Repairing a tiny ribbon cable inside a 28 year old IBM ThinkPad 701c | Hacker News Reader

Repairing a tiny ribbon cable inside a 28 year old IBM ThinkPad 701c

blog.jgc.org

100 pointsjgrahamc56 comments

I make repairs to cables like these with a very simple method: glue the two pieces together with superglue and some overlap, a few mm will do. Then use conducting glue (with silver particles in it) to restore the connection. Use a tiny brush and a microscope to apply the glue. If the currents are low (as they usually are with cables like these) this will work just fine and give a quick and long lasting result.

Haha I can picture you with your glue gun diligently applying layers

With your last name it is I that can imagine you diligently applying layers with your glue gun ;)

Anyway, I use a tiny brush, but you have to be careful not to make shorts.

Can you post some photos?

[Just to be clear, it's not a "pics or it didn't happen". I believe you, but I'd like some photos.]

Next time I do one, sure. The stuff I use is meant to repair rear window defrosters, Loctite 3863.

The cleanest way DIY way I've seen is the way TCRS handles flexgate ribbon repairs. [1]

Cut both cables. Scrape the coating. Tin the copper on both sides. Slightly overlap both cables. Tack them down, and create a solder bridge. [1 around minute 25]. Span the gap with small wire [1 around minute 29]. Finish up with conformal coating [1 around minute 57].

[1] https://www.youtube.com/watch?v=OGKucaMJEAc

Interesting, I've tried it that way a couple of times but the thermal stability of the cable is so low that I ended up melting the carrier. That's why I've switched to a 'cold' method.

A deserved "Well done" to the author, a good end to a tricky job. I wonder if it is possible to solder the two halves of a flex circuit directly together? That is, is it possible without the junction wires?

Scrape the top of one, the bottom of the other, apply solder pads to both sides then align the two and reflow the solder.

That's how these are sometimes soldered to the PC board.

Eg. https://pine64.com/wp-content/uploads/2020/09/PinePhone-USB-...

Theoretically yes, but it's harder to control the heat for the duration you need to do that. The flex substrate is pretty melty.

I would try it with a shovel tip and a whole lot of spares to get the technique down, but if I only had one shot, I think I'd go with the author's technique, one wire at a time. Perhaps with less gap between the ends, though.

I’ve done this many times and in smaller ribbons with narrower traces, this is a FPCB the substrate is kapton and it should whitstand soldering temps pretty well the trickiest ones are FFCs (the white ones)

Oh good call, yes most of my experience is with the white ones. Clearly I need to tinker more! :)

Ah. Good to know. I actually attempted something like that before this particular fix and it didn't go well. Hence I "gave up" and did it the "hard" way by hand.

The gap was to make up for the amount of ribbon I'd damaged along the way. I didn't want to shorten it too much!

It may be possible to use conductive paint instead of soldering, of course this depends if there is allowance to keep the damaged part flat. I did this on a keyboard membrane, had some damage caused by water. You need to apply the paint slowly via a toothpick, then kapton tape on the top.

Anyone know if it's possible to run a modern distribution on this? I had a bit of difficulty running full-fledged Linux on a Thinkpad X60 due to it being 32bit. Linux mint debian edition came to my rescue, but I wonder if you'd need linux from scratch or something like that.

It’s a 486, you will probably be able to run a lightweight Linux distro but it will be sloooooow.

I don’t think most distros compile for i486, minimum is i686 (not too familiar with the jargon though, before my time). Even the kernel itself was going to trash i486 support entirely. https://www.phoronix.com/news/Intel-i486-Linux-Possible-Drop

They'll have to run it with a 2.2 era kernel. Everything after that ran dog slow on these machines.

NetBSD should work according to their docs:

https://www.netbsd.org/ports/i386/hardware.html

Or OpenBSD:

https://www.openbsd.org/faq/faq4.html#Download

Maybe…? I’m not too familiar with OpenBSD but this page mentions “All CPUs compatible with the Intel Pentium or later”:

https://www.openbsd.org/i386.html

Debian still has 32bit x86 binaries: https://www.debian.org/distrib/

32-bit yes. But not 486. That port requires “686” or higher.

https://wiki.debian.org/SupportedArchitectures

There is a big slowdown from win98se to win2k, it is the same on Linux with 2.2 kernel and the 2.4. You would best using an older operating system, shutting down most of not all services and connecting through a very strict proxy

Xwoaf-rebuild-4.0 http://pupngo.dk/xwinflpy/xwoaf_rebuild.html

One floppy image, full GUI and tons of applications through busybox. Here is a video showing the full distro https://www.youtube.com/watch?v=8or3ehc5YDo

On the other hand it's not "modern", 2.2.26 kernel is from 1999

Not quite what you asked, but there was someone who did a "brain transplant" recently: https://www.tomshardware.com/news/ibm-thinkpad-701c-receives...

