# Sour Grape issue..



## quazimoto (Mar 21, 2019)

Greetings! I recently finished building the Sour Grape. Signal in bypass works fine. Sadly I forgot to test the board before putting it in an enclosure. When the effect is engaged there barely any sound. In order to hear anything I have to have "Buzz" turned all the way up and it is still extremely low volume. Volume and Tone do nothing. I was assuming it was something grounding out. I removed everything out of the box and still same issue. I used a jewelers lope and went over the whole board front and back to look for any poor connections or things touching and found nothing. Double checked the component values and orientations. Re-seated the Op amp as well to make sure I didn't bend a leg under. Still no luck. Any ideas on where the problem is would be appreciated! The voltages from the op amp are as follows:

pin 1: 4.58v
pin 2: 4.58v
pin 3: 4.33v
pin 4: 9.17v
pin 5: 3.7v
pin 6: 4.58v
pin 7: 4.59v
pin 8: 4.51-4.6v
pin 9: 4.59v
pin 10: 4.57v
pin 11: 0 v
pin12: 4.59
pin 13: 4.59
pin 14: 4.59

A few pics of the board:


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## Robert (Mar 21, 2019)

Is it at all possible that you are confusing the Volume and Buzz controls?    

It would be very unusual for the volume control to have no effect at all.   (not impossible of course)

Also, I noticed your pots don't have covers.   The back of the Tone pot isn't touching the PCB by any chance is it?


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## quazimoto (Mar 21, 2019)

Thanks for the quick reply! The tone pot does have a cover. The B100k is what I am referencing as the Buzz (left in pic) and the A50K as volume( right in pic). I know it looks cramped but I did verify that the the jacks are not touching the back of the pots or anything else. I double checked by removing everything from the enclosure and testing the unit.


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## zgrav (Mar 21, 2019)

I suggest leaving it out of the box until you get it working.  Seems like it is time to check continuity for your parts using a DMM and the circuit diagram in the build documents.   You might also want to google how to build a simple audio probe that will let you check the audio as it goes through the circuit to find out where it is getting choked.


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## music6000 (Mar 22, 2019)

Just Confirming, Are the clipping Led's  polarity correct. Is your Yellow wire to PCB *IN*, Green wire to PCB *GND*, White wire to PCB *SW* & Blue to PCB *OUT *from Left to Right, confirm No bridging of solder between Wires.
Hard to confirm in Photo's.
As it is out of the Enclosure, Study the Solder side of the board with magnified image and check for any bridging again of solder joints.
Other option would be to Connect In & Out jacks directly to PCB to rule out Footswitch. Make sure both Jacks are Ground to PCB.
Did you try another Op Amp?


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## quazimoto (Mar 22, 2019)

zgrav: I will try the audio probe.

music6000: The clipping LED's are correct polarity and will light up/flicker when I turn the Buzz all the way up when I start to hear sound. I did try another op amp. The wires as you described are correct. Both jacks are grounded to the board as shown in the build doc. I will have another go rechecking the board for stray solder.

Thanks for the help gentlemen!


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## zgrav (Mar 22, 2019)

Given that you see activity in the clipping LEDS, the odds are pretty good you have either a poor connection or a short in the part of the circuit between the clipping LEDs and the output.    use your circuit diagram in the build docs as a guide, and check the wiring from the output jack to the switch, then from the switch to the out pad on the pcb, then make sure the middle post on the level connects to your output,  and that post 3 on the level pot connects to c15, and c15 connects to the middle post on your tone control.  you have two different paths from your IC to the tone control that you can check after that, but you're likely to nail the problem before you reach that part of the circuit.


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## quazimoto (Mar 25, 2019)

Thank you gentlemen! Was able to get it working. Did not get a continuity reading between the middle lug on the volume and the output on the board. Tried reflowing the solder but it's possible I burn the pad or something else. Just used a jumper wire and everything work s fine.


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## zgrav (Mar 25, 2019)

congratulations on getting the board working!


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