ack

There are 2 ways to get the pulse from the 4990 IC. IRQ and polling a register. The test is doing both and comparing the results. The...

Hello. I had a similar problem with a mv1b and here is what I did: -Unibios settings would not save after power off -Used the diag bios...

I would bet its going to be an issue with the NEO-BUF to the right of the NEO-I0. It might be having issues or if your board was from...

It was absolutely invisible to the naked eye (and thanks a million to my Pixel 7 phone with a 8x digital zoom) but I could see there was...

It was the BIOS chip luckily - swapped it for a known good one and the board works fine now

I would check that connectivity between the Z80 and YM2610 as well as the clock going into the YM2610...

Hi all :) I have this MV2F here, where only the first slot works. slot 1 has Bust a Move/Puzzle Bobble, slot has MS2, from what I've...

I would definitely do the cap replacement first. I misread your title/first post thinking the issue was only on slot 4.

These are my notes for slot4 on MV4 boards. This gets you info from the slot to the first logic chip. PROG (CTRG8) 01A <=> GND 02A...

whats the model number on the chips?

I would try the diag bios and see if it finds anything. Backup ram is read-only by default and requires some logic for it to become...

I will usually use a sharp/skinny pair of tweezers and test each leg by applying a small amount of side pressure to verify the leg is...

And then I remembered the old "push hard on the chip" trick. After a few minutes of poking at the NEO-IO in various ways it started...

sounds reasonable to me.

I'm pretty sure the spacing between the + and - through holes for the battery is 20mm, which is the standard distance you will find on...