Martin's Acorn Atom (keyboard)

discussion of games, software, hardware & emulators relating to the Acorn Atom
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martinw
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Martin's Acorn Atom (keyboard)

Postby martinw » Thu Sep 13, 2012 10:07 am

So I managed to buy an Acorn Atom on fleabay for less than £100, no mean feat these days. I bought it from the son of David Aubrey-Jones who apparently used to be an 8 bit programmer back in the day, but mainly on Spectrums according to Google, anyway, I digress.

As you may guess it's not in mint condition, but not too bad really, no burn/scorch marks to talk of and the PCB is in reasonable nick. I will probably post some more threads on the Atom but this one as the title suggest is on the keyboard. There are though two key inserts (that sit beneath the actual keys themselves) that have broken.

The key insert and associated springs/contacts is shown below.

Atom Key.JPG
(19.03 KiB) Downloaded 1009 times


The image (without the springs, they're mine you can probably tell) is courtesy of the gentleman I bought some new (to me) key inserts from, I hope he doesn't mind but I have spent about £15 (I bought some spares too) with him so he should be OK.

Some kindly person has tried glueing the keys back onto the broken stumps, fair enough I suppose but after a bit of effort and my pillar drill with a 0.8mm bit in it I now have keys without broken inserts glued into them =D>

So the next thing was getting the broken inserts out of the plastic insert cage (I forgot to mention it's an issue 4 I think). I saw a video online of a method of getting them out (again I think by gentleman selling the inserts) but after a bit of prying with a knife (as shown in the video) I started to worry I would break the thing that I wanted to keep, i.e. the platic cage.

You've probably heard of the saying when all you've got is a hammer everything starts to look like a nail, well in close proximity to me there was a pair of snips. So gingerly to start off with I placed the snips in the middle of the insert (whilst holding it as high up out of the cage as possible) an squeezed. Hey presto the insert split in two and virtually fell out of the plastic cage =D>

I did this on the second problem insert too and all worked out fine, so far ......

My question is this, being an engineer I like to know how things work. I can't really see inside the frame much but can see the springs (as sort of shown in my drawing). Is there any possibility I have misaligned the springs whilst doing what I did, as if I push my new inserts in there and work out there's a problem the way I get them out is ever so slightly problematic for the insert, snip :!:

Do the long ends of the springs have to actually make contact with each other somehow when the key is pushed down or is there something else in there that makes the circuit :?:

Thank you in advance for any help/insight you may have on this.

Martin

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Re: Martin's Acorn Atom (keyboard)

Postby 1024MAK » Thu Sep 13, 2012 11:39 pm

Well, I'm no expert on Atom's, but I have seen a fair few keyboard switches. In most, a contact makes the circuit, not the coiled spring(s).

Mark K.
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Re: Martin's Acorn Atom (keyboard)

Postby martinw » Fri Sep 14, 2012 8:26 am

That would definitely make more sense. I might send an e-mail to the guy who sold me the inserts as he must have had one in quite a few bits looking at his video.

Like you say (and if I were a betting man I'd say) there must be something (a contact) in the plastic frame at the bottom that makes the circuit when the two legs on either side get pressed down.

Possible Atom Key.JPG
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The lip on either side of the middle post stops the key popping out of the frame once it's in there.

I may even desolder the frame itself to see what's going on as some of the keys have a very peculiar action at the moment where multiple characters are displayed for one key press.

Probably because they haven't been pressed much for a long time ......

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Re: Martin's Acorn Atom (keyboard)

Postby martinw » Sun Sep 16, 2012 8:35 am

OK It's now in bits :shock:

Here are those bits ......

Atom Keyboard Frame.jpg
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So from what I can see now the springs do do all the work.

See below ......

Atom Spring Keyboard.jpg
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The little pieces of plastic within the enclosure do some of the work too, best seen on the one without the key insert in there.

A couple, one on each side hold the springs apart when disengaged, which is not easy to see from the angle I've taken the photo, as it looks like they're touching but they're not (or at least they're not when the key insert is in there).

Another two, one on each side are rails to allow the insert to move up and down in the vertical, and the two in the middle stop the insert from popping out.

Simplez ....... :roll:

So now it's refurb time for the keyboard frame ........ :)

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Re: Martin's Acorn Atom (keyboard)

Postby 1024MAK » Sun Sep 16, 2012 8:55 am

I don't suppose you could take and post some better pictures :?:
Only it is hard (for me at least) to see what you are talking about in the current picture...

Mark

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Re: Martin's Acorn Atom (keyboard)

Postby martinw » Sun Sep 16, 2012 4:43 pm

Atom Keyboard Insert.jpg
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To say these things are fiddly is a bleeding understatement, BTW I found super macro on my camera, hence the more zoomed in shots.

