[sdiy] Roland JX8P maintenance

sleepy_dog at gmx.de sleepy_dog at gmx.de
Sat Oct 20 13:14:38 CEST 2018


Ah, thanks! Will have to try that with the chorus. I guess I'll see what 
contact cleaner spray does, and it can't hurt to order a fiber glass pen 
already :D
I wouldn't even mind to play it from a MIDI keboard... but the key 
action on this one feels rather nice, would be a shame to not repair it.
- Steve

Am 18.10.2018 um 16:23 schrieb Florian Anwander:
> Hello Stee
>
> > Most of the membrane buttons barely work.
> These are not membran buttons, but real momentary switches under a 
> membrane. Roland used ALPs KHC-10901, but other brands make identical 
> buttons using other names.
> Buy a bag of them, desolder the old ones, solder in the new ones.
>
> Having an electrical desoldering gun will make your life much easier.
>
>
>
> > Several of the keyboard keys have issues. Mostly not generating a 
> note, or too low "velocity". One key is somehow mechanically bad, 
> resting slightly angled. (I
> >  have not opened the whole thing yet).
> This is an issue of the keyboard switches. The JX-8P uses a quite 
> oldfashioned key switching (the 3P ist more modern). The switches 
> consist of copper blades:
> http://pics.studiorepair.de/Roland/JX-8P/After_Touch/slides/Roland_JX-8P_9.jpg 
>
> If those corrode, then late contact (=bad velocity) or non working 
> contact is the consequence. Cleaning those is not really easy. One can 
> try chemical contact cleaners, but you have to be sure, that you spill 
> out the contact clead well.
>
> I tried the same with my Juno 6  (similar but not identical keyboard), 
> and ended in cleaning the contacts with a fibre glass pencil - this is 
> the job that Dante planned for his 10th ring of hell of his inferno.
>
>
>
> The distortion is assumingly caused by the BBDs in the chorus. Does it 
> disappear, when you switch off the chorus?
>
> Florian
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