What Does the Foxx Phase?

[DMgremlin]

I can definitely get more pics and will update progress. 

The voltages "seem" to be correct all over the place...9V, 6V, and 1.8V everywhere it should be.  The gate and drain voltages of all the FETs match each other, and the source legs all seem to hover between 5.5-5.6 volts or so...will hafta double check those readings, going off memory. 

The threadle pot smoothly measures between about 1k-70k with no weird jumps.

The IC doing the LFO has swinging voltage (between ~1-3 volts if I recall) on the output pin. 

The mode switch and rotary speed switch don't seem to do anything at all...no audible click or effect to the non-phasing output signal that does get through the pedal. 

The Q knob does increase bandwidth (or volume anyway?), sounds a little louder with more perceived bass content.

Again I could be wrong and hafta check again, but possibly Z2 pin 9 (inverting input) did not have audio with a probe...and was thinking it should.

.......

I recapped all the electrolytics with new ELNA audio grade 10uF's throughout, and the 220uF filter cap with a new one.  I may replace the 6M8 carbon comp with a metal film just for posterity.  I have a 180p silver mica I can swap the ceramic with, not that it ought to, but that cap looks seriously funky and I don't happen to have any ceramics in that value.  I am going to add the pulldown resistor at the input and 100n cap on the feedback loop to get rid of switch pop, because it's definitely a loud pop! 

I already have a brand new set of LM324N's and a bag of J112's in case the opamps or FET's end up needing replacing.  You would want to assume a transistor failed but right now I don't see it.  Only had a short time with the unit, and no time on the scope yet.  I'll be excited to get this up and running as it was always a bit of a white whale for my personal collection!

[DMgremlin]

Got it fixed!

Basically there were a couple suspect/bad solder joints, and the speed caps for the rotary needed replacement.  Then reset the FET bias trimmer to factory calibration.

I added a series 100n decoupling cap and resistor to ground (where the feedback loop connects to the pedal switch) to prevent DC at the output jack.  So it still has all the stock IC's and transistors!  Now I just need to clean up the treadle pot internally (or replace if track is worn thru) and it's 100% good to go.

Personally, I think the longest phase time should be MUCH slower and I could probably put a larger cap there, but leaving it all stock values for now.  I have a Small Stone that I added an ultra slowwww speed mod for that type of sound anyway...

Anyway, just reporting the successful repair!  If anyone needs new gutshots or help with one, you know where to find me.  - GREMLIN

[nickbungus]

Brilliant.  Well done.

I'd love to see the gut shots please.

Do you know what year this model is from?

[DMgremlin]

Sent you a link to pics, Nick.  I will hafta investigate further for possible date.

[nickbungus]

Thank you so much

[bcruzin2]

Finally had a chance to box up my Foxx Phaser. I added a KAT (Knight Audio Technologies) treble booster http://www.deacyamp.com/index.php?route=information/information&information_id=12 , added a selector switch for the different cap values and since I had extra lugs added a few lower caps. I left holes on the box debating if I want to add a "deep" switch adding 100nf for c16 and c21 and a hole as soon as I figure out how to add an led for lfo speed.  Any suggestions for that?

[bcruzin2]

I forgot I had this handy little circuit from another discussion in this forum Connected it pin 7 of ic3