[sdiy] Repairing Key Contacts (OB-8)

[Tony Clark]

> Hi Tony,
> 
> so you found reed switches to be useful indeed? 

   Yes, but it's rather tricky.  The main problem is that the magnetic 
field varies from magnet to magnet, so the more powerful the field, the 
further away from the switch the magnet should be to provide reliable 
on/off operation.  Otherwise what will happen is you press a key and.. it 
never turns off!  Or in the reverse situation, if the field isn't strong 
enough, the key will never turn on!
   With a J-wire keyboard this isn't much of a problem because since the 
reed switch is floating between the buss bar and the J-wire contact, you 
can just bend the switch closer or further away from the magnet 
(positioned on the key).  Might be more difficult with a membrane 
keyboard since the switch would be fixed and you'd have to vary the 
location of the magnet.
   It's not a cheap solution, but it is one that works and is easily 
compatible with existing setups with little modification.

> I wouldn't mind if it gets pricey, something like $200 or more is
> definitely worth investing for a durable solution (well, maybe not quite
> for a Polysix, but at least for an OB8 or Memorymoog).

   A reed setup should definately be under $200 for a 61-key keyboard.  
Probably under $100.  But you'll make up for that in labor!  ;)

   Cheers,

   Tony

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