Recreation of RFI shields for compact Macs - 128K, 512K, Plus, SE and SE/30

fehervaria

Tinkerer
Sep 23, 2021
153
158
43
47
North Germany
As a side work of my rebuilding of the Macintosh 512K, I ended up recreating the RFI shields for the 512K.
Then, I thought I should do it for all early compact Macs, like the 128K, 512K, Plus and SE, SE/30.
Macintosh Plus - RFI Shield 805-5047-04.jpeg

I have one good condition RFI shied for the Mac Plus - so I started with the recreation with that RFI shield.
First, I did a hand-drawn copy of the shield, scanned it, and recreated it in Pages with simple shapes like circles and lines. The mouse connector's (D-Sub 9) outer shape was the most complicated shape. From that, I quickly created the Floppy connector shape, and of course, the SCSI D-Sub 25 was also "easy".

The original sheets I own are made of a 0.2 mm aluminium sheet. I was lucky; I could order a 50x50cm 0.2mm thin aluminium sheet board.
AluSheet.jpg
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ScreenShot 2023-10-15 - 16.18.55.png

When it arrived, I cut a roughly identical size from the complete (50x50 cm).
IMG_6533.jpeg
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IMG_6535.jpeg
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Then, I used a cutter and a tool to cut out the round and straight lines from the metal.
You see the first prototype in the pictures - later, I studied how to cut this thin aluminium sheet with the knife.
The good point about working with this thin sheet is that the aluminium is flexible enough to be able to correct it - make it look nicer - if you make mistakes or imprecisely cut the edges.
IMG_6548.jpeg

I used this tool from the OBI hardware store to cut the holes and the round edges of the connectors. This is a cheap belt-hole puncher, but it worked well!

IMG_6541.jpeg

Finally, I cut and fixed the cardboard to the backside to protect the logic board from getting touched by the aluminium RFI shield.
IMG_6542.jpeg
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You can download the 128K & 512K, the 512K, the Plus and the SE & SE/30 shield drawings:
Macintosh 128K & 512K - RFI Shield 805-0577 REV D.pdf
Macintosh 512K - RFI Shield 805-0583 REV B.pdf
Macintosh Plus - RFI Shield 805-5047-04.pdf
Macintosh SE & SE/30 - RFI Shield 805-5060-E.pdf
 

Attachments

  • Macintosh 128K & 512K - RFI Shield 805-0577 REV D.pdf
    22 KB · Views: 35
  • Macintosh 512K - RFI Shield 805-0583 REV B.pdf
    23.6 KB · Views: 53
  • Macintosh Plus - RFI Shield 805-5047-04.pdf
    23.1 KB · Views: 38
  • Macintosh SE & SE:30 - RFI Shield 805-5060-E.pdf
    23.7 KB · Views: 46

croissantking

New Tinkerer
Feb 7, 2023
68
24
8
As a side work of my rebuilding of the Macintosh 512K, I ended up recreating the RFI shields for the 512K.
Then, I thought I should do it for all early compact Macs, like the 128K, 512K, Plus and SE, SE/30.
View attachment 13832
I have one good condition RFI shied for the Mac Plus - so I started with the recreation with that RFI shield.
First, I did a hand-drawn copy of the shield, scanned it, and recreated it in Pages with simple shapes like circles and lines. The mouse connector's (D-Sub 9) outer shape was the most complicated shape. From that, I quickly created the Floppy connector shape, and of course, the SCSI D-Sub 25 was also "easy".

