Help with first pedal

Started by litmusik, October 13, 2015, 09:54:52 PM

Previous topic - Next topic

litmusik

Hi,

I've finished assembling my first pedal and I'm not getting any sound when hooking it up to the guitar and amp.

What I've tried already:
1. I've verified that all resistor values are correct twice.
2. I've verified the orientation of the electrolytic caps and IC twice.
3. I've scraped the flux between each solder joint three times to make sure there's no solder bridge.
4. I've double checked for cold solder joints and heated up all the pins to let the solder melt down into the joint.

Debugging Checklist
1.  No sound comes out of the amp.
2.  Name of the circuit = Arduino Stomp Shield http://www.openmusiclabs.com/projects/stomp-shield/
3.  Source of the circuit (URL of schematic or project) = http://wiki.openmusiclabs.com/wiki/StompShield?action=AttachFile&do=view&target=stomp_schematic.png
4.  Any modifications to the circuit? No
5.  Any parts substitutions? No
6.  Positive ground to negative ground conversion? I don't know what this means.
7.  Turn your meter on, set it to the 10V or 20V scale. Remove the battery from the battery clip. Probe the battery terminals with the meter leads before putting it in the clip. What is the out of circuit battery voltage? =>  It gets power from the arduino that's connected to my laptop through a usb cable.  I've verified that 5v are coming into the 5v pin.

Now insert the battery into the clip. If your effect is wired so that a plug must be in the input or output jack to turn the battery power on, insert one end of a cord into that jack. Connect the negative/black meter lead to signal ground by clipping the negative/black lead to the outer sleeve of the input or output jack, whichever does not have a plug in it. With the negative lead on signal ground, measure the following:
Voltage at the circuit board end of the red battery lead =  No battery.
Voltage at the circuit board end of the black battery lead = No battery.  I could add a battery clip if this would help.

Now, using the original schematic as a reference for which part is which (that is, which transistor is Q1, Q2, etc. and which IC is IC1, IC2, C1, and so on) measure and list the voltage on each pin of every transistor and IC. Just keep the black lead on ground, and touch the pointed end of the red probe to each one in turn. Report the voltages as follows:

IC1
---
P1 = 2.52
P2 = 2.53
P3 = 0.93
P4 = 5.04
P5 = 2.5
P6 = 2.51
P7 = 2.51
P8 = 2.69
P9 = 2.52
P10 = 2.51
P11 = 0
P12 = 2.56
P13 = 2.61
P14 = 2.61

Thanks in advance

PRR

IC DC voltages are about correct. (The low voltage at P3 is explained if your meter is about 1.7Megs input loading; the right-volts at P1 confirms that P3 is correct when you are not poking it with the meter.)

P8 looks high. This could be explained if PWM_H is not-quite half supply voltage. PWM_H comes from an off-board source, I assume a CPU. The 0.2V DC "error" is not your problem.

If you get NO sound, even with MIX turned counter-clockwise, there's only two stages: G$1 and G$4. As their DC is correct, and you have looked for mistakes, the most likely fault is mis-connection, possibly at IN or OUT jacks. (Confusing Tip and Shell is popular on 1/4" jacks.)
  • SUPPORTER

litmusik

I had the in and out jacks wired wrong.  I feel silly, but I also feel glad it's working now.

Thank you!!

PRR

> I had the in and out jacks wired wrong.  I feel silly

NOT SILLY!!

Everybody with any long experience has done it.

Why I mention it when I don't know how experienced a poster is. Make the "silly" mistakes, resolve not to do them TOO many times, and move on to more complicated mistakes.
  • SUPPORTER