SP-808 - Values of knobs are jumping

[putte]

I hope my english is sufficent enough to explain my issue:

From time to time the values of effects are jumping around wildly when using the knobs. I only make use of the cut-off and resonance filters when performing live.
I already made use of a spray on the knobs, but somehow this didn't fix it.

Any hints?

[l i f]

My 808 has slowly been developing the same problem since about a year ago (bought it new in '99).. first the resonance/ctl3 and more recently the cutoff/ctrl2.

I found a temporary fix to be to remove the knob and tighten the screws around the base of the potentiometer. This got me a few more months out of them, but the problem has slowly been getting worse with the values jumping around erratically, just as you describe.

My solution now is to go into the effects-edit menu, turn off the knob-assign and edit effects using the vari-pitch/jog wheel. This works in a studio-session, but maybe not so good for live-work. You MAYBE can reassign the filter-cutoff to one of the knobs that still works - certainly you can do this with general effects in row/a but I'm not sure if it will work on row/b, filter/isolator - they may be permanently-assigned... try it maybe.

I contacted Roland mbe 6 months ago regarding this problem after finding a copy of the sp808 service notes buried in the old sp808 Users Network. OTBT has uploaded it here: viewtopic.php?f=10&t=23972&hilit=808+service+notes

Roland tells me parts are available easily-available thru any authorised dealer and I remember the potentiometers being quite cheap. What gets me is how insanely complicated (and likely, costly) installing them will likely be given how many layers of circuitboard are stacked inside.. daunting stuff.