Debugging help: Ross Phaser

Started by Kinetic, May 16, 2010, 04:14:08 PM

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Kinetic

I've been working on this one on/off for a few days now and I'm not having any joy.
I've built a Ross Phaser on veroboard using the Tonepad layout here: http://www.tonepad.com/getFile.asp?id=99
Built very close to stock, although I have added in a toggle switch for vibrato.  I have substituted 2.2k resistors for the 1.8k ones and I've used a 0.47uF cap instead of 0.5.  IC1 is a JRC4558 and IC2 3 and 4 are all JRC 13600D.

Fine in bypass.  When engaged, there is clean signal but no noticable effect.  I know it sounds a little weird, but I have noticed that if I hold my finger against lug 1 of the Regen pot then I can hear a swirly sound through my amp which I can vary using the rate pot, so I presume the LFO is working.

Voltages:
Power supply 9.07V

IC1 - 4558
1 3.82
2 3.82
3 2.49
4 0
5 3.82
6 3.82
7 3.49
8 9.07



IC2 - 13600
1= 1.12
2= 0
3= 3.81
4= 3.81
5= 0.61
6= 0
7= 0.61
8= 1.6
9= 6.05
10= 5.45
11= 9.05
12= 5.45
13= 3.84
14= 3.81
15= 0
16= 1.12



IC3 - 13600
1= 1.12
2= 0
3= 3.82
4= 3.82
5= 0.61
6= 0
7= 0.61
8= 1.62
9= 4.43
10= 0.61
11= 9.07
12= 0.61
13= 3.82
14= 3.82
15= 0
16= 1.12



IC4 - 13600
1= 1.12
2= 0
3= 2.8
4= 1.8
5= 2.8
6= 0
7= 2.8
8= 2.8
9= 1.8
10= 3.0
11= 9.11
12= 3.0
13= 1.8
14= 2.8
15= 0
16= 1.21

Thanks chaps!

Kinetic

Just in case it's of any help, I've just wired an LED up to IC4 to check if the LFO is working, and the LED does indeed pulse and is variable with the rate pot.

Kinetic

No worries, I've got it working.  I had 1.8 OHM resistors in place of 1.8k.  I have never ordered 1.8 ohm resistors from anywhere, so I must have been sent the wrong things and I never checked the colour bands to be sure.  Just shows you how easy it is to make mistakes sometimes...