Do I need RF shielding?

[TweedyF]

Just opening up an old Mac and discovered its metallic shielding is completely missing.

Having done a quick bit of forum searching and googling, I'm still unsure:

• Do I need it, either for my or the computer's welfare?
  
• If I do, does anyone have any recs for the foil I should buy to cut out new shielding panels?
  

 

[Cory5412]

What Mac is this?

This is highly context-sensitive, but it would be better if you had it.

An old TV crashed entire town's broadband every day for more than a year - CNET

Strictly speaking, if the environment is basically fine, low density, you don't have magnets nearby, you don't need it. It shouldn't be a risk to your health or the computer's, but lots of newer things are built not accounting for vintage tech needs. I, for example, have an IKEA bluetooth speaker that creates obvious distortion for CRTs when it's nearby.

The biggest thing I'd watch out for, and this might be something you can test for, is whether or not the lack of sheilding causes issues for, like, floppy diskettes stored nearby.

 

[TweedyF]

Thanks @Cory5412 - this is a Color Classic

 

[cheesestraws]

If it's something with a CRT in it, it's probably a good idea.  It won't harm you, and it probably won't damage your other computers, but it's a good way to introduce gremlins into life, or worse, other people's lives.

 

[Chopsticks]

usually its just used for EMI compliance with different countries having different levels of EMI suppression required for a product to be sold commercially.
in theory it could cause some interference issues due to the cut and logic board proximity to each other in the coloraturas classic but unless you get actual display issues it isn't actually going to cause any damage so you can run the machine without it if is missing.

Some older devices relied on the shielding for the grounding but the color classic is grounded through its internal edge connector cable harness anyway so its not a issue in this situation.

also without the internal shielding there is a potential for the color classic to cause interference to other devices or other devices to cause interference to the color classic due to RF emissions.

In short unless you run into any issues it is electrically safe to operate the color classic without its internal shielding. please not however that this isn't universal advice for all electronic devices, some will not run at all without its shielding and some decided will have nothing but issues without its shielding, so its always best to check with us/others if you run into this issue again with another device

 

[Dog Cow]

Earlier this summer I placed an AM/FM radio with its antenna extended, right next to my Mac 512K or Mac Plus, and at some high-end frequency I could hear every action of the Mac. I could hear loops, disk access, and so many other noises.

I tried the same thing with the Power Mac G3 and could hear almost nothing. I think that radiation is a function of not only shielding, but also miniaturization of components.

 

[cheesestraws]

I tried the same thing with the Power Mac G3 and could hear almost nothing. I think that radiation is a function of not only shielding, but also miniaturization of components.

Also, frequency of operation of the components.  I would expect interference generated by a G3 to be significantly higher-frequency than from an older machine, because most of the bits are running faster.  I remember that (according to Johan Johansson, anyway) when the IBM 1401 was introduced to Iceland, they used to play tunes on it by accessing memory at the right frequencies and tuning an AM radio beside it.  I doubt that would work any more unless you had a multi-gigahertz AM radio...

 

[TweedyF]

Thanks again everyone! I'll probably try to construct a shielding replacement, but glad to know it's not a priority.

 

[rplacd]

FWIW, I don't think Classics/Classic IIs have ever had foil shielding.

 

[TweedyF]

From what I've been able to tell, there is shielding on the lower part of the case. It covers the bottom and the sides up to about where the vents end and the analog components begin. (Oddly enough?)

You can see what I'm talking about (around the sides) here and (along the bottom) here. The one I picked up has none of that.