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Old 12-25-2015, 04:21 PM
caronte23 caronte23 is offline
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Join Date: Dec 2015
Posts: 2
Default Yamaha SK-30 12x7 matrix

Hi everyone, I've been meaning to retrofit a UMR2 into my sk..
After some research I found this thread:

The main problem seems to be the high voltage (15V)
John in this thread suggests to use diodes and resistors as crude voltage regulators, and relays for letting the UMR2 output the 15V for midi in.
I'm waiting for a response from the thread starter (David) to know if he succeeded in this mod..

Meanwhile I was wondering how would I have to set it up in my case...
The Sk-30 has a pretty weird key matrix, probably due to the splitting capabilities..
So the main MK board outputs 12 data lines and 7 select lines instead of the 5 on the sk15...
However after a series of processes, the select lines that hit the key assigner chip become 12 as well. You can see from the diagram the lines are multiplied when combined with signals coming from SP1 SP2 and MB namely split 1 split 2 and manual bass.

My question is, would it be enough to patch into the first 7 select lines, ignoring the subsequent switching or would you patch after the lines are split?
Second question, either way I'd need 2 UMR2s right? How would they be chained? would I be able to have a single midi in and out?

Here are some diagrams, the whole service manual can be found here:
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