Easyvibe Debugg

[Big Red]

1. Easyvibe ala Geofex.com
2. http://geofex.com/PCB_layouts/Layouts/easyvibe.pdf
3. PCB
4. TL062 opamps used
5. Negative ground
6. sound passes through (unvibed). the vibe/chorus switch changes tone slightly. bias leds light
   up but do not pulsate as stated at the bottom of this page http://www.hollis.co.uk/john/easyvibe.html.
   I poked holes in the heatshrink and the led/photocell leds appear to be dimly lit and when
   the depth pot turned fully clockwise they seem to go out.
   note: I am using the simpliest wrapper, just input and output jacks to limit variables.


Battery Voltage while effect engaged: 9.83 (brand new for debugging)

U1
3.907
3.907
2.037
0.000
3.900
3.907
3.907
9.81

U2
9.14
3.576
3.907
0.000
3.899
3.909
3.911
9.80

U3
3.917
3.917
3.917
0.000
3.897*
3.911*
3.908
9.78

U4
0.624
3.911
0.619
0.000
3.860*
3.870
3.847
9.77

led5  3.868 (square pad)
      2.219
led6  2.219 (square pad)
      0.575


(using diode mode on dmm)
D6 0.575
   0.000
D1 0.000
   0.604
d2 0.000
   0.604
d3 1.513
   0.528
d4 1.509
   0.532

*opamp legs with * make the sound similar to when you touch your thumb to a patch cable plugged into an amp, but there does not seem to be any shorts
additional notes: I have traced the circuit several times with an exacto knife to attempt to eliminate any solder bridges.
all parts scavenged from my last attempt at the easyvibe except the op-amps which are new   

I think thats everything

[Torchy]

From another member (spudulike) - voltage levels from a working vibe.

BTW the bias leds should NOT pulsate, they should be constantly lit. Only the LEDs on the LFO (1-4) should pulse. By the sound of yours the LFO aint working, check the component values again. I also notice youve got almost Vcc on pin 1 of U2 - this should pulse between 2.5 - 4.5 V. And you have 0.6V on the other end of R19

[GibsonGM]

I built one, had a small short to ground on the 1N914's in the oscillator section.  Worked fine after I found that, except for the annoying ever-present :CLICK: of the oscillator - used TL064's.  I'm going to rebuild the PS and oscillator on another board and monkey the 2 together to isolate them. 

This applies to your problem this way:  I learned a ton about how the EV works by audio probing...probe around the oscillator OA's (outputs of U2A, U3A, U4A, after R18).  If it works you'll hear the click.  Probably a short, is my guess....good luck!

[Big Red]

From another member (spudulike) - voltage levels from a working vibe.

BTW the bias leds should NOT pulsate, they should be constantly lit. Only the LEDs on the LFO (1-4) should pulse. By the sound of yours the LFO aint working, check the component values again. I also notice youve got almost Vcc on pin 1 of U2 - this should pulse between 2.5 - 4.5 V. And you have 0.6V on the other end of R19

hmm, as I said I rebuilt this from an old one that worked for a while, and I'm sure the bias leds pulsated when it was working.
Are the lfo's susceptable to heat damage? they're the ones Mr. Daniels reccomends for the easyvibe on his site, and they were from a unit that was once operational.
finally I'm not how to interpret your third piece of advice. none of the voltages that should be oscilating are (lfo's shot/shorted ?)

I've compared to that chart before and the voltages seemed to approximate the ones on it, but slightly less, but I was using a near dead battery. I'll try again now that I have a fresh one.

finally I forgot to mention that I fixed that infamous trace that connects where it isnt supposed to connect (which is now corrected on Geofex.com)

[John Lyons]

The bias LEDs should be constantly lit, no fluctuation.
Cut off the light sheild insulation (unless you used a comecial sealed unit) and see if the LEDs in the LEDs sections are pulsing.
If they are not pulsing then the LFO is not working.

[Torchy]

The bias leds are there to provide a steady Vb and if they are pulsing you have a problem.
I have deep concerns that you have 9v (effectively an opamp output) at one end of a 47k resistor and 0.6v at the other end. You have a short somewhere, or a fried 062.

[Big Red]

would it be safe to say the short is between U3 and U4 then? I'll start checking there and I'll fire in an opamp from the first attempt and the #4 position

I poked a hole in the heatshrink around the led/lfo's and they are lit but not pulsing