My solution to RAM module wobble

Discussions about Sinclair ZX80 and ZX81 Hardware
Neurogate
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Re: My solution to RAM module wobble

Post by Neurogate »

sboisvert wrote: Sun Aug 22, 2021 2:42 am I've always wondered if that recessed slot at the bottom of the case next to the edge connector was meant to attach peripherals more securely (with screws) to avoid any wobble.
I think it is really possible to make 3D printed something like "dock station" for RAM pack, which will be connected to ZX81 by two screws. Of course it will be also not authentic solutions
Sinclair ZX81, Sinclair QL, Sinclair ZX Spectrum +2, Atari 130XE, Commodore 64C, Commodore C128, Yamaha YIS503IIIR MSX2 & etc
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1024MAK
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Re: My solution to RAM module wobble

Post by 1024MAK »

Neurogate wrote: Wed Sep 01, 2021 12:05 pm Next level - Raspberry Pi inside real ZX81 case, but I do not sure, that it will be Sinclair ZX81
That’s heresy :shock:

Mark
ZX81 Variations
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ZX81 Video Transistor Buffer Amp

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Neurogate
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Re: My solution to RAM module wobble

Post by Neurogate »

1024MAK wrote: Wed Sep 01, 2021 12:46 pm That’s heresy :shock:

Mark
Sure, I 100% agree with you. Raspberry Pi inside real ZX81 case - it was just a joke, maybe some stupid joke. For me is better to work with original hardware, if it is possible.
Sinclair ZX81, Sinclair QL, Sinclair ZX Spectrum +2, Atari 130XE, Commodore 64C, Commodore C128, Yamaha YIS503IIIR MSX2 & etc
Neurogate
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Joined: Tue Aug 31, 2021 6:46 pm

Re: My solution to RAM module wobble

Post by Neurogate »

Just for illustration of simple solution with a double sided scotch :)
Of course is it not ideal solution and not so elegant as offered by Tackemon, but it's really simple and used by me.
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Sinclair ZX81, Sinclair QL, Sinclair ZX Spectrum +2, Atari 130XE, Commodore 64C, Commodore C128, Yamaha YIS503IIIR MSX2 & etc
TomboCZ
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Re: My solution to RAM module wobble

Post by TomboCZ »

This is a genuinely nice and elegant solution. Could you please upload your model to www.thingiverse.com? Thanks a lot.
David G
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Re: My solution to RAM module wobble

Post by David G »

Looks very nice. Was the STL ever posted?
Tackemon wrote: Fri Aug 20, 2021 10:45 pm...ran into some *serious* wobble
...
So I 3D printed little shim/wedge/spacer, whatever you want to call it that puts some pressure on the bottom of the connector. Surprisingly solid so far
Posting Tackemon's photos here before they are lost to time...
ZX81/TS1000 RAM module wedge to fix "wobble"

1 The 3D printed piece, width of the RAM module
1 The 3D printed piece, width of the RAM module
2 Tried to show how the piece fits into the little groove in the connector
2 Tried to show how the piece fits into the little groove in the connector
3 Side view of how the piece fits. Made it a bit angled at the edge to help it go in
3 Side view of how the piece fits. Made it a bit angled at the edge to help it go in
4 Snug fit, but doesn't feel forced. So far, no issues
4 Snug fit, but doesn't feel forced. So far, no issues
avrovulcan
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Re: My solution to RAM module wobble

Post by avrovulcan »

I think my solution back in the day was to use a bit of Blu-Tac
David G
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Re: My solution to RAM module wobble

Post by David G »

hmm ... not being familiar with Blu Tac, i looked it up

it seems to be a type of poster putty
Blu Tack was often used with the Sinclair ZX81 microcomputer to help mitigate crashes caused by wobbly external RAM packs.[9] This was such a widespread problem that Sinclair Research's technical support department officially recommended the use of Blu Tack to resolve this issue.

wikipedia
So just a pinch between case and RAM pack?
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1024MAK
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Re: My solution to RAM module wobble

Post by 1024MAK »

Don’t know about now, but back when I was in school (early 1980s), every child knew about Blu-Tac. But this may just have been a U.K. thing.

And yes, it’s still available. The was also white coloured version, but I don’t know if this is still a thing.

Mark
ZX81 Variations
ZX81 Chip Pin-outs
ZX81 Video Transistor Buffer Amp

:!: Standby alert :!:
There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb :!:
Looking forward to summer later in the year.
David G
Posts: 387
Joined: Thu Jul 17, 2014 7:58 am
Location: 21 North, 156 West

Re: My solution to RAM module wobble

Post by David G »

Hey there is a Computerphile video about RAM pack wobble: Wobbly RAM & ZX81 Drawbacks
The thing is what the most important thing about this machine is the thoughts of what you could do with it

not necessarily for a lot of us what we actually did with it
Once again, Computerphile extracts the essence of a machine!
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