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 Forum index » DIY Hardware and Software » Musical Interfaces
Help! Keyboard springs required!
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bunker



Joined: Mar 19, 2009
Posts: 58
Location: Manchester, UK

PostPosted: Wed Mar 25, 2009 2:12 pm    Post subject: Help! Keyboard springs required! Reply with quote  Mark this post and the followings unread

Hi. Newbie here and I'm not sure if this is the correct section of the forum but here goes....

I am in desperate need of some replacement springs for a keyboard mechanism. The Keyboard is of the 70's Italian flavour whereby one end of the spring is soldered onto the circuit board and the spring itself makes/breaks with a bussbar. The springs are about 1mm in diameter and are roughly 45mm long and look like phosphor/bronze. I can take some pics if anyone needs to see exactly what they look like but I'm sure anyone who has seen the insides of a "cheap" old synth/organ you'll know what I'm talking about....

I would imagine these aren't readily available as 'keyboard springs' but I'm sure something similar would be available from a hardware/hobby supplier somewhere, I just don't know where. Strictly speaking I only need the one for a repair to my beloved Godwin String Concert (THE greatest String Machine imho!!!) I don't mind buying a bulk amount to keep for spares and I'll happily buy from anywhere and have them sent to the UK.

I would rather buy some springs than rip an old instrument apart to cannibalize but if push comes to shove that may be the only option. I'm guessing an old organ would be an ideal donor (and I've got a few of those kicking about!) I am just loathed to rip apart a working keyboard mechanism as I am collecting these for other projects.

If anyone has any ideas they would be greatly appreciated.

Thanks in advance,

Mark.
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bunker



Joined: Mar 19, 2009
Posts: 58
Location: Manchester, UK

PostPosted: Wed Mar 25, 2009 2:26 pm    Post subject: Reply with quote  Mark this post and the followings unread

I'm just wondering if a small piece of bass guitar string of the correct diameter would do the trick?....hmmm..... Might be a bit tricky to solder to the board with that cotton braid inside it....
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bunker



Joined: Mar 19, 2009
Posts: 58
Location: Manchester, UK

PostPosted: Wed Mar 25, 2009 4:56 pm    Post subject: Reply with quote  Mark this post and the followings unread

Sorted! A piece of bottom E string from my trusty 'tele is soldered in and just pulling the key down slightly. I could have used a smaller gauge of string as it a LOT stiffer than the original spring. Nevermind, working well now.

Even better, I managed to cure the lack of slow attack/fast decay fault on the same key. Razz Laughing

The envelope for each key is basically a resistor, polarised cap and inverting op amp by the looks of things. Replaced the 2u2 cap and hey presto! Full envelope again! One of the best features of the synth are the envelopes. One for each key and attack/decay times of around 6 sec at their maximum....Nice! Just gotta fix the one E that doesn't sound on one key and subsequently bleeds through when playing the other E keys. Duff divider chip or one of the passives associated? Confused I'll get there in the end!

Mark
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bunker



Joined: Mar 19, 2009
Posts: 58
Location: Manchester, UK

PostPosted: Fri Mar 27, 2009 3:30 pm    Post subject: Reply with quote  Mark this post and the followings unread

All working again!! Very Happy Very Happy

New 4024 divider and 4069 hex inverter and we are winning!

Shame about the rusty front panel though. Maybe a custom case is the order of the day.... Wink Wink
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magman



Joined: Feb 04, 2009
Posts: 363
Location: Liverpool, UK

PostPosted: Sat Mar 28, 2009 12:00 pm    Post subject: Reply with quote  Mark this post and the followings unread

If you find the bits of guitar string don't work out as well as you would like, I think I may have a few spares for the part you are looking for.

They use a similar spring in the mechanism for the E&MM Spectrum synth I'm currently building and I've got a few spares that may be closer to what you are looking for. The ones I have are about 50mm long, 1.34mm in diameter and have a bugle shaped end at one end.

We're also relatively local, so you're welcome to pop round if you want to.

Regards

Magman
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Flat



Joined: Jun 06, 2009
Posts: 2
Location: France

PostPosted: Sun Jun 07, 2009 11:24 pm    Post subject: Source for those springs ? Reply with quote  Mark this post and the followings unread

Hi all
I'm having the same part sourcing problem...
I'm currently trying to revamp an old upright piano wooden keyboard, adding contacts and controller to make it a midi master keyboard.
I found an old Elektor article (N°132, French edition) using those springs as contacts, but no source for these part was provided in the article.
I too thought of guitar strings, but as it is mentionned, they're stiffer, and IMO the contact quality is not as good as springs wrt long term (the helical springs are silver plated, I think). Should I use silver plated guitar strings ?

Does anybody have any address where to source some of those springs ?
And BTW, as I'm french, do you have the exact english denomination for these parts ? I've been looking on the web, but I'm not sure I use the right words for searching...

As pictures are worth a thound words, here are some photographs of these springs :
http://img522.imageshack.us/img522/8443/dscn5400np0.jpg
http://img261.imageshack.us/img261/3797/dscn5402ar4.jpg

(warning : they're big...)
These are not mine, it's from an old Elka Synthex Wink

Thanks for any help

Cheers,
Flat
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magman



Joined: Feb 04, 2009
Posts: 363
Location: Liverpool, UK

PostPosted: Mon Jun 08, 2009 1:27 am    Post subject: Reply with quote  Mark this post and the followings unread

As far as I know, they were always called 'keyboard contact springs'.

They used to be sold by Maplin Electronics, when they produced organs and synthesisers, but not any more unfortunately.

I have found one supplier so far though that definately has the right looking parts:

http://www.synthfool.com/store/contactspringspop.html

Another possible place (and quite a bit cheaper) is Vintage Planet - here (hint, search for spring on this site):

http://www.vintageplanet.nl/content.html#parts

I suspect you should also be able to source them from this company:

http://www.organservice.com/

Though you would probably have to email the last two companies with your photographs to see if they stock this kind of contact.

Good hunting

Magman
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Flat



Joined: Jun 06, 2009
Posts: 2
Location: France

PostPosted: Mon Jun 08, 2009 1:46 am    Post subject: Reply with quote  Mark this post and the followings unread

Hi Magman.

Many many thanks for your help ! Very Happy

First link (synthfool) is perfect, but a bit expensive for my taste Embarassed since I need quite a large number of them...

I'll follow your advice and contact the two other companies to see if they can help.

I'll let you know here how it turns out, if it can help someone else around here.

Thanks again Wink

Cheers
Flat
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