Hello,
Is the rotary switch on this layout wired correctly?http://www.generalguitargadgets.com/v2/diagrams/mxr_p100_lo.gif
I built this pedal about a month ago and couldn't get it to work with the switch wired this way.I searched the forum archives and read a post that said it was wired backwards, without any other details.So, I just switched the two center pole connections, and it worked, with one hitch, it only works on three positions of the switch :?
The sound of the phaser is nice but the switch doesn't seem to change the sound of the effect that much at all either.
Thanks for any comments or help with this issue.
The switch provides the four combinations of two width settings, and two resonance settings. The LFO is a little complicated so installing a variable width setting to replace the switch with a pot might be tricky. On the other hand, the resonance settings are basically two different resistances (15k vs open circuit). Absolutely no reason why the 15k resistor couldn't be replace with a 10k and a 100k-250k pot in series for variable resonance. Then it's simply a matter of a two-position toggle for the width aspect.
Here's what I wrote down a year or two ago. References refer to the schematic not the layout you posted the link to.
"This is what I can make out from the pictures on the face of a real MXR unit:
Position Characteristics.................Left Sw Right Sw
1........Narrow sweep+ Non-resonant.Closed Open
2........Narrow Sweep+ resonant.....Closed Closed
3........Wide sweep + Non-resonant. Open Open
4........Wide Sweep+ resonant...... Open Closed
Positions refer to the original circuit positions, with position 1 being where the pointer points to the left - switch rotated clock-wise. (The rotary switch appears to be mounted upside down on the MXR unit)
Left sw/Right sw Refer to the contacts on JD's schematic. To be honest, I can't really make out what was intended from the schematic (No offense JD!!).
I can see that the trim pot may need to be adjusted in narrow mode to get it to work, and that this setting may conflict with the 'optimum' setting in wide sweep mode. You might have to make some value adjustments to optimize both."