Roland Jupiter 6
I own a Jupiter 6 since late 2009 and did before some repairs on this beautiful synthesizer. I provide a pictured documentation of a restoration and Europa-Upgrade I did in April 2009 for a friend. For the future I will document also some modifications I did on Jupiter 6's.
Also the Service Manual (32MB) is available here.
Modification No.1: Change VCO2-to-VC01-modulation to VCO2-to-VCF-modulation
While VCO-to-VCO-modulation cannot be played tonally, the VCO to VCF modulation can be played tonally and is an increadible enhancement for analogue subtractive synthesizers tonal possibilities. Usually it is dead simple to achieve - also at the JP6:
Disconnect R51* (=output of Xmod VCA) from pin 15 IC33 (VCO1) and connect it to pin 6 of IC48* (=cv summing point for VCF).
see the blue marking in the schematic (882kB)
see the blue markings in the pcb (2MB)
This is a modification I did not yet try, but it looks idiot proof to me. If any tries this, please let me know about your results.
*) later models have different partnumbering: R41 to IC49
Modification No.2: Change logarithmic VCO2-to-VC01-modulation to linear FM
I recently acquired an JP6 ( :-))) ) and when I thought about trying the Modification #1 it came to my mind that the CEM3340 offers a dedicated input for linear FM. So: why not try this one of the Crossmodulation. Brief description:Disconnect R51* (=output of Xmod VCA) from pin 15 IC33 (VCO1) and connect it via an additional 100nF capacitor and a 1Megaohm resistor (in series) to pin 13 of IC33.
see the orange marking in the schematic (882kB)
see the orange markings in the pcb (2MB)
This is a modification I did not yet try, but it looks idiot proof to me. If any tries this, please let me know about your res ults.
*) later models have different partnumbering: R41 to IC49