[sdiy] Various repairs coming up...

[ASSI]

Hi list,

I've had some time to look after the old analog gear and place it 
properly into a new keyboard rack. It turns out my Matrix-12 did get 
the aftertouch upgrade after all, and it is even somewhat useable. 
However "channel pressure" has to be taken very literally, it takes a 
lot of force to get full response, which is why I originally  thought 
there was no sensor. There are two trimpots labeled T1 and T2 where the 
sensor is connected (right next to the PC900 that does the MIDI) - is 
it possible to adjust the sensitivity there and if yes, how?

The hum in the PSU can be traced to the primary transformer, it hums 
just the same with and without load. It puts out just under 18V~ 
unloaded, which would be double the voltage in the Xpander (I only have 
the service manual for the Xander), also it is a full bridge rather 
than half bridge rectifier with middle tap. My plan is to replace the 
IEC receptable with one that has an integrated EMI filter and the 
transformer with a toroidal one - the 50VA type from Conrad would be an 
ideal fit while the 80VA type would need a new hole for the mounting 
screw. The Matrix-12 is rated at 60VA, does anyone have the current 
spec for the secondary voltage (the toroids are more efficient, so 
maybe 50VA should be enough)?

BTW, does anyone have the mounting pattern for the individual voice 
outputs? The next time I come near the Matrix-12 with a soldering iron 
I'll put in the connectors on the voice boards. My original idea was to 
put a connector for a multicore into the back, but the original mod 
from Oberheim had the individual ouputs to the left side.

Last but not least the switches on my EX-800 start to misbehave, which 
is especially annoying and severe with the switch that toggles between 
program and parameters. If anyone knows a suitable replacement, please 
let me know, the only thing I found that looks remotely compatible is 
surprisingly Conrad 707678-33...


Achim.
-- 
+<[Q+ Matrix-12 WAVE#46 microQkb/Omega Andromeda XTk/30 sonic heaven]>+

SD adaptation for Waldorf microQ V2.22R2:
http://homepages.compuserve.de/Stromeko#WaldorfSDada