Atom Springs & Insert Outside Frame.jpg
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In order to get the springs back in the frame takes the patience of a saint [-o<

The bottom tail has to go through the little "nick" in the bottom, the circular part of the spring then has to be pushed on the little lobe at the bottom.

Atom Springs In Frame Showing Spring End Holder.jpg
(247.15 KiB) Downloaded 823 times


Then the spring has to be twisted slightly to get the top tail of the spring into the rectangular hole where the insert goes in. It then has to be pushed down into the hole slightly.

So when both springs are in, after about an hour =D> you can see they're held apart by the plastic bits in the frame.

Atom Springs In Place No Insert.jpg
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Then when the insert is pressed down the contour of the plastic bits (in the frame) holding the spring tails (at the top of the springs) apart then allow then to come together and meet.

Atom Springs Touching Insert Down.jpg
(91.71 KiB) Downloaded 823 times


CONTACT =D>

Hopefully this is a bit clearer now :?:

Martin

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Re: Martin's Acorn Atom (keyboard)

Postby 1024MAK » Sun Sep 16, 2012 5:04 pm

Hey Martin

Thanks for the brilliant pictures =D>

Your post makes it a lot clearer how they work.

Thank you :D

Mark
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Re: Martin's Acorn Atom (keyboard)

Postby martinw » Sun Sep 16, 2012 6:09 pm

Not a problem Mark, I didn't even realise I had a super macro on my camera, so I learned that by trying to take some better pictures, so thank you to you too :D

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Re: Martin's Acorn Atom (keyboard)

Postby martinw » Sat Sep 29, 2012 2:24 pm

In another thread I posted the comment something along the lines of "now I just have to solder the keyboard back on the PCB". A short sentence but little did I know, a lot of sweat and tears has gone into getting it back on the board.

So to set the scene, I now have all the key inserts and springs back in the keys that were broken or not working properly.

One tip if ever anybody takes their Rev.4 keyboard off their atom PCB (BTW DON'T :!: unless you really have to and have a lot of patience) is in order to get the springs back in the use of a scalpel worked pretty good for me, because once the bottom tail is pushed through the small "nick" on the bottom it is then necessary to spin the top tail by about 90 degrees (BTW hold on to the tail at the bottom while you're doing this) to get it back in the place it needs to be at the top. Just twisting the top tail causes the spring to fold over on itself. The scalpel digs in slightly to the top of the spring, from which point you can then twist the whole spring to allow the tail to move around to where it needs to be.

Another tip is if you have a broken insert that you can use to press the two springs down without actually sealing everything in the hole, do that before you put your good insert in because sometimes the top spring tails are not long enough (after they've been removed from another keyboard) and don't touch properly when compressed.

Finding this out before you've assembled the whole key insert assembly is a really good thing :wink:

So once I was happy with all the keys, checked with a multimeter I then did this.

How NOT to do it.jpg
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Bad move, do not do this if you're reading this. The gauge of the wire was too much and the spring tails which are very fragile and wobbly and don't always point in the direction you want them to weren't able to take it as I tried to get the wires in the hole.

BTW if you're thinking why didn't you just push the keyboard down onto the PCB and solder it ........ easier said than done for the reason above, they go off in all directions and are not very stiff, so they're not like IC pins.

Anyway as I tried to push the wires and assembly above into the PCB, it turned into a veritable mess, broken springs trapped wires, lots of swearing :oops:

So this is how I managed to do it in the end, see pictures below, using Ethernet cable wires stripped out of the cable.

How TO do it.jpg
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How TO do it 2.jpg
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How TO do it 3.jpg
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Once I was happy all the wires were through the holes as well as they could be I then trimmed off the excess wire and wiggled the wires though the holes until the keyboard was flush with the PCB, using the screws that hold the keyboard on the PCB was useful at this point but I was careful not to trap any wires.

How TO do it 4.jpg
(176.81 KiB) Downloaded 729 times


Then I desoldered the Ethernet wires and resoldered the springs in their holes :D

Not an easy task by any stretch of the imagination and there may be other ways to do it, but after about 3 hours ........ I now have a fully functioning Atom with no broken keys!

Success!.jpg
(120.34 KiB) Downloaded 729 times


Phhheeewwww!

I just thought I'd share for anybody else finding themsleves in a similar position :wink:

Martin

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Re: Martin's Acorn Atom (keyboard)

Postby daveejhitchins » Sat Sep 29, 2012 5:11 pm

=D> =D> =D> =D> =D> Well done Martin W. =D> =D> =D> =D> =D>

Another Retro Machine saved from the Bin :D

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For a price list, contact me at: Retro Hardware AT dave ej hitchins DOT plus DOT com

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Re: Martin's Acorn Atom (keyboard)

Postby 1024MAK » Sat Sep 29, 2012 7:38 pm

Phew, that looked like it was a painful job :roll:
I bet you're glad its all over and done with.
Nice work there, and well done for persevering :D =D> =D>

Mark
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Re: Martin's Acorn Atom (keyboard)

