Products > Test Equipment
ABS plastic degradation (brittle) - HP34401A (circa 1992)
(1/7) > >>
rfdes:

I recently was in the process of removing the cabinet from my HP34401A and without any effort the ABS plastic handle snapped in half.  In an attempt to repair the handle with epoxy, the handle snapped in two additional places.  It was obvious that the ABS plastic had deteriorated to the point where it became as brittle as a potatoe chip.  I understand that UV can be dangerous to ABS plastic.  However, my multimeter has been stored in a clean, cool location for its entire life, so I am stumped as to how the plastic died the way it did.  Has anyone experienced this issue and if so is there an explanation?

thanks
TheDefpom:
If it has been under fluorescent lighting that would possibly cause it, as fluorescent lights generate low levels of UV, especially if the polycarbonate cover that is normally used with them is missing as the covers block most of the UV.

james_s:
I had this happen with a TDS3000 scope. I have no idea what happened to it as I was not the original owner, but the plastic deteriorated until it was crumbling.
tooki:
While I'm sure light exposure accelerates the process, it's just an unfortunate decomposition process of some ABS formulations. IIRC it even affects products that are new old stock in the box.

I'm a bit of a vintage computer nerd, and one huge problem for collectors is Macs from around 1990 through the mid-late 90s: the plastic is becoming, as you so aptly put it, as brittle as potato chips. So people buy a lovely all-in-one from 1994 on eBay, then the seller ships it to them, and what arrives is a box of plastic bits with a motherboard and CRT sitting in it. Even if packaged correctly (which, frankly, is almost never the case...), the weight of the CRT alone is enough to crack the plastic under normal handling, never mind the torture caused by UPS.

What's interesting -- and what made me click the thread -- is that 1992 is right when something changed in the ABS formulation that causes it to embrittle far more than earlier formulations. Macs from earlier than that, like an original 1984 Mac or a Mac Plus (1986-1990) are holding up just fine, with only slight embrittlement, while the 1990s Macs are now extraordinarily fragile. Some speculate that it's due to changes in flame retardant additives, but I don't think anyone outside of the plastics industry really knows.

(All plastic Macs from the iMac in 1998 onward are made of polycarbonate, not ABS, and so will presumably have very different aging effects than their ABS predecessors.)
tooki:
http://dtc-wsuv.org/wp/ell/2014/01/19/we-lost-four-computers/

This shows the damage of one of the worst-affected models, after shipping (with no damage to the box). But this was 8 years ago, when that machine was 20 years old. At nearly 30 now, they look even worse after shipping.

(Sorry to focus on the Macs, it's just to show that it's something that affected a ton of products from that era, all of which used top-quality materials.)
Navigation
Message Index
Next page
There was an error while thanking
Thanking...

Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod