https://blog.jgc.org/2023/03/repairing-tiny-ribbon-cable-inside-28.html John Graham-Cumming's blog 2023-03-11 Repairing a tiny ribbon cable inside a 28 year old IBM ThinkPad 701c I'm in the middle of turning two badly treated IBM ThinkPad 701c machines into a single, working machine. Both machines are about 28 years old and haven't been loved in a while. I'll leave the story of dead CMOS batteries, masses of Ni-Cd leakage, broken connectors, missing cables and more for another day. [thinkpad1] But the current state is that I have cobbled together a mostly working machine from the two. However the TrackPoint in the keyboard was not working and causing a boot error indicating that the pointing device wasn't working. The reason was pretty simple. The last few centimetres of the small ribbon cable for the TrackPoint were cracked and the actual connector pads were a total mess. I do have two keyboard but one keyboard is barely working, whereas the one with the bad TrackPoint works great. [thinkpad2] Unfortunately, the TrackPoint is welded in place and so removing one and switching it to the other keyboard wasn't viable. However, cutting both ribbon cables and grafting the good end onto the working keyboard was. Here's how I did it. Using a hobby knife and under a magnifier, I scraped away the coating over the copper tracks until I had shiny copper. I tried using sandpaper but only had 120 grit available and it was too easy to break tracks. With a hobby knife I was able to just scratch enough off to reveal the six tracks on each piece of cable. [thinkpad3] The ribbon cable is only 4mm wide and there are six connections to make. I stripped out individual strands of copper wire left over from an old project. I wasn't sure what the best approach was so I used solder paste and my rework hot air gun to cover both ends in flux and tin the copper connectors. And then I hand soldered on six wires. This was really fiddly and the result is ugly but it works! To do this I had no solder on the soldering iron tip but tinned the copper wires at each end. Using tweezers and as steady a hand as I can manage just a few seconds of heat was enough to attach the wires. [thinkpad4] Amazingly that ugly thing has no short circuits and there's a connection on all six tracks. Clearly, that's very fragile so I mixed up some epoxy glue and covered the whole thing up. [thinkpad5] Here's the underside of the reassembled keyboard with my International Object Sizing Tool to give you an idea how small and fiddly that cable was to work on. [thinkpad7] The combination of solder paste to tin the connections, then hand soldering, and finally some epoxy did the trick and the machine boots cleanly into Windows 95 with a working TrackPoint and keyboard. [thinkpad6] The machine is getting close to completion now, can't wait to try out The Internet. at March 11, 2023 Email ThisBlogThis!Share to TwitterShare to FacebookShare to Pinterest Labels: hardware, retro No comments: Post a Comment Older Post Home Subscribe to: Post Comments (Atom) Labels * pseudo-randomness * babbage * hardware * anti-spam * gnu make * security * codes and ciphers * the geek atlas * retro * mathematics * behind the screens * minitel * privacy * radio Popular Posts * [Screen] Guest WiFi using a QR code On my home network I have guest WiFi configured and when guests come round they need to know the password. Happily there's a way to make... * [casio1] Pimping my Casio with Oddly Specific Objects' alternate motherboard and firmware Some time ago I bought a replacement motherboard for my classic Casio F-91W from Crowd Supply. 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