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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets.

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Old 26th Nov 2018, 4:09 pm   #21
Al (astral highway)
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Default Re: IC wire-wrapping... who has an old kynar-strippping tool going?

Extraordinary times to have worked in this industry , Ken. I’m fascinated by all aspects of the Cold War, especially technology and defence.

The technique you describe is a brilliant idea. So simple but battle- and storm-force sea-proof !tnat takes some beating !
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Old 26th Nov 2018, 5:48 pm   #22
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Default Re: IC wire-wrapping... who has an old kynar-strippping tool going?

Indeed interesting. One factoid, if I can digress, relates to electronic components under pressure. If you are putting electronics in the sea, there are essentially two approaches. You can use a watertight, pressure proof air filled housing or a watertight pressure balanced housing and fill it with say, an oil. In this letter case the housing can be very light and flexible (maybe like a hose) but the electronic components see the water pressure of up to several thousand psi. Many day-day components are surprisingly tolerant of this, making things easy (well, relatively)

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Old 26th Nov 2018, 7:14 pm   #23
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... but the electronic components see the water pressure of up to several thousand psi. Many day-day components are surprisingly tolerant of this, making things easy (well, relatively)
That's fascinating, too. I was thinking that exposed boards and connectors wouldn't last a month in salt-vapour laden air.

Interesting thought when it comes to the valve era - I've seen 'tropicalised' assemblies for military equipment that had to deal with a similar problem (only heat and humidity rather than salt...) Did they pressurise housings for valve equipment, too?

I know valves were used in power applications until relatively recently.
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Old 26th Nov 2018, 7:47 pm   #24
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Default Re: IC wire-wrapping... who has an old kynar-strippping tool going?

I missed the design side of valves but saw them in use. In underwater kit, they were always in air filled pressure housings. In shipboard kit, they were in shock mounted racks (as is most current kit, I think) with the racks being either liquid (cold walls technique) or air cooled both being closed circuit. Underwater kit had an excellent local heatsink at a constant 4 degrees C. A long time ago now !
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Old 26th Nov 2018, 7:58 pm   #25
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Default Re: IC wire-wrapping... who has an old kynar-strippping tool going?

No exchanges used unstripped wire wrap. The Gardner Denver guns used a cut, strip and wrap bit that would do the whole job. Normally 25swg, 0.5mm, but also bits to do the 21swg, 0.9mm, wire for the pulse and ringer distribution. The wrap was modified as mentioned so a couple of turns of insulation followed by 6-7 turns of wire.

When you have gun wrapped a crossbar rack multiple then you know how to wire wrap! There are 10 shelves, each shelf has four tag blocks, each 14x15 tags, and each tag had an in and out wrap, one shelf had the cable in and out to the adjacent rack.

I have some wire wrap tools from my days at Plessey, but no use for ICs, far too large. The pliers, 81's, had both a wire cutter and a wire stripper for the 25swg wire, work well.

OK Industries used to do a wide range of wire wrap stuff. The thing to look out for is their transparent plastic wire holder, also has a stripper and a plastic cutter. I have had mine since the 70's, used a lot, still works as it did decades ago.
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Old 26th Nov 2018, 10:07 pm   #26
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When you have gun wrapped a crossbar rack multiple then you know how to wire wrap! There are 10 shelves, each shelf has four tag blocks, each 14x15 tags, and each tag had an in and out wrap, one shelf had the cable in and out to the adjacent rack.
Yes, that's quite a trial by fire! I wonder how you did trouble-shooting? There must have been errors here and there, otherwise it seems like asuper-human level of concentration.

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OK Industries used to do a wide range of wire wrap stuff. The thing to look out for is their transparent plastic wire holder, also has a stripper and a plastic cutter. I have had mine since the 70's, used a lot, still works as it did decades ago.

Great, I'll look out for one, that's a pretty solid recommendation!
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Old 26th Nov 2018, 10:33 pm   #27
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Default Re: IC wire-wrapping... who has an old kynar-strippping tool going?

Don't forget the handy "backwards" IC pin number labels for the underside. And "Gas Tight" doesn't mean the insulation was left on and cut through, the enormous pressure on the corners of the pins gave a gas tight joint all by itself.
 
Old 26th Nov 2018, 10:36 pm   #28
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Default Re: IC wire-wrapping... who has an old kynar-strippping tool going?

Just to add to the gallery - the Verospeed Hobby tool, the good stripper and three hand tools. Sorry - still occasionally used for modifying old prototypes.
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Old 26th Nov 2018, 10:49 pm   #29
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I always enjoyed using the tool at the bottom of picture four, a nice relaxed manual method, and it does everything bar cutting the wire.
 
