With KansasFest 2012 only a few days away by now, I started thinking seriously about whether I would try to bring a machine with slots along with me. I don’t want to travel with anything particularly rare, but I thought it might be worth it to bring a ][+ into working order for that purpose.
Easier said than done.
I have several ][+es as this point. The Bell & Howell ][+ and A2S2-10087 are both right out, they're not traveling. But the ][+ we bought in 1982, or the ][+ I got in its box, or even the 8050 "terrarium" seemed like possible candidates. Except I know the terrarium has some kind of RAM problem that would require some diagnosis, so I turned to the other two, which have for a while been kind of disassembled in my lab space.
The first step I took was to re-assemble the ][+ I grew up with. There are a couple of known problems with the motherboard. First, when I got it, it was partly covered in a stubborn bunch of goop, which I eventually managed to get out via a shower. In the process, I'd damaged one of the 74LS194 chips in the lower left corner—it had gotten trapped in the goop and lost a pin when I extracted it. The pin was actually still there, in the lower right hole of the socket, though I'd kind of forgotten about that.
So, I knew I’d need to replace that. Also, the character generator ROM had been pretty well covered in goop as well, but I have a spare that I could put in its place. I took it out to look at it, and it didn’t seem as bad as I remembered, though, so as a first step, I just replaced the 74LS194 by taking it from the II+ with the box (similar era), and put a spare 4116 RAM chip in the place where the 16K language card would plug in. (As alluded to above, I actually forgot that the broken pin was still in the socket, but it didn’t seem to affect anything, and actually it also seems to be gone now, last I checked, so I guess it came out on its own.) Another problem that I am a bit more concerned about is that one of the RAM sockets came up a bit when I was cleaning the motherboard some time ago, and though it felt like I got it back down again, I may well have severed some important connections. What kills me about this is that I didn’t document which one that was! Don’t do that. It means that if there is a problem related to this, I’m going to have to check each socket with a voltmeter or something to find out where the connection is broken.
I crossed my fingers, though, plugged in the keyboard, and powered it on.
Two problems here. First, it crashes into the monitor, so something’s not right with the world. Second, the keyboard doesn’t do anything. I don’t actually remember whether the light came on, but certainly none of the keys worked.
Time not really being on my side, I moved to plan B. I tried plugging in the lid and keyboard from the box-II+, and the keyboard did respond. But it was dirty. Also, I didn’t have any standoffs in the box-II+ pan, because I’d stolen them to re-assemble the terrarium. Otherwise, I’d have taken the spare II+ board and just mounted it in the box-II+ pan (since there was known to be a problem with the box-II+ motherboard anyway). But without standoffs, I had to do this with my childhood II+’s pan instead. The standoffs from the childhood II+ were not transferrable, they are kind of square whereas the holes for the standoffs in the other pan were round. So, I mounted the spare II+ board into the box-II+ pan, and plugged the box-II+ keyboard into it, which, though it was dirty, seemed to work.
I start to see how motherboards, pans, and case tops can kind of get separated. I’m trying to document with little post-it notes (and here) everyplace where I’ve made a substitution, so that I might someday be able to reassemble them as they were.
One bit of troubleshooting I tried was to swap the keyboard encoder boards, too, to see if I could use the childhood II+’s keyboard with the box II+’s encoder board. That didn’t seem to help, so I swapped them back. I’ll address the childhood II+’s keyboard/encoder later. Now I needed to clean the box II+’s keyboard.
I went all-out. Not content to simply take up the keys and clean them and the area underneath, I took the entire keyboard all the way apart. They keys came off, to be individually cleaned, and I unscrewed the PCB from the keyswitches.
The PCB was a bit grimy. It has a plastic cover with holes in it that can also come up, so I took off the plastic and wiped down both sides with alcohol, then wiped down the PCB. All clean. Not a super complicated mechanism. The keys, when pressed, connect two pads on the PCB, through the window in the plastic.
Reassembling the thing turned out to be harder than I’d anticipated, though. Between the holes for the screws, there are little plastic pegs by the keyswitches that need to fit into the holes in the PCB. It took a few tries, and I actually kind of bent one of the keyswitch connectors because I hadn’t noticed that it had jumped off the peg, and so the peg bent the metal because it wasn’t aligned with the hole. It took some trying to unbend it and get it back over the hole, and maybe I succeeded ok, and maybe I didn’t. It’s also difficult to put these keyboards back together, because you can’t put much pressure on the key switch (on the would-be top of the keyboard) as you reassemble it, or else the keyswitch will jump out a bit and become kind of “permanently pressed.” So I re-assembled this keyboard probably about four times before I basically got everything lined up.
And then I plugged it in, and it worked much less well than before. Most of the second row of keys (ASDF etc.) didn’t do anything when pressed, and also some of the keys in the vicinity of “X” were not responding either.
It’s a simple mechanism, but it’s a fiddly, fiddly device. I don’t know if I broke anything seriously, I suspect it’s just that something in there is not aligned properly, so some of the keyswitches are not completing the connection they need to when pressed. But if I’m going to get this to work, I’m going to have to disasemble and reassemble yet again. I have yet to try this.
Up to this point, I’d been kind of a snob about keeping original pieces together, looking upon eBay auctions with disapproval where the pan and the motherboard don’t match. But I’m really starting to see how that can happen very easily in the attempts to just get a machine working. If the motherboard doesn’t work, just set it aside for later, swap in a known-working one for now.
So, this was not a particularly successful attempt. I still don’t have a combination made with these machines that resulted in a working one. The closest is the spare motherboard in the pan of my childhood II+, with the box-II+’s top and keyboard attached, but the keyboard does’t work and I haven’t gotten further in the troubleshooting than that. I think at this point, I’ve pretty much decided that I won’t be bringing a II+ with me to KFest, there’s not really sufficient time to get one working (and it would be complicated to bring anyway).