Causality 4 MkII phaser help

Started by canman, February 18, 2014, 05:30:38 PM

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canman

Hey guys (again...)

I built up the Causality 4 phaser and I've been looking at the huge 20 page thread and thought it might be better to just post a new simple thread for my question, but let me know if it would be better to post in the huge thread.

So, I've recently built up this phaser, and I'm getting full guitar signal through it.  The problem is that I'm not getting much, if any, phaser effect.  I followed this layout: http://3.bp.blogspot.com/-yV7l2AivOY4/T0uqfbQzS5I/AAAAAAAAA4A/-AuRqY2LrjQ/s1600/Causality%2B4%2BMkII.png and here are my voltages for the IC's:

LM13700
1: 1.16-1.22
2: 0
3: 3.8-5.4
4: 3.8-5.5
5: 4.5-6.5
6: 0
7: 4.7-6.6
8: 3.8-5.5
9: 3.8-5.8
10: 4.5-6.5
11: 9.4
12: 4.5-6.5
13: 3.9-5.6
14: 3.8-5.4
15: 0
16: 1.2

TL074
1: 3.9-5.6
2: 3.9-5.6
3: 3.7-5.3
4: 9.4
5: 3.6-5.4
6: 3.9-5.6
7: 3.9-5.6
8: 3.9-5.6
9: 3.9-5.6
10: 2.2-3.2
11: 0
12: 3.8-5.4
13: 3.9-5.6
14: 3.9-5.6

TL072
1: 1.37
2: 3.6-6.4
3: 3.3
4: 0
5: 3.6-6.01
6: 3.6-6.01
7: 3.2-6.7
8: 9.4

As you can tell, I had to use a couple different IC's in place of the ones listed in the schematic.  Also, the pot values and tapers I am using are not quite the same as listed in the layout linked above.  For instance, for the 100k lin pot, I'm using a 250k log pot with a resistor wired across lugs 1 and 3 to cut the pot value down, closer to 100k.  I did the same thing for the 10k pot...it's a 20k with a resistor.  The 470k has a 500k log in its place.  Stuff like that.

So what happens when I turn the knobs is I can hear the phaser effect, but it doesn't happen automatically if I don't turn the knobs.  Technically it does, as I can occasionally hear the phaser "turn around" if you know what I mean.  It doesn't happen often though.  When I was measuring the voltages for the IC's, getting a voltage cycle for each pin took quite a while, 10 seconds, maybe 15 or 20.  Wasn't timing it, but it took longer than it seems it should have taken.  I have the indicator LEDs wired up as per the layout, but they don't seem to flash back and forth.  They both just kind of seem...on.  No shifting really, unless I'm turning the knobs.

Anyone here have any idea what is going on?  I've checked all my resistors, I've checked for solder bridges...everything looks good.  I'm wondering if the wrong pot values are to blame here?  Seems like they shouldn't be causing the issue, but what do I know.  I appreciate any and all help!

canman

OK found the problem, I had a wire connected to a wrong hole...got it working!

Next question though, it adds a bit of distortion to my clean signal.  Is there any way to add some kind of gain control to the circuit?  I'd love to be able to tune out that extra bit of gain and keep it a really clean signal.  Is this possible?