Is it ok to do away with the Macintosh Plus bottom shield?

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IIeBoy's picture
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Is it ok to do away with the Macintosh Plus bottom shield?

The flimsy metal and plastic shield at bottom of the logic board in a machine I'm refurbishing is partly corroded away. How necessary is this shield? Can I simply dispose of it? The plastic case isn't conductive so I'm not sure of the need.

Thank you .

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Do you "need" it? ...

Do you "need" it? ... No.  It was intended as an RFI shield. 

The Computer will work fine without it but you might get Radio interfenrece on your AM broadcast radio. :-O

It also serves as a bit of protection for the PCB and the bottom case which might be coated with a conductive layer.

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What's an AM radio? Is that
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What's an AM radio? Is that
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What's an AM radio? Is that
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Sorry about the posts above.

Sorry about the posts above. The server seemed to be having issues. Anyway, aside from my joke of "what's AM radio", I wrote that I'll just cut the back corroded part off but retain the base that goes under the PCB .Thanks!

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If you are obsessesed with

If you are obsessesed with electromagnetic compatibility, you could remake a badly corroded bottom shield with copper foil tape:

 

It's overkill in terms of electromagnetic interference but the shield is important to ensure the digital board doesn't short to the conductive paint on the case.

I will remark that I once got a Mac Plus and turned it on. It worked for a minute until I heard a loud "bang" so I pulled the plug and opened the case. The piece of insulation on the analog board (not the digital board) was missing, and there was a big burned spot on the analog board. Evidently it had shorted to the conductive case material. I replaced some faulty-looking components, turned on the machine, and then part of it caught on fire. I replaced even more on the analog board... complete capacitor replacement and much of the silicon! Still not working. It made the "flupping" noise and has not yet been fixed after some time...

The digital board is much more tame and is held further from the case than the analog board, but it goes to show that you never know what might touch if you were to, for example, shake a Mac without the electrical insulation provided by that sheet. So I'd try and put it in if you can.

 

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