[sdiy] how to fix JX-8P keys?

[Robert Shanks]

The JX-8Ps have metal contacts, brass looking fingers with a small  
piece of gold-plated wire welded to it that hit tiny wire bus bars.   
When I was a synth tech back in the 80's and gigging every week, I  
would have to pop the bottom off the beast, take the keyboard out and  
clean & play with the contacts just to get it working reasonably  
well.  (the cobbler's children have no shoes,   (rollie eyes))   
Normal people would have gotten another synth...  but it sounded SO  
good!  Better than my MKS-70 in a way, more punchy.  Anyway, I think  
the gold gets worn on the bus bars and crossbar contacts.

More war stories...  I had an Ensoniq Marage rack that if we played  
outdoor gigs, I guess the heat in the South, would make the big chips  
work their way out of the sockets.  I got so I could play with my  
right hand, pick up an AEG electric screwdriver with my left hand,  
unscrew the Mirage from the rack (2 screws), slide the cover back (0  
screws) and press down the offending chips and keep playing.  All  
this was within one song.  I finally put in better sockets and wire- 
tied those muthas in so they wouldn't go anywhere.  Har, har, the  
good ol days.

back to lurking,
Robert Shanks
Synthlab

On Nov 21, 2007, at 9:39 PM, Bob Weigel wrote:

> These are the rubber cup switch arrangements.  Sometimes they get  
> actual dust/dirt under them.  I just cleaned up an old AX73 of the  
> same technology last night.  WOrked great after getting all the  
> crumbs out save one note that I had to pull the key off from and  
> 'massage' it around with a blunt end probe.  (You can actually kind  
> of fine sand the surface some without even pulling the contact  
> strips out)
>
> Other times (eg. my memorymoog) I've seen contacts be very  
> persistently foul. I'd like to develop something that will really  
> allow people to repair those contacts.  Nickel print won't stick to  
> silicon at all.  Most other things won't either of course.   In the  
> meantime
>
> 1) Sometimes acetone will eat a little of the surface rubber and  
> leave the conductive impregnated material.   Treat it, scale the  
> surface with an exacto etc. and sometimes it's good. Measure with  
> probes.  You should have a conductivity of 500 ohms or less when  
> you press them side by side on the surface of that stuff.  If it's  
> 1000 ohms they are going to be totally flaky usually.  700 might  
> work ok in most apps I've seen.
>
> 2) Light abrasive can sometimes bring them back
>
> 3) Sometimes the contact just seem to have no conductive material  
> left in it! :-)  I have ones from a Mono/poly I did in my studio  
> that simply can't be gotten back..like one or two per strip!  Bad  
> lot of them?  I think so.
>
> That's my research on the matter.  I've even though of...drilling a  
> very small hole..#70 maybe...in the center of a contact.  Then put  
> nickel print on there :-).  I'll bet it would work.  -Bob
>
> Dino Leone wrote:
>
>> Hi all,
>>
>> I have a Roland JX-8P with a couple of flaky keys - sometimes  
>> they  work, sometimes they don't. If you hit them hard they always  
>> work.
>> Before taking the thing apart, I wanted to ask if anybody has   
>> suggestions on how to clean the keyboard contacts?
>> Many thanks in advance,
>> Dino
>>
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