Mac plus copper inside

[marchintosh]

Hi everyone, I bought this Mac Plus in Sweden, and inside I found this copper mask. My idea is that it was installed to prevent interference with other equipment; it was in a lab at the University of Chemistry in Gothenburg.
Do you agree?

 

[Byrd]

Yes it looks like some sort of enhanced RF shielding - see "Tempest" Macs of the same era. Is the mask handmade? It's probably worth a bit noting copper prices nowadays.

 

[obsolete]

That's a very cool piece of history! I think its value is greater intact than scrapped.

 

[David Cook]

Very cool.

 

[cheesestraws]

Yeah that has to be shielding

 

[iantm]

That's pretty sweet, almost a shame it's hidden away in the case.

 

[arroz]

On top of the non-material value of having a very rare piece of Apple history, I found a reference to one that sold for just over 1500 USD. So definitely don’t throw it away nor sell the shield for the copper! https://www.bonhams.com/auction/293...0-x-340-x-330-mm-candes-systems-inc-19861987/

 

[hwertz]

I did some programming work about 10 or 15 years back at a lab that had the whole PC and etc. in a large farrady cage, and ran fiber optics from this box out to the sensors that were actually collecting readings. These were like measuring like EEG stuff, but were presumably very sensitive to noise. I was a little concerned when I fired up this software and saw nasty 60hz noise anyway... they did have those "long tube" style flourescent bulbs and I was not sure how well the farrady cage was blocking thoe noise from those; but it turned out the gain was cranked way up and it was fine once it was set to the range they actually used.

I imagine it would have been a lot less expensive to just farrady cage the computer! Looks like that's what they did!

My recollection is an AM radio would get a fair bit of CRT noise when anywhere near one of these; they may have been shielding against noise from the CRT more than from the motherboard proper. Anyway, that is a neat find!

 

[mikes-macs]

probably belongs in a museum.