Recent content by Hairy Otter

Here is how I did it: I took out the zener diode hrp100, the diode 1s1588 along with the resistor 220. Then I but the dionde 1s1588 where the zener diode used to be. How I came up with this you can read here: Primary Post The end result looks like this:

Hello, I have a faulty MV1A on my bench, which is in watchdog mode. It does this with every BIOS (original, Universal and Diagnostic) Controle lines of the bios look ok. Continuity to the 68000 looks fine, but with my logic analyzer I see Q4 and Q0 are stuck high on both bios and 6800? Does this...

Sorry for the double post, but I waited for over a week with no result in the original thread: "The bad battery thread". original post link. :help: Is there somebody out here who can help me?

This is what I got from looking on the board. I did some experiments on a scrap board. First I removed old battery along with the 220 resistor, but this hadn't the effect I expected. With the power on the voltage on the anode of the 1S1588 was 0V, but on the cathode it was still 4.2V? The +...

I've revived some 4 slot mvs boards, none of which had battery leakage, but to be on the safe side I just ask. Do I better exchange these batteries? (The boards are labled:NEO-MVH MV4FS) With other boards I've repaired, I always put in a non rechargeable 2032 battery after removing the load...

After I revived some 4 slots from my "too hard"-pile, I took a look at the old one slot that was in there. It started with a video memory error as is stated on the label. I fixed this by replacing one of the video rams. Then I got a calendar error. This seems to be a problem of a bad crystal, as...

I'm trying to fix a MV2F with a Z80 error. First I swaped the Z80 and the SM1 with those from a working board. The working board still working, the broken one is still broken. Then I got my new toy, the logic analyzer. Give this a try to find the problem. Now I found D1 on all components acting...

I have a Top Hunter cart with no sound. The problem is in the cart, as it does this in al my Neo Geo boards (1-slots 2-slots, 4-slots and 6-slots) All contacts are clean and there are no brocken traces. But the datalines SDD0-7 are high impedance. And the G* pin on the M1 is stuck high. In my...

I've got myself a 2 slot mvs board with a watchdog problem. The connections all seem to be allright. But if I look at the Address lines on the 68000 I find the A4 and A5 (pin 32 & 33) to stay low, other Address lines give a short pulse to high with each kick of the watchdog. What can cause...

Hello, I've brought back some MVS boards back to live now, but I still can't find a good way to remove the protective cardboard wich are on all the boards. To me it seems that corrosion is wors under the foam. Also the underside of the battery is always covered by it. So to replace it you need...