The original sheets I own are made of a 0.2 mm aluminium sheet. I was lucky; I could order a 50x50cm 0.2mm thin aluminium sheet board.
View attachment 13833View attachment 13834View attachment 13839

View attachment 13846
When it arrived, I cut a roughly identical size from the complete (50x50 cm).
View attachment 13835View attachment 13836View attachment 13837View attachment 13838View attachment 13840View attachment 13841
Then, I used a cutter and a tool to cut out the round and straight lines from the metal.
You see the first prototype in the pictures - later, I studied how to cut this thin aluminium sheet with the knife.
The good point about working with this thin sheet is that the aluminium is flexible enough to be able to correct it - make it look nicer - if you make mistakes or imprecisely cut the edges.
View attachment 13845
I used this tool from the OBI hardware store to cut the holes and the round edges of the connectors. This is a cheap belt-hole puncher, but it worked well!

View attachment 13842
Finally, I cut and fixed the cardboard to the backside to protect the logic board from getting touched by the aluminium RFI shield.
View attachment 13843View attachment 13844

You can download the 128K & 512K, the 512K, the Plus and the SE & SE/30 shield drawings:
Macintosh 128K & 512K - RFI Shield 805-0577 REV D.pdf
Macintosh 512K - RFI Shield 805-0583 REV B.pdf
Macintosh Plus - RFI Shield 805-5047-04.pdf
Macintosh SE & SE/30 - RFI Shield 805-5060-E.pdf
Nice work!

How crucial is it to have? One of my SE/30s is missing its shield.
 

fehervaria

Tinkerer
Sep 23, 2021
153
158
43
47
North Germany
Thank you, @CroissantKing.
As I am not an expert of high-frequency hardware engineering, I can not fully answer your question.
I was thinking on the way: if Apple decided to add different kind of RFI/EMI shields, and possible to follow the evolution of these shields, probably they are important.
Rough understanding the RFI/EMI shields functionality, it needs for the reliability of the Mac. It is CRT Tube with high voltage, high frequencies in the same cage as the analog, and the logic boards, therefore protecting the logic board from "other" external disturbing sources.
But this is only my personal logic - without a real engineering background.

I would recreate the 805-5060-E shied for the SE/30.
 

François

Tinkerer
Aug 9, 2022
79
37
18
France
Shielding (computer) electronics seems to be something that was needed back in the eighties? (if you ever took apart an Atari ST, the motherboard is entirely enclosed in a rigid steel shield)

Maybe computers back then were more sensitive to external interference, or it was the other way around: shielding was required by law as to no disrupt nearby equipment?
 

Patrick

Tinkerer
Oct 26, 2021
434
1
223
43
shielding was required by law
that was my understanding. It was more about protecting other equipment than protecting the computer itself. But I do NOT know for sure.

However, some computers require it to even turn on. Because its used as ground. I think maybe the color classic ? Adrian Black found this out the hard way as he tends to just throw them away.....
 
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Dogmander

New Tinkerer
May 9, 2023
10
4
3
Ohio, USA
that was my understanding. It was more about protecting other equipment than protecting the computer itself. But I do NOT know for sure.

However, some computers require it to even turn on. Because its used as ground. I think maybe the color classic ? Adrian Black found this out the hard way as he tends to just throw them away.....
He had audio issues without the shield with his Color Classic, so it definitely has some significance.
I do agree about throwing them away is bad, it might just be better to clean up the rusty one and cut away any bad bits. Better a lacky shield than no shield at all.
 
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fehervaria

Tinkerer
Sep 23, 2021
153
158
43
47
North Germany
It had a reason - any - why Apple decided to design & manufacture this complex part. It is possible to see, each has an evolution, development cycles.
AND: it is part of the computers we restore and enjoy using them. This is "maybe" not relevant for functionality - but as we see, sometimes yes - but part of the full restoration project.
Many times we found strongly damaged, battery-acid-eaten RFI-shields - for those replacements I've thought the RFI-Shield sketches are good help.
 
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RetroViator

Tinkerer
Oct 30, 2021
82
101
33
retroviator.com
I’m currently working on an LC II, and noticed the shield has tabs that contact pads or connectors on the bottom of the logic board.
 

Attachments

  • IMG_8190.jpeg
    IMG_8190.jpeg
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