I run MX Linux on my T60.

Slackware-current on my ThinkPad R61i

https://mirrors.slackware.com/slackware/slackware-current/

The kernel itself is still fine on 486s and there are a couple of distros that should still technically work. Obviously nothing 'full fledged' is going to fit in the RAM on the thing or run at any sort of reasonable speed.

Gentoo is probably the easiest mainstream distro to get running just because you can fiddle with all the compiler flags and kernel options. A few people have also put together small custom images with modern kernels for this class of hardware.

The problem with Gentoo is that it will take several months to compile everything!

Yeah I would be sure to learn how to use distcc first.

Yeah, but it'll probably be more useful running Windows. At least it can play games. :)

I’ve just done jumper wires from pcb to pcb in situations like this. Six wires? Not even worth trying to salvage that ribbon cable.

I would have loved to do that but the other end of that cable is attached to the TrackPoimt which is plastic welded into the keyboard mechanism. Didn’t have much choice and I wanted to be able to remove the keyboard for maintenance if needed later.

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.

If you're going to do something similar I would suggest not relying on just epoxy. Consider adding something like a strip of denim as backing support.

Such a banged up machine but 28 years that's understandable. This made me dream, for a moment, that somewhere out there there is (perhaps forgotten?) box with this exact laptop that has not been opened just yet. Can you imagine having a blast from the past by actually being a person that unsealed this 28 years-old box for the first time.. using your nostrils to pull in that distinct smell of a brand new parts being assembled together... wonder how much a box like that unopened would cost...

They exist! This YouTuber was lucky enough to have the experience and he made an unboxing video: https://m.youtube.com/watch?v=nRVJCtREW38

Huh? That video is a review of a borrowed unit.

> And a big thanks to Sam for letting me borrow this fantastic machine for this video

Sniff around companies and universities that have IT departments that old - often they have shelves of NIB stuff that never got used somewhere.

There is another way.

Design a replacement, maybe find a script like so: https://github.com/oliveroliver/ffsc-generator

Have a PCB fabrication house make you a the flexible PCB perhaps: https://www.pcbway.com/pcb_prototype/What_is_Flexible_PCB.ht...

Or, just grab your soldering iron and some epoxy.

I think the point was that he did it as a bit of a hack. And looking at the condition of those notebooks, that's probably appropriate.

Sure, I understand and appreciate the resourcefulness of the repair as much as anyone.

I just wanted to let people know that making a new one is a viable option both in repair and new hobby designs. It hasn't been that long that it's been fairly easy to do.

I like that international object sizing tool, great idea.

I put the PDF here: https://drive.google.com/file/d/1zuhtb2eALTqONJEe4yeeajX7ltS...

Impressive work at such a small scale. I used to work with small ribbon cables frequently, but it was usually some scraping and reshaping to fix deformities- nothing as audacious as this grafting!

Fiberglass scratch pen works great for removing resist from small areas. Not sure how it would work on the presumably polyimide coverlay but it works great on soldermask.

Awesome work, happy to see you’re putting them to good use ;)

I fixed an old model M with a bit of telephone wire and tape; a connection had shorted out, and I just bridged it. The fix worked reliably for years.

I have an OP-1 that could use similar love on the ribbon cable. pretty nervous to try it though..

Have you considered designing a replacement? See my other comment. https://news.ycombinator.com/item?id=35113950

Man that must've been difficult. Great job on it!

A fun and admirable project, if a little pointless. I could never use a trackpad (even a brand new one) with any kind of reliability. I have an old, tiny, wired Logitech travel mouse for this -- it's itself a kind of museum piece, but it works.

The point in most of my little projects is my personal learning and satisfaction. I’m not going to do much with a fully working 1995 laptop but the process of getting there is the reason I do it.

Sorry if my comment sounded dismissive! I do think it's a great project.

I’m not sure why you go downvoted.

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