Home Forums GuitarPCB Build Support PUFF BUILD HELP

Viewing 17 posts - 1 through 17 (of 34 total)
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  • #22439
    Chad Law
    Participant

    HELP!!!! Just finished the PUFF build and the lights on but no ones home! lol Hooked it up solo to my amp and the green bypass light comes on as does the red effect light but no sound comes out… When adjusting the bias i noticed the pot doesnt really do much , voltage is at -8.76 on the low and -9.08 on the highest setting.

    #22443
    Barry
    Keymaster

    You will get a lot more response if you post clear pictures so we can see what is wrong with your build 😉

    #22444
    Chad Law
    Participant

    Here’s some pictures of my build, the true bypass is not working either.

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    #22446
    Billy
    Moderator

    Your in jack tip looks to be wired to ground on the 3PDT board try swapping the red and black wires on the jack

    Also can’t really see but is your white wire going from the main pcb ground to a 9v pad on the 3PDT board

    #22448
    Chad Law
    Participant

    Thanks Billy! A fresh set of eyes is always a good thing. Fixed that now I have a new issue.. In bypass mode with the led green the effect is on but sounds like very broken static and the volume and fuzz pot work in reverse..  i.e. volume at 10 no output, volume at 0 fizzy broken crackle. Same with the Fuzz pot. Could the 3pdt switch be in backwards??

    #22450
    Billy
    Moderator

    3PDT looks fine Chad

    If you’ve placed the LED as shown in the build doc green would be effects mode, red bypass

    Did you bias the collector of Q2 to around -4.5v to -7v

    The pots I don’t understand looking at the V5 PCB lug 1 is the square pad to the left so as far as I can see if using pcb mounted pots your pots look wired correctly

    The only reason they’d work backwards is if the 2 outer lugs were reversed if you’ve used wire swap the 2 outer lug wires on the pot lugs ie desolder at the pot lugs and not pcb pads to avoid heat damage to the solder pads and swap the wires around

    #22453
    Chad Law
    Participant

    I did use wires from the pcb to the pots, I’ll swap the 2 outer wires later today. As far as biasing the Q2 transistor.. I tried and the lowest voltage it will get to is -8.76vdc the sweep of the bias pot is only about .30vdc. So something is not right, even tried turning the bias pot with the pedal hooked up to my guitar and it goes from very broken crackling to slightly broken crackling. No fuzz or usable effect at all.

    #22456
    Billy
    Moderator

    Your problem sounds like transistor biasing

    I’d actually read your biasing voltage but forgot you’d already given that info doh!

    The only resistors I can’t clearly see the colour bands on are R2 and 3, double check R3 value is 330 to 470 ohms and solder joints are good

    I can’t really see what R3 is

    R2 isn’t too clear either should be orange orange black red brown

    #22458
    Barry
    Keymaster

    @ Cybercow. His orientation is correct if he had used on-board potentiometers.

    We have since updated the PUFF v5 2021 board to make good use of space.

    The Lug Number (1) for the potentiometer Lug is silk-screened on the back side to be certain.

    #22460
    Barry
    Keymaster

    While I do not think this has anything to do with the Bias issue I would switch the transistors with each other since you likely want the lower gain transistor in Q1. Looking at the datasheets these can be as high as 200 – 300 hFE and the 2n1307 being the higher of the two. Unless you tested these and found 2N1307 to be lower I would switch them.

    #22463
    Chad Law
    Participant

    Here’s a better picture of the resistors. About to swap the pot wires to see if that fixes the backwards issue.

    #22465
    Chad Law
    Participant

    <hr />

    I did swap the transistors with no change in the voltage on the collector of Q2 to ground. Exact same reading no matter which transistor is in the Q2 socket.

    #22466
    Barry
    Keymaster

    as I said the transistor arrangement won’t affect the bias however it will affect how good the pedal ultimately sounds with a lower hFE in Q1. Swapping the leads on the pots will definitely change how the potentiometers works. Lug 1 is marked with a number 1 silkscreen right beside the board pad for verification.

    From our Tip Sheet:

     

    #22468
    Chad Law
    Participant

    Alrighty so I swapped the outer wires to the volume and fuzz pots and they now work like there supposed to, which is weird cause it was wired to the spec sheet. Still can’t bias Q2 lower than -8.76 volts now I can hear the fuzz but its very faint and drops off very quickly. Is there anything else I can do to lower the voltage to the transistors?? Also notice my trim pot has the numbers 203 all other builds i see have a trim pot with the numbers 303. Could the trim pot i received be the wrong size?? Thanks for all the assistance!!!

    #22470
    Chad Law
    Participant

    also would R4 bieng 133k instead of 100k be the issue with biasing??

    #22477
    Barry
    Keymaster

    Yes you can use a 30k trimpot. That is also specified in the document and perhaps with the transistors you are using that may be required in this case? Not really right or wrong just accounting for tolerances of components is sometimes tricky

    I really need to understand and verify that you are telling me that when you wire the potentiometer Lug One (back side of pot – right lug) to the Pad silk screened Lug 1 that this works backwards for you?

    #22478
    Barry
    Keymaster

    Just saw your resistor post.

    R4 needs to be 100k. Yes that will make a difference.

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