Postby CanonMan » Sat Sep 29, 2012 8:43 pm

Great work there. You've got more patience than I have :lol:

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Re: Martin's Acorn Atom (keyboard)

Postby martinw » Sun Sep 30, 2012 8:51 am

Thank you ...... once I'd taken the keyboard frame off the PCB, a few times through the last couple of weeks I've thought "I'm never going to get it back on and working" :cry:

But I felt I owed it to the little Atom to work it out and get it back up and running, which eventually I've done, and I'm pleased as punch :D

These 8 bit micros take over your life sometimes; which I suppose is all part of the fun :lol:

Martin

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Re: Martin's Acorn Atom (keyboard)

Postby leenew » Sun Sep 30, 2012 9:47 am

Absolutely marvellous work =D>
Well done.

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Re: Martin's Acorn Atom (keyboard)

Postby MartinB » Sun Sep 30, 2012 12:33 pm

Obsessive Compulsive Repair Disorder - Excellent =D>

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Re: Martin's Acorn Atom (keyboard)

Postby paulv » Sun Sep 30, 2012 1:02 pm

Wow. Nice work. =D> Your attention to detail and patience is self evident in those photo's. A master class in Atom keyboard overhaul!

Paul

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Re: Martin's Acorn Atom (keyboard)

Postby 1024MAK » Sun Sep 30, 2012 2:19 pm

MartinB wrote:Obsessive Compulsive Repair Disorder - Excellent =D>

:lol: :lol: :lol: :lol: :lol:
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Re: Martin's Acorn Atom (keyboard)

Postby peterj » Sun Sep 30, 2012 4:05 pm

Yes I love to see when somebody elses plan all comes together nicely.

Peter

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Re: Martin's Acorn Atom (keyboard)

Postby martinw » Sun Sep 30, 2012 5:16 pm

MartinB wrote:Obsessive Compulsive Repair Disorder - Excellent =D>


Guilty :D

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Re: Martin's Acorn Atom (keyboard)

Postby oss003 » Sun Sep 30, 2012 5:22 pm

Hi Martin,

I did a lot of things with my Atom but never a keyboard transplant!! :D
Nice work doctor Martin!! =D>

Greetings
Kees

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Re: Martin's Acorn Atom (keyboard)

Postby decle » Thu Apr 27, 2017 8:33 pm

Hi all,

This seems to be the most comprehensive thread on repairing issue 4 keyboards. My issue 4 project started with 6 dead keys and one sticky one. A bit of key pounding recovered one dead and the sticky key. Reflowing and connecting loose spring whiskers on the underside of the keyboard brought another 3 back to life. So I'm left dead R and Y keys. They have whiskers poking through the PCB that are connected to the pads. They seem to have similar resistance on both sides. I've tried contact cleaner and an air duster. I'm guessing something is bad inside. Other than reflowing the whisker connections and fiddling with them in the hope it realigns something inside I'm a bit out of ideas.

So does this thread still represent the state of the art in issue 4 keyboard repair? If I mangle the inserts as described here is there a place to get replacements or indeed replacement springs?

All thoughts and pointers are most welcome.


Thanks

decle

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Re: Martin's Acorn Atom (keyboard)

Postby numbersix » Sun May 28, 2017 2:21 pm

I'm just starting to refurb my Atom and I've got the list of faults down to just non-working Y, F and C keys. I've tried contact cleaner and working them a lot and also reflowing the solder and that's only helped resurrect the H key so far. Is there any way of getting the inserts out from the top, or am I going to have to remove the entire keyboard frame as Martin has done? I think I might be at the limits of my dexterity and patience there, I'd hate to make it worse rather than better given the rest of the machine is in pretty decent condition!

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Re: Martin's Acorn Atom (keyboard)

Postby martinw » Thu Aug 03, 2017 7:50 pm

Sorry for not replying to these comments earlier.

The way I "fixed" my keyboard cost a lot of money, as I had to buy a lot of springs and inserts.

My philosophy was, I can't break the frame so if I damage an insert it's not a problem as I have spares.

Getting the inserts out is not easy and I just broke them (only a few) to get them out :oops:

Getting everything back together was equally difficult.

I have spares but am a little reticent to let them go as I may need them in the future, especially the inserts.

There was talk of 3D printing them but they are small with a lot of detail on them.

Martin

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Re: Martin's Acorn Atom (keyboard)

Postby martinw » Thu Aug 03, 2017 8:29 pm

My Atom spares and their special box!

IMG_5195.JPG

IMG_5196.JPG

IMG_5197.JPG

IMG_5198.JPG


Martin

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Re: Martin's Acorn Atom (keyboard)

Postby bprosman » Thu Sep 14, 2017 6:25 pm

Smelly parts :D

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Re: Martin's Acorn Atom (keyboard)

Postby martinw » Fri Sep 15, 2017 11:31 am

:D


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