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A word of caution about storage and cables...

S

SiliconClassics

Experienced Member
Joined
Aug 21, 2009
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148
Location
Chapel Hill, NC
A strange phenomena has occurred with a couple of my keyboards and a Wacom tablet during storage. In spots where the cable touched the plastic case, indentations were made. This seems to have happened during the course of a year or more.

It seems to be the result of some kind of slow chemical reaction between the rubber cable and the plastic. Thinking about how many vintage devices I've stored with the cables lazily wrapped around them is starting to make me nervous :(

Has anyone else seen this?

Dell Keyboard Cable Marks.jpg
 
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Yes, I've seen that before.

I have an old Microanta VOM that has dozens of those grooves on the edges of the case from wrapping the probe cables around it.

OTOH, I have not seen it on keyboards like you have.

Funny.

smp

EDIT: Hey, it's my 1000th post!
 
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Hmm never seen that. Are the cables sticky? Were they stored someplace where it got really hot like an attic?
 
I've had this exact thing happen to quite a few of my vintage joysticks. Hadn't seen it on any keyboards (yet?). I've taken to creating a loose circle with the cable and ensuring it doesn't touch the case during storage.
 
Is that a Dell AT101(W)? Most of the ones I've seen or used have those kinds of marks on the case.

Same thing happens when an item is left in its original styrofoam packaging for years. The cable "melts" the styrofoam and gets stuck to it.
 
Might be plasticers from the cables

Might be plasticers from the cables

Nowadays cables are (supposed to be, looking at you, China..) solely made of TPE (thermoplastic elastomers) which contain no (volatile) plasticizers.
But the common material before was plasticized PVC, as the PVC is is also fire retardant by itself and suitable TPE's were not really available until in the 80's.

Yes, commonly used PVC (or vinyl, as you use to call it) plasticizers will readily diffuse / migrate into ABS, and soften/degrade that material.
It might lead to microcrazing too, making the case locally *brittle* - that is a nasty one too, as you might not see it.
The most commonly used plasticizers in old cabling can be expected to be several kinds of phtalates.

Here is a somewhat relevant article on it, although focusing on medical packaging

http://www.qmed.com/mpmn/article/know-your-plasticizers-new-study-plasticizer-migration
 
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That must be it, Jorg. The plasticizers in the cable are literally melting the plastic.

vwestlife: Yes, it's a Dell PS/2 keyboard, model SK-8000. The cable itself looks fine, only the casing has been damaged where contact occurred. Temperatures were never extreme.

We need to be careful how we store our vintage devices. Cables should be coiled and wrapped if possible to prevent contact with plastic components. Easier said than done when you've got as much stuff as many of us do.
 
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