Home Forums GuitarPCB Build Support Super Sonic Gain Control Not Working

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  • #16716
    Paul Eliasson
    Participant

    Hello all,

    I am a first time poster but not a first time pedal builder though I started in March. I am building a tandem pedal that houses the G-02 Animal and the Super Sonic. The G-02 works just fine but the Super Sonic has a low output signal and the gain control does not function at all. I bought a second board because I had this same issue with the first and thought it was a bad B50K pot on the drive. I managed to damage that de-soldering but the same issue cropped up again with the second. I was sure to take readings to ensure the pot was functioning. Could it be bad diodes? Any help with this would be greatly appreciated.

     

    #16719
    Barry
    Keymaster

    The first thing I would do is reflow the solder joints at all the potentiometer pads and any additional pads that look questionable while you are at it. Keep a small bit of solder handy to add where needed when you reflow. Reflow any suspicious off board wiring as well.

    Be sure nothing is shorting out before you retest. For example the Jack above the G-02 is very close to the board when you plug in the guitar cable. Check other areas though so nothing is touching the enclosure or ground.

    #16723
    Paul Eliasson
    Participant

    Hi Barry,

    I reflowed all the solder to the pot pads. While the jack above the G-02 is close, it has sufficient clearance over it so it does not make contact. The same issue with the Super Sonic persists however, even when taken out and isolated. There is a little bit of a volume boost when engaged; the volume and tone controls work but the drive control does nothing.

    #16734
    Cybercow
    Moderator

    From what I can make of things based on the photos, I’m concerned over the output of the Animal PCB going directly to the stompswitch of the SS-02 stompswitch. It also seems that the input jack goes directly to the Animal PCB input point instead of the Animal stompswitch. Based on my experience, the output of the Animal PCB would go to the Animal stompswitch and the jack output of the Animal stompswitch would then go to the SS-02 stompswitch jack input point. What wiring guide did you follow?

    To be perfectly frank & honest, the stompswitch and board wiring does not look right. It’s quite difficult to tell because most of the connection wires are the same color. But from what I can tell, I’m quite certain the issues stem primarily from stompswitch to PCB mis-wirings.

    #16735
    Paul Eliasson
    Participant

    That is the case if for almost all the PCBs sold but the G-02 Animal has a buffer so the wiring to the 3PDT differs. I followed the wiring guide on page 4 of the PDF of that guide.

     

    I even isolated the Super Sonic and the same issue persists with the gain pot not working.

    #16736
    Cybercow
    Moderator

    Do you have and\or used an audio probe? I’d use an audio probe to isolate at which point the audio volume drops. It could be the pot itself or some component near it.

    #16737
    Paul Eliasson
    Participant

    I don’t have nor have I used one. There are a couple available at my local hardware store. I’ll give it a shot and see if anything turns up.

    #16738
    mybud
    Participant

    Have you checked that lug 1 of the pots (LHS with the lugs facing you) is connected to the lug 1 pad on the board?

    #16739
    mybud
    Participant

    Sorry, I see that your pot wiring is correct. Thanks in any case; that’s a useful application for 9mm pots that’s new to me.

    #16750
    Paul Eliasson
    Participant

    After testing with an audio probe, there appear to be no dead spots. I get resistance readings from the pot so I know that is not the issue. Even with the effect isolated, all the points re-flowed, the issue persists with the gain pot having no effect. This is also the second Super Sonic I wired with the same, exact issue.

    #16761
    Tom Lambert
    Participant

    Not sure if this helps & I can’t see your pics, but…  Are you sure you used an audio probe?  I rarely see those sold commercially in a store & you mentioned resistance, which makes me think maybe you used a multi-meter.  My apologies if I am wrong about all that.  An audio probe allows you to follow the signal from the schematic and possibly find a problem area.

     

    I didn’t see this mentioned so I’ll offer this: the gain pot on this pedal (assuming stock linear pot) kinda bunches the gain all at the ‘high’ end, if you know what I mean.  I think Barry suggests an anti-log pot as a mod to sort of spread out the gain.  Not sure which you used.  Are you testing with guitar volume up and the SS-2 gain pot turned full clockwise?

     

    T

    #16773
    Paul Eliasson
    Participant

    I did. I bought a Klein Audio Probe. They was only one in stock and it was locked up. I know you can make one on the cheap but I figure it would be useful for other things as well.

    I did use the stock value for the drive/gain pot, a linear 50k. I am testing the pedal with the volume and tone all the way up. There is no effect from the gain pot. I figured I would wire a logarithmic 50k pot in reverse to simulate a C50K but still, no affect with the gain pot.

     

    #16775
    Cybercow
    Moderator

    Paul – Sorry man, that’s NOT the kind of audio probe we’re talking about. The probes shown in your photos are for identifying & troubleshooting long cables runs thru buildings, server nests and phone wiring clusters. The actual “audio probe” in that tool set is a “proximity” sensor – not an exact pin-point identifying tool as in the the audio probes used in audio circuit troubleshooting.

    This is a simple audio probe for tracing a signal through a pedal circuit. Inside the white electrical tape is a 0.1µF 250v orange-drop capacitor. There are many levels of complexity for audio probes of this nature and this is the simplest. If you were to Google “guitar pedal audio probe” you will find several examples and variants of this basic concept.

    I plug in and fire up the pedal as normal (with some sort of input source like my guitar or an MP3 player), outside of the enclosure so the guts can easily be moved about, connect the gator clip of the shown audio probe to the tip of the pedal’s output jack, and then I use the tip to touch points along the audio path to see where the signal dies. With the probe connected to the output jack (which is in turn connected to a small amp), the tip will conduct any AC signal to the gator clip through the DC blocking capacitor (inside the white electrical tape).

    Whenever I have a dead or otherwise misbehaving pedal, I use this audio probe as described to help find problems. I start at the beginning of the pedal circuit – the input jack. If touch the probe tip to the input jack and I hear nothing, I know I have a signal path ground-short somewhere very near the pedal’s input. If I touch the the probe tip to the input pin of an opamp and hear a signal, but nothing at the output of the opamp, the I know I either have a bad opamp or a short somewhere very near the opamp output. Same thing with transistors, except the base is the input and the collector or emitter (depends on the circuit) is the output.

    I’ve been using this simple audio probe and method for decades and works well and safely.

    #16776
    Billy
    Moderator

    Heres a PDF Paul should explain it and it’s use etc as Cybercow says you don’t have to build a big fancy gizmo you can rustle up the one shown very quickly and get the job done

    https://drive.google.com/file/d/1T9OsJ0riQhm1QFWPfNQ5q5guikuFKDRN/view?usp=drivesdk

    #16781
    Paul Eliasson
    Participant

    Thanks for the reference PDF and instructions. I’ll give it a try tomorrow.

    Best,

    Paul

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