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Vintage Computers Any vintage computer systems, calculators, video games etc., but with an emphasis on 1980s and earlier equipment. |
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14th Dec 2020, 10:09 am | #1 |
Pentode
Join Date: Sep 2011
Location: Coventry, West Midlands, UK.
Posts: 211
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Power lead deterioration
I dug out my old laptop to use the car adaptor for something else, and found this. It's not quite old enough to be vintage yet, but it might not last long enough to become vintage! the company that made it (EASi) only goes back 35 years. The insulation on the curly lead has gone soft throughout its length.
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14th Dec 2020, 10:19 am | #2 |
Dekatron
Join Date: Aug 2003
Location: near Reading (and sometimes Torquay)
Posts: 3,086
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Re: Power lead deterioration
There does seem to be something quite specific that goes wrong with certain plastics that I would not consider to be all that old.
One example I have encountered was an NOS, packed in sealed bag, Racal Morse key. On removal from its sealed packing it looked brand new and absolutely fine. But after not very long the outer cable insulation started to break up into small pieces - while remaining quite soft and plastic. The inner wiring was fine. I have seen this effect on other cables too, possibly 30 to 40 years old. |
14th Dec 2020, 10:57 am | #3 |
Octode
Join Date: May 2018
Location: Northampton, Northamptonshire, UK.
Posts: 1,395
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Re: Power lead deterioration
Yes, you would normally expect plastic cable insulation to last much longer than older rubber-insulated ones - particularly when exposed to heat
(Although normal PVC isn't too great when heated a bit, and have seen some issues on mains-wiring where it's heated up and insulation has failed / reacted with copper). There was also apparently an issue with some early (foam dielectric?) co-ax cables that their loss could increase with age due to reaction of chemicals in the foam on the copper. Most problems I've seen with consumer electronics, has been reaction between the polystyrene packaging and the cable's outer insulation. But I have seen a cable react with the case lid on an old BBC computer when cable had been on the top for years - but caused much more damage to lid than to the cable. I did once use a CPC Pro-Power multiway cable - chosen because it was much more flexible than others - in a PowerCon connector. And found after a few years, the neoprene? pressure gland had reacted with the cable's outer insulation making it go from grey to brown and start to break up exposing the wires inside (luckily insulation remained OK on these, and it was all 12V) |
14th Dec 2020, 10:12 pm | #4 |
Octode
Join Date: Apr 2018
Location: Newbury, Berkshire, UK.
Posts: 1,287
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Re: Power lead deterioration
Theres a problem with old cables where the plasticiser used to soften pvc can leach out of the cable, causing the pvc to degrade and sometimes reacting with the copper to make "green goo". Owners of old computers from the 70s/80s stored for long periods often find marks on the case where cables wrapped around or packed on top of computers can melt the plastic. I believe modern pvc uses different formulations so may not suffer from this problem.
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14th Dec 2020, 10:46 pm | #5 |
Dekatron
Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 11,485
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Re: Power lead deterioration
I have a Yaesu FT90R mobile radio from the mid nineties which I use seasonally. When I put it away last year the slightly rubberised microphone lead was fine, but when I got it out this year about 2-3 inches of the rubber sheathing at the microphone end had just disintegrated. The PVC insulation of the inner wires was fine. Fortunately, it is still possible to buy replacement cables.
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14th Dec 2020, 11:26 pm | #6 |
Nonode
Join Date: Jun 2008
Location: Coningsby, Lincolnshire, UK.
Posts: 2,814
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Re: Power lead deterioration
Apple like using insulation on their cables that falls to bits like that too! I’ve got 2 MacBook Pro chargers that are falling to bits, chargers still work perfectly though, so I might just patch it with heatshrink.
Regards Lloyd |
14th Dec 2020, 11:46 pm | #7 |
Octode
Join Date: Mar 2019
Location: Barry, Vale of Glamorgan, Wales, UK.
Posts: 1,362
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Re: Power lead deterioration
This has happened to my Guitar Hero foot pedal and more disconcertingly to the remove control lead on my Mum's Bath Lift - both only around 10-15 years old.
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15th Dec 2020, 12:45 am | #8 |
Dekatron
Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 11,485
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Re: Power lead deterioration
This almost did for the DC cable on my ZX81 PSU. Although I no longer have the outer cardboard sleeve I still have the two polystyrene shell halves and for years I kept everything protected in that, but then on one of my periodic checks I found the cable had spot-welded itself to the polystyrene. I was able to peel it it off with great care and now the only thing kept in the polystyrene shell is the manual.
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15th Dec 2020, 12:48 am | #9 |
Dekatron
Join Date: Aug 2016
Location: Colchester, Essex, UK.
Posts: 4,081
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Re: Power lead deterioration
Perhaps less known is an interaction between PVC and ABS. (might be significant here as related to an in-car adaptor)
PVC insulation pulled tight against ABS plastic in environments with unstable temperatures can leave a 'melted' mark in the ABS- so god knows what it does to the PVC- but it can't be good. Dave |
15th Dec 2020, 1:43 pm | #10 | |
Dekatron
Join Date: Aug 2013
Location: Wigan, Greater Manchester, UK.
