Need help on 1st build GGG EF-440 Envelope Filter

Started by feedthemule, August 09, 2012, 11:58:02 PM

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feedthemule

This is my first build and I'm stuck.  I could really use some help. 
Here is the background information on the build:
1. What does it do, not do, sound like: I get sound in bypass mode, but when effect is engaged, zero sound.  LED is functioning when engaged
2. Name of circuit: EF-440
3. Source of circuit: General Guitar Gadgets
http://www.generalguitargadgets.com/projects/19-filters-envelope/119-dod-440-envelope-filter?phpMyAdmin=78482479fd7e7fc3768044a841b3e85a
4. MODs: No
5. Substitutions: No
6. Positive Grnd to Neg Grnd conversion: No
7. Battery test: 8.22
   Voltage at board, red lead: 8.17
   Voltage at board, black lead: ?? battery negative goes to Input Jack Ring...
IC1
Pin1: 0.61
Pin2: 1.5
Pin3: 1.44
Pin4: 0
Pin5: 5.32
Pin6: 3.95
Pin7: 7.62
Pin8: 8.23

OC1
Leg 1, connected to L2: 1.44
Leg 2, connected to R14: 0
Leg 3, connected to R9: 5.96
Leg 4, connected to R10: 6.25
Leg 5, connected to R10: 6.32

D1
Anode: 0
Cathode: .04

D2
Anode: 1.36
Cathode: .04

C3
(-) .02
(+) 0.6

C4
(-) 0
(+) 1.36

C5
(-) 0
(+) 3.86

Other readings:
PC board
G: 0
1: .06
R2: .04
L: 1.96
9v: 8.15
O: 0
L3: 4.6
L2: 1.36
L1: 0.9

Thanks for your help!
Dan

PRR

Did you buy the board, make it yourself, or perf-board it?

Inspected under a bright light for solder-bridges, dubious joints, or other spoilers?

One opamp is stuck high, the other is stuck low. There's an awful lot of parts in between. Nothing is jumping at me.

The path shown in red-purple should all be half-voltage, 4.4V. Clearly it isn't: IC1 pin 3 is way low, IC1 pin 5 looks high. Can you follow these paths and report the voltages by letter?

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feedthemule

A: 3.69
B: 2.29
C: 0.79
D: 0.68
E: 3.52
F: 7.16
G: 4.9

Here are some images of the board.  You can see my attempt at fixing a broken trace between R2 and R1 and IC1 pin 2. 


PRR

I read the voltages as a lot of leakage in C1.

> attempt at fixing a broken trace between R2 and R1 and IC1 pin 2

C1 connects to R1 connects to R2 and pin 3 of the IC (I think). I can't make out the small images but if this is wrong it needs to be re-repaired to match the schematic.
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feedthemule

You're right it's line 3
Should I begin by replacing c1?
Could I substitute any other value or type of cap?

PRR

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