Ah, nevermind, just saw the "Midway Mfg." and "Pac-Man" markings.
Nom nom nom.
From the photo:
MIDWAY MFG. CO.
Ah, nevermind. You ninja'd my reply.
I appreciate the response, anyway. I should have looked closer before my first post.
Ah, glorious old arcade hardware, wooo!
(At least he isn't having problems with his Tempest. That machine is goes wrong in spectacularly weird ways.)
Yeah wooo! The Black_Knight pinball with its game paced woofer bass heartbeat pounding above every other game in the arcade so everyone knew you were killing it .. edging you on until you ... ahh pinball ...
Just watched a youtube video of the Black Knight(in some guys basement arcade), but my little laptop just couldn't convey the bass-beats of the Black Knights woofers that I had recalled from memory. I can't remember too many errors from this machines, but crashing that ball against the glass with powerful flipper hits, also added to the fun ... but, haven't found a digital version ...
I do wonder why there are so many unpopulated pads for (what I assume are) ROMs.
Did the ROMs get more capacious as production moved on, eliminating the need for so many of them?
I've seen this in 80s-era toys and (music) keyboards and computers. I've torn apart quite a few over the years.
I think it was just standard practice to plan out the PCB with extra holes for more ROM or RAM, in case you needed it later. Possibly even the same PCB layout re-used for multiple builds.
Different combos of chips - e.g. 4x 4116 as compared to 1x 4164, or the same with ROMs/EPROMs - could be cheaper overall. If you're talking about the section in the middle, they're almost certainly RAM/ROM, as most of the pins in the same position are connected together; that's a dead giveaway.
Designing to support both NTSC and PAL displays is another common source of unpopulated pads.
Yes, the PCB is designed to use 2K or 4K eproms. I assume they decided based on which was cheaper. The 2532's it uses have a weird pinout that is similar to a 2716.
I don't know if this means the Pac-Man machine is broken again or if you just managed to acquire a backup logic board for it.
Every now and then it goes into this mode where if you smack the side of the cabinet, the machine resets. And sometimes it will stay that way for a few days, and then be "fine". So we pulled it all apart again to try and figure out what is loose, and couldn't reproduce it, again.
So it's fine for now. Until the next time it isn't. Hooray.
I think that's a feature, not a bug. Who wants perfectly functional vintage electronics?
I used to repair these things while in high school.
Your best bet is to pull the logic board, turn it over, and look for any cracked solder joint and then reflow them with new. Any joint that looks dull / old is also a candidate. Back in the day I would reflow nearly all of the solder points and that usually fixed the problem.
Does the smacking on the side look like a power reset or a logic reset?
I remember my hometown YMCA's Pac-Man had that smack the cabinet "feature" too.
The Black Knight pinball laughs at you with a DarthVader subwoofer arcade shattering booming "Ha Ha Ha" .. ... ... yeah, yay ... ... ... anyone know how to get a free "?video-game?" version ... ... ... missing that Black Knight
What's up with the blown up/broken resistor on the daughter board left side? Right next to the Inspector 18 tag.
You might try a freezing spray to locate loose solder joints. You can use canned air held upside-down. I used to work in a TV repair shop, and they'd us that and tap around with a wood dowel to try to locate the bad spot.