Old 26th Nov 2018, 11:49 pm   #30
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Default Re: IC wire-wrapping... who has an old kynar-strippping tool going?

The stripper looks to be broken on that bottom one......
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Old 27th Nov 2018, 8:27 am   #31
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Default Re: IC wire-wrapping... who has an old kynar-strippping tool going?

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Don't forget the handy "backwards" IC PIN number labels ...

the enormous pressure on the corners of the pins gave a gas tight joint all by itself.
That’s astonishing... I wonder who discovered/devised this technique and how?

And I’m curious about the expression ‘gas-tight’: I’d understand that in a plumbing context , but what were its implications for the resulting finish/boards?

Did it imply that the pins wouldn’t corrode easily from atmospheric moisture?
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Old 27th Nov 2018, 9:14 am   #32
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Default Re: IC wire-wrapping... who has an old kynar-strippping tool going?

According to Wikipedia, Bell labs invented modern wire wrapping after WW2.

https://en.m.wikipedia.org/wiki/Wire_wrap

Not sure if it’s been mentioned but Thorn used the technique in the 1960’s for BW TV’s, much larger wire diameter than used with the wire wrap tools shown in this thread. Instructions were to solder the wire back if the wrap was removed.
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Old 27th Nov 2018, 11:03 am   #33
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Default Re: IC wire-wrapping... who has an old kynar-strippping tool going?

The computer industry made massive use of wire-wrap - but done using automated rigs. This continued well into the era of multi-layer PCBs!

Obviously this was for small volumes of mainframe computers. The argument was that it was quick and easy to make changes, and given the quality issues with early PCBs I suspect it was more reliable.

When I was faced with some DIY wire-wrapping I just made my own tools since the proper ones were rather expensive. I didn't find the special wire hard to strip and my little wrap/unwrap tool was machined from an old pot shaft.

The clever part of wire-wrap seems to be that the properties of the wire is very carefully made so it cleverly ends up very neat as the wrap is finished. I could never work out how it managed to work so well. Ordinary wire doesn't work properly.
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Old 27th Nov 2018, 12:21 pm   #34
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Default Re: IC wire-wrapping... who has an old kynar-strippping tool going?

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The stripper looks to be broken on that bottom one......
Well spotted sir - that was eldest item - supplied by employer when we had to be prepared to work on DEC PDPxx gear.
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Old 27th Nov 2018, 4:53 pm   #35
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The clever part of wire-wrap seems to be that the properties of the wire is very carefully made so it cleverly ends up very neat as the wrap is finished.
And the end of the tool, this squeezes and rolls the wire over the corners of the pins. If you carefully unwind a joint by hand you can feel a little tug on every corner, that's the (gas tight) pressure weld unzipping.
 
Old 27th Nov 2018, 5:12 pm   #36
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Default Re: IC wire-wrapping... who has an old kynar-strippping tool going?

Don't even consider reverse-engineering a fully wire-wrapped board e.g this PDP8 backplane:-
http://dustyoldcomputers.com/pdp8/im...0000261-hp.jpg
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Old 27th Nov 2018, 7:03 pm   #37
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Default Re: IC wire-wrapping... who has an old kynar-strippping tool going?

Also, don't even consider testing such a thing by using pins to push into the IC sockets to test the connectivity.

The Cambridge computer science department was building a research CPU to try out architectures where the hardware itself would enforce access rights in a more complex way than was (still is) traditional.

They built it on wire-wrap boards and after the testing was compete they found that the pins had over-extended every IC socket and the thing was wrecked. I never found out what happened next!
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Old 27th Nov 2018, 8:36 pm   #38
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Don't even consider reverse-engineering a fully wire-wrapped board e.g this PDP8 backplane:-
George...���� .... you didn’t , do you?!
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Old 27th Nov 2018, 8:39 pm   #39
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They built it on wire-wrap boards and after the testing was compete they found that the pins had over-extended every IC socket and the thing was wrecked. I never found out what happened next!
That’s tragic, surreal and comic at the same time! Although not (comic) for the people on the team, I imagine!
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Old 27th Nov 2018, 9:16 pm   #40
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Default Re: IC wire-wrapping... who has an old kynar-strippping tool going?

PYE Telecom built their M87 controller racks and their RLA3 racks this way.
An amazing (for the time - 1983) automated wrapping station did it.

Those who had to make any additions or mods - they had the tool from post#5.

I think I still have mine - if I can find it... One end could unwrap while the other end did new wraps.

Using the "zizzy" unwrapped wire for a new joint again somewhere else would rarely work - far better to find the other end and start again from scratch.

The hand tool was not any good for making the modified wrap of a few turns insulated and then the bare business end.
Only the factory machines did that.

Last edited by Jon_G4MDC; 27th Nov 2018 at 9:22 pm.
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