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

[Bob Weigel]

Hmm...there must be a couple versions of that movement in JX8P. The JX10 
definitely had the rubber contacts as do the JUNO-106.  I've never 
worked in the 8P for whatever reason.  That one seems to have steered 
clear of me so far :-).  I think I've done every other board except the 
JP6 and 8 and module also from the era save the mks50.  But I seem to 
recall there was even a weighted and unweighted version in selling 
people keys I discovered I believe. 

Robert Shanks wrote:

> 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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>>>
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