Dr. Phybes, modulation present but no rate shift (sort of)

[Anonymous]

I’ll post some pics and video later. I am built a combo pedal featuring the Dr. Phybes.

Here’s what has got me stumbled; the effect works and I can definitely hear the effect when dialing the trimpot. However, the rate shift knob won’t work, and there is no phasing back and forth. When jiggling things around, I pushed the pcb up with my finger below Q3 and the effect worked as intended.

My assumption is I probably have a cold solder joint wherein something needs to go to ground. Does this sound right? If so I guess mynext order of business is to reflow my joints and see if it works as intended.

 

[Anonymous]

Hi Paul,

I also remember, that board has 2 ground pads and both must be connected.

I’m looking forward to the pics!

 

[Anonymous]

Thanks Fig. Both grounds are connected. Here is a video of the issue at hand.

[Anonymous]

We could use good pictures of the board (front and rear) as well as voltages on the ICs.

[Anonymous]

Well, I was going to suggest swapping the outer leads on the rate pot, at least until you moved the board. That makes me think a loose connection somewhere.

[Anonymous]

My apologies for taking so long to get back to this. Please find pics below. I reflowed my joints and everything seems to be connected solid but still get no shift unless I start touching the bottom of the transistor.

 

[Author]

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