Fatar Contact Boards - changing the polarity DR to DF

[Roloway]

Hello everyone!

2 weeks ago I got a Korg SP100 stage piano in pretty bad shape.

I was able to solve most problems but not the faulty right contact board - the PCB that registers the key strokes and velocity. When I removed it I noticed corroded PCB traces and bad rubber contacts. After some time playing around with it and due to my lack of knowledge and stamina I gave in and went to the local musical instruments repair shop. The people there were helpful and had a used one in stock and sold it to me pretty cheap. When I got home it didn't work at all. None of the keys worked. When I got back to the shop, they noticed that the original board had a different diode polarity and they didn't know if they could get one like this or how much it would cost.

So I started a search on the internet and found out that Korg used a fatar keybed such as the ones in the Doepfer or Kurzweil products.

And also that there are 2 versions of these diode matrix contact boards. They differ in the diode polarity and are called DR and DF versions. This I found out on the MIDIbox forum and that's why I hope there is someone who can shed more light onto this topic.

So I've got a working right side Fatar DR contact board and a broken right side DF contact board. My keyboard only accepts DF boards.

In the following thread I found the DR and DF schematics for a different keybed (mine is 88key, the one here has less keys).

Here the back sides of the boards in comparison:

Is there a way to turn a Fatar DR contact board into a DF board?

Thanks for your help

(My apologies if this is in the wrong sub-forum. Then feel free to relocate this thread).

Edited March 12, 2011 by Roloway