As I have both a spare IBM 1390120 and a spare Unicomp Customizer 104, someone mentioned in my barn-find of making a hybrid of the two boards, namely transfering the backing plate from the IBM board to the Unicomp. I decided go with my older Unicomp as the primary donor of hardware since it's had a double keypress issue that's been driving me up the wall and would require disassembly to fix. I've disassembled both boards and have from the onset noticed a large number of differences between the two, some purely cosmetic, others being more quality-of-build related.
Here's some bad photos (sorry, took them with a gopro and I have shaky hands) with captions documenting their disassembly.
Oh dear, two naked keyboards side-by-side, what follows might not be safe for work! Aside from the 3 extra keys on the Unicomp, the LEDs, and the location of the PCB, you can actually feel a difference in the weight of both sides of the shell between the two keyboards, the Unicomp's lower shell has a thinner material thickness and overall it's lighter. Oddly enough, and not pictured, is while the lower shell for the Unicomp has the Lexmark-era drainage holes, which is to be expected. The back of the case no longer has the divot in it for the SDL cable, the two posts which are meant to help hold the older PCB in place are still there, though the two tabs that hold the PCB are not. I wonder why they were left in place when the rest of the shell has been modified for the newer design.
Close-up of IBM 1390120, this one's birthday is 23JAN87, that makes it 4 months and 14 days younger than me! I'm not sure who's weathered the years better, me or the keyboard...
Closeup of Unicomp Customizer 104 (UB4044A), this one's birthday is 6/27/2007, dunno what that means, 6th day of the 27th month of 2007? That doesn't sound right...
Backing plate of IBM. Looks like someone spilled something on it and never bothered to clean it, nothing a wire brush on the end of a drill can't fix!
Backing Plate of Unicomp. You can immediately tell a difference between this and the IBM, there's some weird cutout in the backing plate, and the rivets look like they were melted by someone who shoved a nail into a soldering iron and used the head to melt the rivets (you can see the marks from a nail head in the rivets), they aren't as uniform as the IBM rivets. I'm not sure if I like the fact the keyboard has a more human touch to it than the IBM (which likely had a machine do the rivets), or if I'm non-plussed about the clear difference in quality of build. I know around the time this board was assembled that Unicomp was just about on death's door financially so I'm not going to fault them for having to do things cheaper to stay alive.
The two backing plates side-by-side, I know it's pretty blurry but you should be able to tell that the Unicomp plate (left) is almost half the thickness of the IBM (right) one. The 1390120 is a much heavier keyboard all around, and quieter as well, the difference in backing plate thickness must be part of that, we'll find out once it's been put into the Unicomp.
Time to remove the rivets from two keyboards!
Somebody puked IBM parts all over my living room!
And then they puked Unicomp parts! It will probably be hard to tell, but if you look at the IBM barrel plate, it has 3 rubber tubes located along the edges, the Unicomp lacks these and there is no way to fit them into the newer barrel plate. I suspect that these also affect the amount of noise generated.
IBM-made hammer and spring assembly.
Unicomp-made hammer and spring assembly. Identical in every way except hammer colour, which is white instead of translucent. It also has a different mould number on it. Some of them are a little rough around the edges, as if they hadn't spent enough time in the part tumbler getting cleaned up. The Unicomp had a lot more dust and random crap between the bottom of the barrel plate and the rubber mat, including some debris right around the ; key, I wonder if that's why I was having a double keypress issue with that key. Keep in mind that this particular board has been through the hell that is a college student's apartment, I often wonder how I survived, let alone this keyboard.
I use a razor blade to sheer off the plastic rivets, if it wasn't for the fact over half of the ones on the 1390120 had popped off of their own accord over the past 2 and a half decades my fingers would be weeping bloody tears of pain. The Unicomp rivets were much harder to remove, probably due to the extreme variation in thickness. Hard to tell, but IBM rivets are on the left, Unicomp ones are on the right.
Tune in next time where I start drilling out the Unicomp's barrel plate and assemble the hybrid board. Aside from the backing plate from the IBM, I will also replace all of the Unicomp hammers (less 3) with the IBM made ones. 58 bolts, nuts, and washers, why do I do this to my poor hands?
