EEVblog Electronics Community Forum
Electronics => Repair => Topic started by: pamphonica on February 23, 2018, 04:18:18 pm
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I am trying to get some HP85s I found last week up and running. They are all faulty and very dirty!
The main problem currently is faulty ribbon cables. These are "FFC" type, with flat conductors sandwiched between plastic surfaces, with a portion at each end un-insulated.
These have delaminated over time, sometimes ending up as nothing but two plastic sheets and a handful of metal confetti.
They are the old-fashioned 0.1" (2.54mm) type.
I can't afford to get new ones manufactured - manufacturers can apparently do 2.54mm but want at least 500-1000 MOQ. There are 8 cable types (various lengths, 20, 17 and 11-way).
New surplus are all much smaller pitch (1mm or 0.5mm)
I can (just) hand-make new cables but I only have a couple of 18" long existing cables to canibalise.
I could fit different connectors but it seems a shame to make the machines non-original for future generations.
It's also a real shame to see these noble computers ("calculators" in HP-speak) unable to function for want of a few cables.
Does anyone know where I can get a small reel (50m?) of 2.54mm/0.1" 20 conductor FCC cable? Or some surplus 1"/2.54mm pitch cables at least 20-way that I can cannibalise?
Any ideas?
Many thanks
Jeremy
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If they're regular 2,54mm pitch, you should be able to use standard jumper-wires available from ebay.
https://www.ebay.de/itm/Male-Male-Female-Female-Jumper-Wire-Dupont-Draht-Kabel-Linie-Ribbon-Kit/311715750360?hash=item4893b4e1d8:m:mGWlue6bHSXbZjl3sZD9nXw (https://www.ebay.de/itm/Male-Male-Female-Female-Jumper-Wire-Dupont-Draht-Kabel-Linie-Ribbon-Kit/311715750360?hash=item4893b4e1d8:m:mGWlue6bHSXbZjl3sZD9nXw)
You might have to remove the plastic of the plugs though.
Also any standard wire should work. The HP85 is old, so I don't think that there will be any issues with signal integrity because of high speed signals.
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Thanks for the reply and link.
You are right, I could use all sorts of 0.1" and 0.05" pitch conventional cables. But I would have to change a lot of connectors. Most 0.1" connectors have two rows spaced 0.1". These are spaced 0.2" on the board. So quite a bit of mangling would be required, There would be 20 sockets (10 cables) on each HP85 to change to allow for different cabling standards. And then, if anything fails, I have to mangle yet another "donor" unit from another HP85 to fit it, instead of it being a straight swap. I am not that keen to give myself a downstream headache like that yet.
I still feel that, as 2.54mm Flat Flexible Cable sections are very much still available (but in quantity) that I should try that route for now. If I can get a bunch of surplus FCC cables - 20 way, 0.1" pitch and some inches long - or a small reel of the cable itself, I can solve the issue a lot more easily and appropriately. I mean the correct flat-metal conductor type, not stranded, by the way. I can also help out my fellow HP85 enthusiasts with replacement cables.
So thanks, but still looking I am afraid .....
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https://www.aliexpress.com/item/CUSTOMIZED-ORDER-Flat-Flex-ribbon-FFC-cable-4-80-pin-30-800mm-long-pitch-0-5mm/32742592368.html (https://www.aliexpress.com/item/CUSTOMIZED-ORDER-Flat-Flex-ribbon-FFC-cable-4-80-pin-30-800mm-long-pitch-0-5mm/32742592368.html)
They make custom cable including 2.54mm pitch, 30mm-800mm long.