Hi everyone,
I was just wondering if anyone could post a quick guide to intoning both the MG-1 and the Rogue. I know it’s been mentioned before but I can’t seem to find the MG-1 info.
Additionally, on one of my MG-1s (which I play live so a backup has been invaluable), I replaced the sliders for the Tones - and now the Moog produces no sound! When plugged in, it makes a padding thumpy sound, but no notes! Disaster, I’m sure you’ll agree…
Any help would be right good, like.
Thanks!
Davo
the MG-1 service manual is downloadable from here:
http://moogmusic.com/forum/viewtopic.php?t=3388
if that helps at all
By intoning do you mean recalibrating the oscillators? Just download the service manuals and follow procedures. Be sure the keyboard scale is OK with a DMM before you start tuning. It seems confusing at first but once you find the correct way it´s all very straightforward: for example, to compensate for the narrow freq range of the Rogue I just tweak R51 to make osc2 an octave lower than osc1, with the interval knob in unison position…
(To avoid damaging R51 through overuse I decided to change R85 value to 33K but this is another subject).
It helps if you have a digital synth playing a pure waveform (no effects or detuning oscs) to tune by ear, or you can download a guitar tuner program such as http://www.programurl.com/ezytuner-guitar-tuner.htm.
Recalibrate the VCA to end the thumping sound and if you used too much solder flux while replacing the sliders clean the joints with alcohol as the flux is conductive and is probably causing a short.
Edit: no offense but… usual disclaimer here… do it at your own risk blah blah blah…
Flux is conductive???
Too much flux might cause probs on very high impedance circuits, but generally it’s no problem. Sometimes wire or solder bits can get lodged in it and cause a short, but conductive? Am I missing something?
I think it depends on type of flux and the circuit.
Recently at my work, I was prototyping a circuit that ran on very high voltage (>1500V), very low current and had very small surface mount components. I had to scrub the hell out of that thing to make sure there was no flux on it, because it could (and did) create some bridges. I asked around at work a bit and I’m pretty sure it was the flux causing this. However, it is entirely possible that it was caused by tiny particles getting stuck to the flux, not the flux itself. At that high a voltage and that small components, it doesn’t take much.
But I don’t think flux is going to cause bridging in a synth.
I meant solder paste, not solder flux. Here we call “fluxite” to both the paste and the rosen core. If it´s the same case I stand corrected.
Always had this idea of soldering paste to be mildly conductive and witnessed some arcing between good joints that weren´t cleaned, but hélas it was a valve amp. Still, cleaning the board after soldering won´t hurt, right?
And, if you only picked at the flux bit that means I was right for the most part of my reply 
especially the disclaimer part 
so let´s hope it helped the original poster and anyone dealing with the same problem.
Flux is not conductive but as it ages it does provide an impedance path for leakage, especially in high impedance circuits. I have cured circuit misbehavior by scraping off dried excess flux.
There is this fascinating website about synthesizer restoration with lots of “before/after” pictures, from where I learned a lot, but this “after” picture in particular puzzled me. My soldering joints don´t look like this, even before the cleaning. It looks like just core flux was used and no paste at all.
After reading about stray bits of wire and solder particles I browsed through a DIY audio forum and there it seems the general consensus is: either remove the flux completely or left it as it is. The danger resides in poor, half-done cleaning jobs 
I use water soluable flux and I’m pretty sure that not only will the water-soluable flux corrode the solder joints over time (unless washed) but also have been known to carry small amounts of current between joints. This is just what i’ve been told by the boss. I’m not sure about no-clean though, when left on that might actually be considered more of an insulator.
This is mostly speculation, i’m sure there are some good IEEE documents out there about this though.
I tend to clean up flux, but for the reasons such as MC expressed.
Around high impedance circuits like keyboard memory, sample and holds, glide circuits and the like, the added flux can cause leakage.
In VCO’s, high frequency dissipation which can cause tracking errors.
Flux can also absorb some moisture, which obviously isn’t a good thing for a sensitive circuit.
I also like to clean it off because… and especially with recent ROHS solder… small balls of solder can “spit” from the connection being made.
On widely spaced connections, it doesn’t make much difference.
But I like to be sure there’s no shorts on things before I power them up and on finely spaced pads or traces, it can require cleanup to be sure.
(holding a PCB up to a bright light can also help identify shorts sometimes.)
On some synths, such as the Multimoog, a high frequency oscillator is used both for the keyboard triggering and aftertouch. These signals can bleed sometimes given flux on the board.
Regarding that photo, that’s the way most Oberheim gear was for that period.
I often clean it off, but simply to be neat or to locate any possible shorts.
Usually Oberheim cleaned their flux away from their FETs and other megaohm sensitive circuits, but they obviously didn’t do it everywhere.
The units of this era were often hand soldered in the US.
Not cheap, even for the 70’s.
Hi all,
thanks for the replies - anyone have any thoughts on the second part of my question?:
"Additionally, on one of my MG-1s (which I play live so a backup has been invaluable), I replaced the sliders for the Tones - and now the Moog produces no sound! When plugged in, it makes a padding thumpy sound, but no notes! Disaster, I’m sure you’ll agree… "
Thanks!
open her back up, re-check these:
Fwiw, whether the sliders were audio, linear, 10K, 100K or 1meg, shouldn’t make a difference. If they’re all up and there’s no sound, something’s wrong.
(the sliders should be 10K linears, fwiw)
Other than that, as the man sez… Recheck!! 
Good luck!
Oh and this page might be interesting too:
http://www.geocities.com/gallomagnetix/mg1x.html
wow! nice link!
Whoever made that page did a very good job with the diagrams and such.