How do you calibrate a Mutron II Phasor?

[Dr Ron]

Does anyone know how to calibrate a Mutron phasor?

I've repaired one with the help of some people in this forum, but am not sure how to calibrate it for optimal tone.

I have the repair manual that tells how to do it with a sweep generator, but I have a function generator. Also, words really don't tell you what the image on the scope should look like.

I set the FG to a few kHz, turn the Phasor knobs full up, and began with the 2 calibration pots at center. I calibrate it to make the waveforms look good based on what I think the manual says ... just under the flat part for the LDR driver and minimize the bump between sweeps for max range.

I think it sounds cool, but some people mention that these pedals have a special unique tone that professional calibration brings out.
Others state that you can't rely on the scope to calibrate for best tone.

The auto-wah has only one calibration pot, while the phasor has two and they seem to interact with each other, which makes it confusing.

Any advice?
How do you do it?
Am I on the right track?

Thanks

Ron

[StephenGiles]

http://www.geocities.com/dbalde.geo/musitronics.html

Presumably you have the circuit diagram, if not you will find a poor scan here which perhaps with a magnifying glass will give you a clue as to what the presets do. However, in 35 years I have always set up a phaser by ear

It would have been far more sensible to scan using a much higher resolution, large files are of no consequence these days!

[Dr Ron]

However, in 35 years I have always set up a phaser by ear

The problem is that I'm not really sure how it's supposed to sound.
Each time I reset the calibrations, the sound changes a bit, but it's still very cool.
It goes from a mild / transparent effect on low, to bubbly swirls on 10.

There's a web site with sound samples, but they sound completely different than this unit and my amp/guitar.

I suppose my trepidation is solely because this is the first time I've used one of these.

[StephenGiles]

Ah, I understand your problem. Looking at the circuit, my tired eyes just cannot read the notes handwritten by the presets, but it looks as if they might adjust the shape of the control voltage. Can anyone else help out here please? I'll see if I can locate a clearer diagram.

[StephenGiles]

Sorry, I cannot find any clearer circuit diagram for this - ah maybe a good old analog magnifying glass would be better!

[Derringer]

There's these in the gallery ...

http://www.aronnelson.com/gallery/main.php/v/RLBJR65/Mu-Tron+Phasor+II+pg1.GIF.html

http://www.aronnelson.com/gallery/main.php/v/RLBJR65/Mu-Tron+Phasor+II+pg2.GIF.html

[StephenGiles]

Well, there you go! Thanks, so presumably the 1k trim simply trims the level of the current applied to the LED?

[Derringer]

appears to be that way