Help Debug a Phase 45

[foozertone]

The problwem I'm experiencing with this pedal (built from the GGG layout with no substitutions) is that there is no sweeping motion. If I turn the trim I can get a muffled kind of phasery sound but there is no motion. Here's my readings

Batt: 10.04            Brd:9.88

Q1: G:0.87     Q2:  G:0.87
       S: 3.18           S:3.18
       D:3.18            D:3.18


IC1: 1:3.18         IC2: 1:3.17
        2:3.18                2:3.17
        3:3.01                 3:3.17
         4:0.00               4:0.00
        5:3.18                5:4.76-5.02   (It changes)
         6:3.17                6:4.95-5.10
         7:3.17                7:4.54-5.30
         8:9.84                8:9.79

I don't have the JFETs matched but I do have them as close as I can get. I've tried at least 10 specimens and I can't get the phaser going. Any help will be greatly appreciated.

Thanks

Jeffrey

[The French connection]

I don't know if it helps but on mine, the rate knob must be turn almost to his half before earing any ''noticeable'' phasing...So try tweaking the trim with the rate knob at max...But the JFET must be matched definitely.

[foozertone]

I have tried tweaking the trim with the rate knob and still got no love. I can't figure out how to build the Geo matcher... Maybe someone could give me a perf layout and part's list? I'm still pretty inexperienced and I would really appreciate it if someone could help me.

Thanks

Jeffrey

[sfx1999]

The problem is most likely in the LFO section. Can you take pictures and post them?

[foozertone]

I regretfully cannot post pictures.

Jeffrey

[sfx1999]

Does the rate knob do anything? Is it possible you connected it incorrectly?

[foozertone]

It does nothing. I switched wires and put in a new pot.

Jeffrey

[johnadon]

I don't think this is going to help you because it sounds like something's just plain not working or hooked up right. However I'd like to point out that it's possible to pick your jfets by ear in this circuit as described here under "Matching Jfets for the Phase 45":

http://www.lynx.bc.ca/~jc/pedalsPhase45.html

It worked a charm for me, plus it was kind of fun (being the noob that I am) to actually note the differences between jfets. I used j201s, and I think I got an especially good batch because the majority of the jfets worked at close to the same point on the trimmer. (Edit: Which it sounds like you are already doing. Someone should ban me from posting here.   )

(Disclaimer: I'm a noob. If you don't believe me check some of my previous posts. :-) )

[foozertone]

It doesn't really help with the fact that I'm getting no phase but I i am trying to match them by ear and I appreciate you pointing out that page.

Thanks

Jeffrey

[MikeH]

Even if your FETs were ridiculously mis-matched you'd still be getting a little bit of phase.  What you've got is the buffered clean signal because your LFO isn't working.  Every time this has happened to me (and it happened when I built my phase 45, phase 90 and CE-2) it has been 1 of 2 things:  FETs in backward (or wrong pinout) or a solder bridge causing the LFO not to work.  Double check the pinouts (don't just go by the layout- they're wrong at least half the time),  and make sure your joints are clean.

[foozertone]

I checked the polarity of the Qs and I went over my joints and fixed anything questionable and I still have no results. Maybe someone can show me where on the schematic and board the LFO resides so I can...well I don't know what I'd do but at least I'd know, right?

Thanks

Jeffrey

[oldrocker]

Is this project built on perfboard, vero PCB?  Did you make or buy the PCB?

[foozertone]

It's built on a GGG PCB. I suoulda said that before.

Thanks

Jeffrey

[foozertone]

Checked all wiring and confirmed values of components

[MikeH]

Now that I think back, when I build my 45 I had the exact same problem and it was because me FETs were in backward.  You might try flipping them around to see if you already haven't.

[plankspank]

Maybe someone can show me where on the schematic and board the LFO resides

The LFO signal is generated from the 2nd half of the dual TL072 OP amp (output signal comes out of pin 7). Check to make sure you have this oriented correctly (pin 1 is the dot on the chip.) Next make sure you have all you electrlytics oriented correctly.
     To check to see if you have an LFO signal, check it with a DVM :  set the speed pot on low, then probe Pin 7 and follow the schematic to R25- you should see the voltage fluctuate. If you have this, your LFO is probably O.K.

[foozertone]

Success! I finaly figured it out. It helps if you have all the components in. Ilike an ass, left out R25. Thank you all for your help.

Thanks

Jeffrey