Recent content by neolithicau

Looks like a stuck-high address line but it could be as simple as a sprite ROM being out of whack. You should remove and reseat all the ROMS.

(I'm no expert, but) Something is grounding the battery circuit and draining it slowly. I had an issue like that on mine from an incorrect trace 'repair'. Maybe check for a solder bridge in the backup area?

My Astro City apparently came from Sega World Sydney. The guy I bought it off had a container of them that he kept in the decade past its closure, eventually getting a few of them back into a sellable condition (including my own, which similarly needed CRT work soon after I bought it...). I've...

So I have Tekken 1 and Tekken 2 Ver. B boards. Tekken 2's CPU board had a bunch of issues, so I've switched it with the CPU Board from T1. Regardless of that, both games spit out garbage and irritating samples in the music tracks, which leads me to believe the problem is specific to the...

Been flat out the last couple of weeks - finally had a chance to check this out a bit more. I probed the traces all the way back to the Neo-F0 Pin 54 - all continuity checks out. I also probed down the other way, to AS04 (74AS04N inverter - feeds/gets fed by the Neo-IO Pin 19 and SFIX Pin 20)...

Thanks for the tips. I just gave it a quick check - 5.07v so all good there. I won't be able to get into this proper again until tomorrow (it's just after 12am local) but I added a replacement chip onto an order I already had just incase.

I imagine said 74ls244 isn't supposed to have a bunch of "open" pins... I can't get the probe in there with the top board/game in though... Readings: 1 H 2 Open 3 L/H (Narrow high/low pulse... isn't expensive enough to differentiate) 4 Open 5 H/L 6 Open 7 H/L 8 Open 9 H/L 10 L 11 Open 12 H/L...

Thanks for your suggestions - I hadn't found that page in my own searches!

A dinosaur of the Neo-Geo fleet, I recently acquired a broken MV1 off eBay. Inititally it booted to a Work RAM Error screen as a result of a minor battery leak, with some evidence of corrosion around the closest two surface mounted Sony RAM chips. I cleared all that up with isoprophyl, cut the...

Buffet you're a genius. The H Hold was just out... Thanks!

Just when I thought the troubleshooting party was finally over. See the pics here. Basically after 15 minutes or so I start to get a curl on the vertical right-hand side. I've done a FULL capkit (including filter and NPs) and it was operating just fine until last week. B+ is spot on. A real...

Right on. Thanks for your help at anyrate!

Turns out I was looking at the wrong parts list originally... Anyway, for HS Lim (VR452) I was quoted 30K by the repairer, so that's what I replaced it with. The actual list of Nanao parts in the Touring instructions calls for 3.3k there as well...

Thanks for the suggestions guys. I've already given it a quick crack with the isopropyl spray, and dialed it each way a bunch of times - it didn't really help sadly. The HS Limit pot was also bad and has been replaced. I actually sent the chassis to a repairer here in Australia and it was sent...

I've kind of vaguely mentioned this over a few threads here, mostly involving an extremely stubborn Sanyo monitor, but this is the first time I've documented it properly. This is the culmination of about three months of on-and-off work on an old Taito Space Invaders cocktail I bought off eBay...