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Hi All …
Relative newbie here and my first post to this forum (although I have built many kits and from scratch pedals). I just finished a Dr. Phybes with both the Script mod and the Wilkie mod.
Works great with SW1 closed (feedback) and in the Phase 90 configuration (nice lush phasing and tone with trimmer dialed in).
When I open SW1 I get some weird noises … it sounds like someone clicking their tongue at me intermittently and a slight whoosing noise also intermittent … Any thoughts on where to start troubleshooting ?
Also when I switch to the Phase 45 configuration on the DPDT switch the effect is extremely subtle (almost no effect) and not much sensetivity to the speed pot… Is this normal ? I triple checked the wiring on the switch and R10/R12 and all looks correct.
Thanks in advance,
Bob
Congratulations. You are the first builder that has reported “tongue clicking and whooshing” to me. I don’t recall Barry or other moderators reporting this either. Is this occurring when SW1 is open? If so, I have no idea what the source could be. A bad ground? RF from outside? A faulty chip? A leaky cap? Anyone else have an idea?
In the phase 45 position, there are only 2 phase shifting elements instead of 4. The effect is much more subtle. If it is too subtle for your taste, then you may wish to just use the phase 90 position. If your wiring is correct and you have adjusted the trimmer for maximum effect, I have no other suggestion.
I will mention that if you are using a 500k Pot there is a larger amount of slow phasing in the rotation so from full anti-clockwise to say 12:00 it might not sound like there is a whole lot going on because the phasing is slow.
You could try a 100k Pot instead which is my preference.
Where you put your Phase (pre or post) distortion will also make a big difference when used with distortion or fuzz.
Pre-distortion or Fuzz is much less dramatic but this is my personal preference as well.
Thank-you Wilkie1 and Barry ! Yes noise is with SW1 Open so I will check grounds. I will play around with the Pot size too. I bought this as a kit on an associated website so I used the Pot it came with which was a 500K.
Hi Guys –
Got sidetracked with some other projects and work but I’m back to troubleshooting my Dr. Phybes build. I found a problem with the mod switch (Ph90 to Ph45) and replaced it and cleaned up some of the wiring. In the process when I had it all pulled apart and was testing I managed to short the back of the board to one of the power jack solder lugs and heard a slight pop thru amp speaker.
Now I get no signal thru at all with effect on … only LED comes on (bypass works fine too). I started tracing with a signal probe and I have clean signal going into pin 3 of the TL071 op amp but nothing coming out of pin 6. I swapped in a new op amp so I think the op amp is good. It’s almost like the op amp isn’t getting enough supply voltage to do anything. Can you give me an idea of what some of the reference voltages should be at a few points I can check ?
As always any help/advice greatly appreciated ! I recently built the Paragon/Stage 3 combo you had on your mailer card and absolutely love it !
Bob
Check the voltage on D1 anode + side that may have been damaged should be 5v ish
IC1 – pins 2,3 and 6 should be the same as VB ( around 5V) pin 4 is ground (0V) pin 7 is power supply (9v). Pins 1, 5 and 8 are not used – they could vary from 0V to a few millivolts.
There’s a good chance if you’ve shorted power D1s zapped
Thanks Billy ! Good call. Sorry to just be replying but I did not have any more 5.1 volt diodes on hand so had to order some. Just replace and the circuit is working now.
Bob
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