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| SIMM 'bank clips' for broken plastic retention clips | |
| Posted by: David Cook on 2024-02-06 20:00:21 Yesterday, I posted about some "for parts" Macintosh II/IIx motherboards I recently repaired. Spare Parts Mac II and IIx Successful RestorationsFor some weird reason, I keep buying Macintosh II series boards and computers. Recently, I purchased a sealed AppleService NOS IIx motherboard. I also purchased another lot that consisted of a Macintosh II upgraded to a IIx with the Macintosh II board separate. Upgraded Macintosh II The seller...
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There was one last repair that I hadn't discussed, as I was waiting for a miniature end mill bit to arrive. The Macintosh II has two banks of memory, each consisting of four SIMMs that must be fully populated. Bank A is critical, as it must not be left empty. Unfortunately, Apple used plastic retention tabs to hold the memory in place in the slots. The tabs have a habit of breaking if you aren't careful. In my case, apparently a gorilla last removed the SIMMs from Bank A of the motherboard, breaking six of the eight tabs!  That's right. There is one good tab on one slot, another good tab on another slot, and everything else is broken. There was no way I was going to desolder 120 leads to replace these slots on this motherboard. However, since the entire bank must be populated, perhaps I could quickly make a brace that leveraged all four SIMMs being square with each other and the board. That is, rather than being a single SIMM clip, it is a 'bank clip'. As you can see below, it works beautifully.  This is nothing more than a 10 mm x 10 mm plastic bar (kitchen cutting board material) with slits cut in it every 10 mm. The slits are 1.3 mm thick with a 5 mm depth.  The SIMMs really are firmly in place. The SIMM slot itself retains the SIMMs in all directions. The original retaintion tabs only prevented the SIMM from rotating and I guess acted a little like spring clamps to hold the SIMM steady. The slits in the bank clip now perform that duty. The memory SIMMs are almost friction fit in the bank clip's slits, with any slight rotation of any SIMM (due to slit tolerance) causing the mating parts to grab even more. This is not a complicated design. I imagine it could be 3D printed. (And, perhaps someone else thought of this idea years ago.) The critical dimensions are: 1. The thickness of the slits. Too wide and the memory SIMMs can independently rotate enough to be loose. 2. The spacing between slits. The bank won't press down if an slit is out of alignment. 3. The squareness of the slits to each other I used a hobbyist milling machine with a homemade caliper DRO to make the precision cuts.  Here is a close-up showing that there is nothing more fancy to this than a bunch of slits in a bar of plastic. Aside: I broke two bits before realizing I needed to crank up the RPMs (3000) and make passes of less than 0.5 mm depth of cut with such a tiny end mill.  This was just a 'make do' prototype. I think a neater solution would be to cut slits in a piece of FR-4 circuit board substrate (without copper). It is a tough and rigid material. You'd end up with a thinner brace. - David | |
| Posted by: zigzagjoe on 2024-02-06 21:10:16 I did something similar for my SE/30s that have suffered some attrition over the years. I don't seem to have any decent pictures handy... these are the best I've got. I'm not sure if they'd be sturdy enough for the damage yours have suffered - that's impressively bad - but for a clip here and there, or a single simm with both broken, they've worked just fine. Model attached.    | |
| Posted by: joshc on 2024-02-06 22:26:50 These are both far better than the rubber band / hair band solution I’ve used before. Nice | |
Posted by: jmacz on 2024-02-06 22:57:02I used a hobbyist milling machine with a homemade caliper DRO to make the precision cuts. Those mills are nice, especially since they are small. I have a CNC converted one in my garage. I was eyeballing my SE/30 this evening (one slot has broken clips) and thinking of the same general design. But will probably use my resin printer instead of my mill. Pretty cool though, thanks for sharing! | |
| Posted by: s_pupp on 2024-02-07 07:24:19 Well done, and thanks for the detailed pics! | |
| Posted by: LaPorta on 2024-02-07 07:47:29 I’m just utterly impressed by all of you who do these things. | |
