Debugging a Small Stone V4 (similar to issue J)

Started by trotskyismyniece, July 02, 2011, 12:52:42 AM

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trotskyismyniece

So I have a V4 Small Stone, which according to GGG, is basically the Issue J with slightly different resistor values.

1.What does it do, not do, and sound like?
- signal is effected (different EQ voicing, color switch seems to change it a little), but does not phase.

2.Name of the circuit
- Electro Harmonix Small Stone V4

3.Source of the circuit (URL of schematic or project)
http://www.montagar.com/~patj/smlstone.gif


4.Any modifications to the circuit? Y or N
:'(  I did a ton of mods without checking after each one and the circuit stopped working completely... rookie mistake.  I have tried very hard to reverse them all and get it back to stock, and it's as close as I can get.

Interestingly, the stomp-switch that came with my pedal was a Carling DPDT which seems unusual for a V4.  I tried to replace it with a 3DPT wired for true bypass, but put the DPDT back with Input unbypassed as seen here http://www.generalguitargadgets.com/diagrams/switch_lo_dpdt_led_in.gif?phpMyAdmin=78482479fd7e7fc3768044a841b3e85a.

Lots of jumpers trying to fix shorts...obviously I need to look closer at that, but I don't know what to make of what's going on or where I should be looking.

5.Any parts substitutions? If yes, list them.
R1 - 100k that is connected to the input (Same value as before but 1/8 instead of 1/4)
R6 - 5.6k (same value as before but 1/8 instead of 1/4)
Q1 - 2n5088 was replaced
several .0068uF caps were replaced after FUBARing them on a failed Univibe attempt.

6.Positive ground to negative ground conversion? Y or N
- No.

7.What is the out of circuit battery voltage? = 9.87V
Voltage at the circuit board end of the red battery lead = 9.68V
Voltage at the circuit board end of the black battery lead = 0.00V

Q1 = 2N5088
E = 1.01V
B = 1.49V
C = 9.18V

Q2 = 2N5087
E = .99V
B = 9.17V
C = 9.66V

Q3 = 2N5087
E = 8.46V
B = 7.77V
C = 8.46V

Q4 = 2N5087
E = 7.77V
B = 8.45V
C = 8.46V

Q5 = 2n5087
E= 1.96V
B = 1.90V
C = 2.07V

IC1 = CA3094
P1 = 0.00V
P2 = 2.04V
P3 = 2.09V
P4 = 0.00V
P5 = 0.23V
P6 = 0.80V
P7 = 9.65V
P8 = 9.65V

IC2 CA3094
P1 = 0.00V
P2 = 2.00V
P3 = 2.08V
P4 = 0.00V
P5 = 0.23V
P6 = 0.32V
P7 = 9.65V
P8 = 9.65V

IC3 = CA3094
P1 = 0.00V
P2 = 2.00V
P3 = 2.08V
P4 = 0.00V
P5 = 0.23V
P6 = 0.79V
P7 = 9.64V
P8 = 9.64V

IC4 = CA3094
P1 = 0.00V
P2 = 1.99V
P3 = 2.08V
P4 = 0.00V
P5 = 0.23V
P6 = 0.79V
P7 = 9.64V
P8 = 9.64V

IC5 = CA3094
P1 = .066V
P2 = 7.75V
P3 = 8.43V
P4 = 0.00V
P5 = 1.95V
P6 = 0.21V
P7 = 9.63V
P8 = 8.43V