Extending a ribbon cable, easily? - Page 1
Forum section: electronics / beginners

author: BlackICE
author_rank: Regular Contributor
timestamp: December 22, 2022, 08:45:51 am
content: I have a ribbon cable for a 3d printer that on one side has the cable split into many JST connectors and on the other side has a dual row IDC connector 24pin with 2mm spacing. The cable was too short so I bought a longer ribbon cable and made another one. Crimping a bunch of JST connectors (PITA) on one side and clamping and ICD connector on the other side was easy. This took some time to complete and I still had a error where one of the pins wasn't seated correctly so I fixed that and it seemed to be OK. After some testing and use another connection went bad. I lost connectivity on one of the wires. There is a break somewhere that I couldn't find.I dread making another one because of the time it took and the error I made the 1st time as well as this cable will be in constant motion and probably will break more wires with use. I thought I could just daisy chain another ribbon cable with easy to use IDC connectors but the pinout will not be the same. I could make a PCB with header connections to join 2 ribbon cables with IDC connectors, but that would take at least few weeks turn around time. The cable has a 2mm or 0.79" spacing makes finding parts harder and rules out hacking something together using a easy to get 2.54 perf board.I like the idea of daisy chaining 2 cables together, because the cable section that constantly flexing will probably fail and needs to be periodically replaced, hopefully without crimping a bunch of JST connectors each time, but just using IDC connectors.;Any better ideas from anyone would be appreciated.

author: Infraviolet
author_rank: Super Contributor
timestamp: December 22, 2022, 06:31:00 pm
content: While you wait for a PCB how about buying some existing 2mm to 2.54mm adapter PCBs and then soldering those to stripboard.These sort of things:https://www.amazon.co.uk/gp/product/B07V873N52/https://www.amazon.co.uk/Adapter-1-27mm-2-54mm-Wireless-Modules/dp/B094JRBMR1/Use it to extend from the JST end rather than the bulky single end, unless you can find such an adapter board with enough holes to cover for the neds of the bulky end.

author: Infraviolet
author_rank: Super Contributor
timestamp: December 22, 2022, 06:34:49 pm
content: Some photos of the current problem cable might help too.

author: themadhippy
author_rank: Super Contributor
timestamp: December 22, 2022, 07:09:12 pm
content: just buy the extension cable with a female connector on one end and male on the other

author: EPAIII
author_rank: Super Contributor
timestamp: December 23, 2022, 02:56:39 am
content: It sounds to me that your ribbon connectors do not have any strain relief. When I built with ribbon cable connections, I always choose IDC connectors that had strain relief. That strain relief usually added a 180 degree fold and perhaps another 90 degree one in the ribbon cable. So any flexing could not reach the point where the insulation displacement connection took place. I never had any problems with the cables. And using ribbon cable and IDC connectors saved me days of work on projects. Properly done, they are fast and reliable.Data sheet for 3M IDC ribbon cable socket. Notice that the strain relief is sold as a separate item.https://multimedia.3m.com/mws/media/22265O/3mtm-idc-ribbon-cable-socket-891-series-ts0449.pdfI also wonder if your connectors and cable are compatible. Perhaps the cable wire gauge is too small for your connectors.

author: BlackICE
author_rank: Regular Contributor
timestamp: December 23, 2022, 10:44:10 am
content: I used a strain relief. I didn't find the exact location of the break but it wasn't near any of connectors. I found what I thought was a break by flexing the cable causing an intermittent connection. I cut that section out and jumper across it but it still was bad. So I going run a separate wire for the broken one soldering it to the good section of ribbon cable. I hope that holds up until I can make a PCB to bridge to IDC cables. I might have contributed to the cable's demise by folding it to fit inside a cable mgt. sleeve.Finding 24 pin 2mm spacing extenders isn't easy. A common strait through cable won't work pin 1 is wrong, switched with pin 2. With Covid any guess of the turn around time for PCB from the common low cost companies in China?

author: themadhippy
author_rank: Super Contributor
timestamp: December 23, 2022, 11:12:47 am
content: Quoteon the cable you use as an extender a straight through is what you want as the swap is already taken care of in the cable your extending.As for availability my local go to place seems to stock the bits,and will do custom builds if you ask em nicely,https://www.toby.co.uk/cable-wire-to-board/

author: radiolistener
author_rank: Super Contributor
timestamp: December 24, 2022, 11:52:13 pm
content: Quote from: BlackICE on December 22, 2022, 08:45:51 amSuch cable max length is limited by port input/output drivers impedance and frequency. If you extend it's length you can get communication errors.

author: BlackICE
author_rank: Regular Contributor
timestamp: December 25, 2022, 12:02:04 am
content: The only signal wires that possibly can be problematic is a pwm signal to a bed leveling sensor. Another four wires are used to power a stepper motor. Those two devices are not used at the same time. Another small problem area is two pairs of 28 gauge wires are used to power a 50 W 24 volt heater. So the power loss is not negligible but not significant.