Posted by: David Cook on 2024-02-08 07:05:25I did something similar for my SE/30s that have suffered some attrition over the years. I don't seem to have any decent pictures handy... these are the best I've got. I'm not sure if they'd be sturdy enough for the damage yours have suffered - that's impressively bad - but for a clip here and there, or a single simm with both broken, they've worked just fine. Model attached.Your solution is a lot more elegant, not only in size, but also it seems more tolerant of different memory PCB thicknesses. Ideally, imagine a design similar to yours, but made out of steel and featuring springy clips. It would fit on top and clip onto the memory IC to act like a heat sink as well as a retainer. Sort of like this but shorter and connected together. Alternatively, I considered a tiny clamp with a set screw just to replace the missing retention tab. | |
Posted by: David Cook on 2024-02-18 18:09:25 Has anyone ever seen a "SIMM Removal Tool" #076-8354? | |
| Posted by: RepairManiac on 2024-04-22 10:14:44 I recreated the image with actual tools 😁 Yes, we actually used the SIMM Tool since breaking the customer's clip(s) was a big no-no. These retaining clips were fragile even when NEW!!!  | |
| Posted by: obsolete on 2024-04-22 10:51:38 Wow! I would love to get one of those tools to design a replica for 3D printing. | |
Posted by: David Cook on 2024-04-23 06:52:54I recreated the image with actual tools 😁 What a fantastic picture! I'm envious of your Mac tool collection. | |
| Posted by: olePigeon on 2024-04-23 12:02:08 I also have a SIMM removal tool, but it's of a different design. | |
Posted by: joshc on 2024-04-23 12:12:10I recreated the image with actual tools 😁You might be the first person I’ve come across that has the Apple CRT discharge tool! That’s rather neat. | |
| Posted by: David Cook on 2024-05-01 19:52:21 Thanks to an eBay link from @RepairManiac, I was able to purchase one of the SIMM removal tools. Here are some close-up pictures.     It is made out of a really high-quality plastic. The grip feels heavy, though. Weighted with a metal insert? The adjustment slide with the single screw lacks notches, so it isn't very accurate when choosing the memory width of 30, 72, etc. At first, I thought that was to allow you to adjust the width based on the PCB. But, really it should be fixed to the width of the latches on the memory slot, which should be fairly precise. No big deal. The first step of guiding it onto the top of the memory stick is a little awkward. But after that it slides down and releases the latches like butter! No 'clicking' and no pressure. It is surprisingly amazing. Maybe I'm being too optimistic, but it seems like this would make broken plastic latches a thing of the past. - David | |
| Posted by: RepairManiac on 2024-05-02 09:26:51 @David Cook That's awesome and it was NEW too where mine is heavily used. It does feel heavy - weighs 2.5 oz. I just used it again, for the first time in decades, on a Mac SE/30 and YES it does work like butter once an adjustment was made! Also used it to remove the ROM SIMM too. It was Apple's answer to technicians complaining of breaking those fragile clips on early Macs. Doesn't look like it was a required tool, but we had one on every Mac bench. Sadly I can only find the one now. If anyone else is interested, someone *not me* just listed another one on eBay - Search for Amp 821987-02 | |
Posted by: obsolete on 2024-05-02 11:26:09If anyone else is interested, someone *not me* just listed another one on eBay - Search for Amp 821987-02 
AMP ANTI STATIC # 822036-1 # 821987-02 VINTAGE USED (VGC) | eBayFind many great new & used options and get the best deals for AMP ANTI STATIC # 822036-1 # 821987-02 VINTAGE USED (VGC) at the best online prices at eBay! Free shipping for many products!
www.ebay.com
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| Posted by: olePigeon on 2024-05-02 14:32:30 @David Cook Wow, yours is fancy and adjustable. Mine is only for 30 pin SIMMs, nothing else. | |
Posted by: davewongillies on 2024-05-02 15:26:39Yeah sorry, that was me Wow! I would love to get one of those tools to design a replica for 3D printing.I'd be happy to loan you mine (once I get it) for you to make a replica of it as long as the model gets shared freely | |
Posted by: obsolete on 2024-05-02 15:40:23Yeah sorry, that was meAbsolutely. I will post the model here and Thingiverse, as well as the original design files for anyone who may want to make modifications. I am confident that this is well within my 3D modeling capabilities, and I should be able to turn it around in a week or less. I am also happy to send you a deposit equal to or greater than the value of the tool while it's in my possession. Send me a PM when you're ready to loan it out. Thank you! | |
| Posted by: obsolete on 2024-06-13 09:00:45 Got one of my own! https://www.arcade-electronics.com/AMP-821987-2-SIMM-Extractor-Removal-Tool-p/amp-821987-2.htm Ordered yesterday and it shipped today, so I assume it's legit. Will report back. | |
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