MXR Flanger Clock Bleed

[erick4x4]

I was given a vintage MXR Flanger, and I true bypassed it. I did a typical 3pdt setup with an LED that grounds the input when it is off.

However I still here a "tick" that changes with the Speed even when bypassed? I love this pedal any thoughts to help this? Should I make it so the output is grounded instead of the input grounded when bypassed? Any other ideas.

I did (I know curiousity killed the cat), play with the trim pots, but really think I got them back to where they were, but just thought I should mention that I changed that too.

Thanks!

[erick4x4]

Bump

[ADR]

I've got a late 70s (or early 80s) MXR flanger that I've been thinking of doing a truebypass to. However, I want to be sure before I tinker wih it. I've got a schem on my HD somewhere, and found this thread during my search for previous mod reports.

Sooo... has anyone successfully done this job?

BTW, I also want to save the old housing, in case I ever plan to sell it and can restore it, and rehouse the PCB in a new enclosure. I've got a couple of 1590BB's, but they are just shy of being able to fit the pcb inside (they the hammonds are a little short). Is there another brand other than hammond that would fit perfectly? What brand did MXR use? Budbox?

[GibsonGM]

Erick:
After being 100% certain your wiring is correct and there are no errors, there's only 1 other method I know of for silencing the 'tick'.  That is to find where the 9V power supply enters the board, and place a 100 ohm resistor in series with it.  Then, where the 9V and resistor meet, you place a 1000uF (approx) capacitor to ground.  Acts like a reservoir to supply the ckt when it calls for power, which may be causing the tick.  You might try this on a scrap of PCB and keep it near the circuit when you do it, to assure this will help before you get into your nice neat board!  It's worked for me with a couple of effects I've had that were doing that.  Don't know about the trim pot issues, I spose it COULD have an effect, but to me the following is more obvious.
This is often caused by a couple of things.  One being having grounds running all over the place (ground loops - more about noise than tick).  The gnds should all terminate at the same place on the PCB, then go to the input jack for switching.   Another is LFO radiation being picked up by input lines; solved by spiral wrapping the input wire with another wire, which has 1 end grounded to act as a shield.   Maybe when you went tru bypass you ran some wires around in there that are acting like antennae?  So, usually it's the chip sucking current and making a click, or the oscillation the chip is sending out is radiating into something it shouldn't.   Hope this helps!

ADR:  take a look at Smallbear (www.smallbearelec.com), he has a few different box sizes that might suit your needs.

[erick4x4]

Ok, so when I run the pedal through an external true bypass box the click is gone, which if I read everything right tells me that 1) I wired the true bypass wrong in the MXR pedal, or 2) I am getting some sort of "antanae" effect right?

[sfx1999]

That doesn't tell you anything. That completely removes the box from your signal path.

It sounds to me like you ran a wire (or wires) to close to the LFO.

[oldschoolanalog]

It sounds to me like you ran a wire (or wires) to close to the LFO.

+1

[GibsonGM]

+1

"Another is LFO radiation being picked up by input lines; solved by spiral wrapping the input wire with another wire, which has 1 end grounded to act as a shield.   Maybe when you went tru bypass you ran some wires around in there that are acting like antennae? "

Since moving wires and trying a grounded shield line are less invasive, maybe try that out first?  Get the input line away from the IC's....