Mutron Phasor - Tick heard in the sweep

Started by cjlectronics, March 22, 2011, 11:04:46 PM

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cjlectronics

I am working on a first version Mutron Phasor that has a tick in the output signal and the tick changes speed with the rate knob.  I am hoping someone may have seen this problem or can play their Mutron Phasor and tell me if a tick can be heard in their sweep. Here are a few facts:

1. I've searched this forum and found lots of info including a schematic.  However, no issue with a tick in the sweep.
http://www.experimentalistsanonymous.com/diy/Schematics/Phasers/Mu-tron%20Phaser%202.jpg

2. I checked the voltages with a scope... they are clean and no ripple or I should say the ripple on the negative power rails is below 10mV p-p. The positive rail has no ripple.
3. The few electroytics in the circuit I've swapped out.  I think there were 3.
4.  I haven't reflowed ALL of the solder joints but I may do this as a last resort.  The solder joints look OK.
5. The tick can be heard in both effect ON and bypass mode.

Hopefully someone can help me see something I may be overlooking as a possible problem.

Thanks,

CJ

cjlectronics

I realized I supplied the wrong link to the schematic.  The correct link to the first version Mutron Phaor is http://www.beavisaudio.com/img09/MutronPhasorFactorySchematic.jpg


CJ

MoltenVoltage

Have you looked at the LFO output?

It sounds to me like the waveform needs to be adjusted.

I've only worked on the Phasor II, but, if I remember right, there are trimpots that adjust the LFO output.

Just don't turn them to the extremes.
MoltenVoltage.com for PedalSync audio control chips - make programmable and MIDI-controlled analog pedals!

cjlectronics

Thank you for the reply,

Yes, I even replaced the trimpot as I've seen these cause wierd things.  I've been thinking about what to do next and I am going to disconnect the LFO from the circuit and interject an external signal from my function generator.  Then I'll be able to isolate the LFO to see if this is causing the ticks.  My gut tells me that the problem might be an OTA going bad, but I'll approach this issue with logic before I start throwing things at it.

Thanks again!!
CJ