Posts: 9,428
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Re: Power lead deterioration
Quote:
Edit. Perhaps what we both mean by early is very different.
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Frank |
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15th Dec 2020, 6:00 pm | #11 |
Dekatron
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 13,953
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Re: Power lead deterioration
Re. post #2: I've had the same happen with the cables on "Clansman" military-radio handsets. I guess there was some sort of degradation which could not have been forseen 40+ years ago when the kit was originally specified.
I also had the lead on a new-in-box late-1980s Microsoft (Micerosoft?) serial-mouse - the original two-button type with a moulded-on 9-pin "D" plug - turn out to be stiff and brittle when unboxed. |
15th Dec 2020, 7:22 pm | #12 |
Pentode
Join Date: Jun 2012
Location: Bristol, UK.
Posts: 115
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Re: Power lead deterioration
This ties in with the deterioration of plastic foams and corrosion of IC pins in conductive foam; these wonder-materials self destruct.
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15th Dec 2020, 7:33 pm | #13 |
Dekatron
Join Date: Jun 2013
Location: East Sussex, UK.
Posts: 3,315
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Re: Power lead deterioration
My iPad original leads all have insulation problems at the device end but never at the USB end which is always plugged into the charger. Now have about 6 inches of heat shrink sleeving over the inner screening. Must be due to handling that causes the destruction of the original soft rubber coating.
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15th Dec 2020, 7:50 pm | #14 |
Dekatron
Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 11,485
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Re: Power lead deterioration
In the case of the Yaesu microphone I mentioned in #5, the only part of the cable outer which crumbled was the section nearest the microphone. Obviously that part is always going to suffer the most of being bent in all directions but it is also the only section likely to come into contact with my fingers quite often, so there may be something in what you say.
No wonder conservationists always wear gloves. |
15th Dec 2020, 8:43 pm | #15 | |
Dekatron
Join Date: Nov 2011
Location: Surrey, UK.
Posts: 4,385
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Re: Power lead deterioration
Quote:
Colin |
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16th Dec 2020, 3:03 am | #16 |
Heptode
Join Date: May 2010
Location: Warminster, Wiltshire, UK.
Posts: 682
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Re: Power lead deterioration
As mentioned in post 4 reference the green goo .
It’s quite common in mains wiring especially cable manufactured in the late 60s . It’s often only minor but on a couple occasions I have seen it so bad it’s been running down the walls out of sockets and switches. I even had one occasion it completely filled a MCB with the goo . Only option was to rewire. The problem isn’t limited to one brand of cable. Andy
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I bet that car doesn't have a suppressor. |
20th Dec 2020, 1:22 am | #17 | ||
Octode
Join Date: May 2018
Location: Northampton, Northamptonshire, UK.
Posts: 1,395
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Re: Power lead deterioration
Quote:
I had first read about it in a 1990's? Television (Servicing) magazine And I presumed it was an issue with (gas-injected?) foam dielectrics, and they'd only started using these in later co-ax cables as an alternative to semi-air spaced, to keep losses down from solid dielectric types. So this may have resulted in foam types having a bad reputation and falling out of favour. But improved types made a comeback when used for satellite etc. dishes as less issues with reflections from impedance discontinuities if bent too sharply (as well as not acting as a water pipe once water got in one end, ruining the cable and not too good for equipment on the other end !) So I've always gone for CX-100 foam dielectric rather than CT-100 cable. |
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20th Dec 2020, 1:35 am | #18 | |
Octode
Join Date: May 2018
Location: Northampton, Northamptonshire, UK.
Posts: 1,395
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Re: Power lead deterioration
Quote:
Usually, luckily only affecting the pin-leg rather than the shoulders (although I've seen these go as well). So can often be repaired, by either carefully soldering IC into an extra turned-pin etc. 'carrier' socket, or by pushing some suitable gauge solid TCW into socket and soldering to IC's pins shoulders. And maybe worth doing on more valuable ones, although when I was trying to do it an old (1977?) more uncommon 54LS157 the other day, I was unusually having trouble even getting LMP tin/lead/silver solder to stick to the shoulder, despite scraping it a bit first. It seemed like trying to solder to steel, without plating, and I nearly had to dig out some Aluminium solder that's good for materials like that (before normal solder on top, to give a brighter finish) |
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21st Dec 2020, 12:48 am | #19 |
Dekatron
Join Date: Apr 2012
Location: Worksop, Nottinghamshire, UK.
Posts: 5,549
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Re: Power lead deterioration
I have also discovered leg rot foam too. It was a few years ago.
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21st Dec 2020, 1:06 pm | #20 |
Nonode
Join Date: May 2007
Location: Redruth, Cornwall, UK.
Posts: 2,562
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Re: Power lead deterioration
Hi.
I wonder if it has anything to do with bacteria affecting some plastics. https://www.euronews.com/living/2020...for-scientists Regards, Symon |