@cybercow
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Double-check the voltage at the “VB” point – where R23, R24 & C18 meet. If that value is not exactly ½ of the voltage supply, goofy things can happen with the gain pots.
Doesn’t make any sense to me. The green wires are going to lug #1 on the pots and to the #1 spot on the PCB. ??????
Double check the continuity of ground on all your cords.
After that, I’d continue troubleshooting by just plugging in the pedal to the amp and power up the pedal – no input cable or guitar to the pedal. Make sure there is no hum when the solo pedal is engaged or bypass. If it hums there, try a new cable between pedal and amp. If fresh cable doesn’t solve the hum (if it’s there), then there is an open ground somewhere in the pedal.
If no hum with just the pedal connected & powered, go ahead and plug in the guitar and check in both bypass and engaged modes. If hum, swap guitar cable. If it still hums, the problem exists with input wiring inside the pedal. Check the grounding continuity inside the pedal.
If all the pedal’s internal grounds exhibit continuity, the cables are known good, and the pedal still hums, teach the pedal the lyrics. 😉
More importantly, please let us know what find after checking the above.
Josh – yes, the value and polarity of C1 is correct in both the schematic and the circuit. I’ve built a few with zero issues. That 1M resistor to ground is there to help prevent “switch-pop” by keeping any DC on the inout side of that electrolytic bled to ground. And if you notice, on the other side of C1 there is a lower values resistor (R3 @100K) going to ground – which has the greater ground potential than the 1M resistor at the positive side. Using a non-polarized is fine. I just see no value in over-analyzing a known working circuit. Admittedly, v2 (pre-2012 version) of this circuit had the polarity of C1 reversed and was immediately fixed. Hopefully, Barry will chime in.
Peter – If the power supply was a negative center 9v & the DC supply wiring is correct – fair enough. If the proper power supply was used, then that leaves two remaining errors I can think of – that polarized electrolytic was inserted backwards or the received more voltage for which it was rated. (Can’t read the values on cap shell in the photo.)
Peter – Exploded caps happen when the wrong polarity voltage supply is applied. My guess is that a new C5 (22µF) and a proper voltage supply polarity will solve it. What did you use for the power supply?
Yves – an LM386 is a single “audio” amp and will not work in place of the specified LM358 dual “opamp”. You will need the LM358 or one of the following: LM1458, LM4558, LM4559, LM4580, LM833 or MAE2741
Good luck!
Steve – Nice job in reducing the height on those. With that small bit of clearance, I suggest adding a bit of thin insulating material, like a couple strips of electrical tape, to the inside of the bottom plate where those BJT caps “might” touch the bare enclosure casing – when completely closed & tightened up. Seeing as those BJTs are socketed, they may stand a chance of working loose a bit over time and slip downward towards the bottom plate. Cheers!
What JFETs did you use? Is there a fluctuating on either side of R23? The trimpot has a very small “sweet spot” and needs to adjusted slowly and in very small increments to find that “sweet spot”. Is the “VB” voltage ½ the value of the input supply voltage? And as Billy mentions, good clear photos are important.
If it’s a single circuit and not a combo build, you can leave out the stompswitch altogether and wire the jacks directly to main PCB “In” and “Out” points. Be sure to pay attention to the “T” (stands for “Tip”) at the respective “In” and “Out” points on the PCB – they go to the Tip on the jacks. Run the DC jack simply and directly to the positive and negative respective supply inputs on the PCB.
Josh – 2N5459 will not work. The Dr Phybes build requires a “matched set” of 2N5952 FETs. Also, the pinouts of 2N5459 are reversed from those on the 2N5952.
Have you tried adjusting the trimpot on the board? There is a very small “sweet spot” at which it will render the phase effect. Turn it VERY SLOWLY or in tiny increments to find that “sweet spot”.
If that doesn’t do it, we’re going to need some good clear photos of both sides of the build and all the wiring connections. It would good to know that you’ve measured the voltage supply and are using the correct voltage.
To be brutally honest, the wiring looks quite unstable. The insulation needs to butt up against the PCB where the wire goes thru the PCB. I can only guess that all the exposed bare wire is coming into contact with the edges of the enclosure – based on the photos.
There is an “Insert Image” icon in the posting toolbar. It looks like this . . . . .
Click that to post the images right in your post.
Increasing the value of C7 In the Ludicrous Speed should open up the bottom end of the tone, but not necessarily diminish the highs. The values of C6 or C1 could be toyed with (reduced in value) to make it less bright. Don’t be afraid to experiment.
