, when there's actually two), can...

I recently built some of @ack's excellent Neo Geo diagnostic PCBs just as a useful thing to keep handy. Testing them out on my MV1B I wasn't expecting to have any issues. However the first time I tried them with the latest v0.19a02 diagnostic BIOS, I got a VRAM 32K error on power up which I...

Having a clear out and found some extra units of things I assembled: SOLD Neo Geo AES Memory Card (£30): This is Furrtek's design using FRAM so no need for a battery. Two selectable banks. One unit remaining, not sure if they can be made now as the PCMCIA connectors seem to be EOL everywhere...

Does anyone have a spare Konami GX ROM board in their junk pile? It can be any game, it doesn't even need to work, it just needs to have at least one good connector like this that I can harvest: I have a Salamander 2 ROM board that has a slightly mangled connector that I'm looking to repair...

I have a Naomi 2 that doesn't seem to recognise any Net-DIMM that I attach. I've got a few of them with various firmware versions; 2.06, 3.17, & 4.01, and none work. I was assuming it to be a fault on the DIMM itself (buffer chip?) until I've finally gotten hold of a second Naomi 2 and they all...

I've got a weird problem on my MV1B that I've noticed with the homebrew title Hypernoid, part of the ball sprite is corrupted like this: Some observations: It doesn't always happen, not 100% sure if it's a function of the machine being powered up for a while and something is warming up As...

I've got an System 24 (currently with Quiz Ghost Hunter ROMs) that has broken audio, it just pops, sort of in time to the music if I compare how it runs on MAME. I'm trying to work out where/what the fault is. I've got the System 24 schematics, here's the audio section: There is a YM2151 OPM...

I've just recapped my M72 and as I was reassembling everything, I spotted this half-attached ceramic capacitor straddling pins 10 & 11 on IC13 on the middle B board: I initially thought it was from me flipping the board over when I was swapping over the electrolytic capacitors so I scolded...

With the original Frank_fjs-designed OLED selector not available, I've designed a new selector based around a cheap ESP8266 chip and the ubiquitous 128x64 SSD1306 OLED display. There is also a Micro SD socket along with some peripheral ICs. Here's the laid out PCB, (no 3D models currently...

Given I assembled some trackball I/O boards I figured it would be prudent to test them. I picked SDI on the S16 multi to begin with. The trackball seems to be working, (yay!), but none of the joystick controls do. I have a S16 to JAMMA edge converter that just allows reordering/remapping...

Until recently my MV1B still had the original rechargeable battery. It looked a bit grotty but hadn't leaked however it wouldn't keep a charge for very long so I figured I should replace it pronto. I bought a Dreamcast battery kit as it looked like the correct lead layout but it was only when I...

I've just finished recapping an M92 MT2 board which had a bad case of audio hum and garbled video, (fairly sure none of those capacitors should have an ESR of 200Ω). Everything seems fine now except the video is just a bit dim compared to my other boards. I can compensate for it with the pot on...

I have a C2 board that I've realised some of the player 1 inputs aren't working; namely the right direction and button 2. I've buzzed through from what I think are the correct fingers on the JAMMA edge to the pins on the 315-5296 I/O chip; both signals just pass through FLT34 or 38 and then both...

TL;DR is the M72 known to have an odd/picky sync signal? I have an M72 board (Air Duel) that I can't seem to get stable video output from. My setup is an Axunworks supergun with the VGA output going to a GBS-C board and then off to a display which works fine for a number of other boards (CPS...