2 Model M with same model # but different PCBs?

snufflecat · 15 Aug 2021, 17:16

Hi everyone,

I have to Model M's, one from 1988 and one from 1995, that are currently in a state of repair. One has a PCB that accepts an attached cable, while the other accepts a detachable cable. Pictures of the two are attached.
The thing is that they both have the same model number (1391409), which makes ordering a replacement cable quite tricky. The DT Wiki says that this model number indeed sports a detachable cable, so I cannot make any sense of why the two models therefore have different layouts/options on the PCBs.

The model numbers on the back of the plates are also identical (1387528).

Why are the PCBs different, and what do I do about ordering a cable for the one that only accepts an attached cable?
Ordering at Unicomp won't be of much help, because if I use the model # from the keyboard, I'll get a detachable cable. I know this because I did it already..

Is there anywhere I could possibly buy a new PCB, in stead of trying to find the right cable that goes with the current one?

: 1988 PCB (detachable cable); IMG_8934.JPG (1.75 MiB) Viewed 8282 times

: 1995 PCB (attached cable); IMG_8933.JPG (1.86 MiB) Viewed 8282 times

sharktastica · 15 Aug 2021, 23:14

Most of the original PS/2 Enhanced Keyboard line (13914xx) were later 'demoted' to fixed cables in the '90s. One way you could order the fixed cable that should work is by using a part number of an Enhanced Keyboard that's known to only have fixed cables such as P/N 52G9700 (from photos I've seen, they use the same cable except for the 52G9700 controller mounts the cable header upwards inside of at 90 degrees, but this shouldn't matter and likely just a Lexington vs Greenock nuance).

Alternatively, you could ask ClickyKeyboards if they have the exact 13914xx fixed cable you need.

snufflecat · 16 Aug 2021, 08:06

sharktastica wrote: 15 Aug 2021, 23:14 Most of the original PS/2 Enhanced Keyboard line (13914xx) were later 'demoted' to fixed cables in the '90s. One way you could order the fixed cable that should work is by using a part number of an Enhanced Keyboard that's known to only have fixed cables such as P/N 52G9700 (from photos I've seen, they use the same cable except for the 52G9700 controller mounts the cable header upwards inside of at 90 degrees, but this shouldn't matter and likely just a Lexington vs Greenock nuance).

Alternatively, you could ask ClickyKeyboards if they have the exact 13914xx fixed cable you need.

Aha, I see! Thanks. I've emailed customer support at Unicomp and inquired about the issue as well, but it was something like your response I was looking for. I tried ordering a replacement cable from them three years ago, using the original part number on my board, but ended up receiving a detachable cable, so hopefully this will do the trick.

retrofitit · 19 Aug 2021, 04:12

snufflecat wrote: 15 Aug 2021, 17:16 Is there anywhere I could possibly buy a new PCB, in stead of trying to find the right cable that goes with the current one?

They show up on eBay from time to time, not new but used in good condition.
I have bought two on there.

snufflecat · 02 Nov 2021, 19:04

retrofitit wrote: 19 Aug 2021, 04:12 They show up on eBay from time to time, not new but used in good condition.
I have bought two on there.

Hey there, sorry for my late reply. I ended up e-mailing back and forth with Unicomp a bit and was eventually sent a replacement PCB that accepts a detachable SDL-cable. I smushed it all together and now, with the replaced membrane, everything works great!