Now that the MG-1 is working I’ve noticed that the intonation’s gone a little off on osc1 (the high C is about 1/4 step flat when the low C is in tune). There don’t seem to be any copies of the service manual online, but there are plenty for the Rogue. Is the calibration procedure essentially the same? Do I have to wait until I’ve gotten a new battery for my VOM, or can I just tune the lowest note and then adjust the intonation trim pot until the highest note’s in tune?
Incidentally, is there a documented mod to invert the Envelope when it is modulating the filter (i.e. to make it sweep downward instead of upward)? I haven’t really researched this specific much yet, but when I was doing general research on MG-1 mods I didn’t notice anything like that. The upward sweep is a little too stereotypical even for me.
I am not a tech. I wish I was. : )
But it sounds like your first oscillator just needs to have the “range and scale” process… that which makes sure the key voltages actually generate the pitches you want from the bottom of the keyboard to the top. Basically, it’s a little like stretching a graphic file to fit into a frame. You keep tugging on each end to make sure it fills the gaps!
I remember doing this with my Micromoog at one point, but I don’t remember the exact process… there are trimpots inside (or perhaps accessible through holes in the back) of your MG-1, and basically, you would use the appropriate trimpots to stretch the range of the oscillator so the top and bottom notes are in tune with the notes they should be in tune with at the same time.
Someone must have a service manual on here!
I just bought an MG-1, I might need this info, too! : )
i’ve finally started scanning the service manual/schems last night. should have it online later today for your dudez.
this is my contribution to the world. a free online mg-1 service manual.
maybe i’ll get to the owners manual too…
Thanks so much! Someone local gave me the basic information I was after, but the full manual will be immensely helpful.