Ensoniq KS32 Keys dead and some extra loud


#1

Ok I might be a board level tech from the old days but sometimes I kick myself for going all in with something I have no idea about…Hopefully I;ve not done too much damage yet!!

Wife complained about a couple of keys being extra loud so I decided to have a look. If I understand the workings correctly then the carbon contacts under the rubber boot are slightly different in height so that one makes contact before the other thus the KS32 can determine how fast you have hit it and thus determine how hard and thus loud you make the sound. Is this correct? it would then mean that a bit of dirt in the dips above the rubber boot would be enough to cause the problem. This unit was pretty dirty so I cleaned all that externally. I then possibly made a mistake… I lifted the rubber boot in this area and very lightly cleaned with a cotton bud some of the carbon contacts and the board contacts with alcohol, I now have dead keys. Is it really possible I have removed too much of the carbon off the contact? Is this contact that sensitive. Any thoughts and knowledge would be appreciated or I’ll be in the doghouse if i can’t fix this when i get home tonight. Also curious about the two contact strips that one runs the length of the black and one the length of the white keys. Looks like a pressure sensitive strip and plugged into the board below the pitch wheel, how are these strips used and is it only on particular sounds. Thanks for any info.


#2

You are correct in your assessment of how the contact strips work - the difference in timing from the two nubs making contact tells the processor at what velocity the note was played. It’s a common issue for keys to play at full velocity or not play at all when the contact strip is failing. You can try washing the strip in warm water with dish soap, but if that doesn’t help, it likely needs to be replaced, as the carbon can eventually start losing its conductivity. The replacement 12-note strip is here:

The other parts you refer to are the aftertouch strips. Here is the white-keys strip:

These sense how hard a key is being pressed after the note is triggered, so that you can use aftertouch to bring in vibrato on a held note, for instance, or to open up the filter as you press harder. These are parameters that are programmed into each sound individually. So you will likely find that aftertouch has no effect on a piano sound, but it may add vibrato to a trumpet sound. On the KS-32, I think you select a MOD=PRESS to implement this.


#3

That’s brilliant Sam I really appreciate your reply. What about the carbon contact on the PCB, does that also do the same thing and loose conductivity, if so I would need to replace the longer of the PCB’s as well or do a cheat with some conductive paint/material if I wanted to be creative.


#4

That area could be faulty also, but in our experience, the culprit is nearly always the rubber strip. Unless you see visible damage to the PCB, I would replace the contact strip first, then if you still have trouble go after the board.