# Dream Fuzz Issue



## GRider22 (May 2, 2019)

Hi all,

I've just completed building Dream Fuzz and I'm getting a loud 770Hz tone coming through the output.  Using a probe it appears to start right at R5.  Anyone encounter this before and know what's causing it?  Thanks.


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## eaglehat (Jan 17, 2020)

Did you ever get this sorted? Having this same issue with mine. Haven’t started troubleshooting it yet beyond giving it a quick visual once-over and swapping the opamps. Haven’t seen any other mentions of this problem, so thought I’d check with you first.


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## Robert (Jan 17, 2020)

Make sure R9 and R17 are both 47 ohm and not 47K.


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## eaglehat (Jan 17, 2020)

Thanks for the quick reply! Looks like I got the 47ohms right.

The green chiclet 120nf I used was a tight squeeze and the corner is hovering very close to the center pin of the tone pot. Could that possibly be the issue?

Everything seems to work except for the presence of this oscillation which is always on.

(Just tried to upload a photo of the board, but the forum says the file is too big. I’ll try to resize and upload in a bit.)


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## eaglehat (Jan 17, 2020)




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## Nostradoomus (Jan 17, 2020)

Your 1uf electrolytic on the bottom left should be flipped around, best just replace it.


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## eaglehat (Jan 17, 2020)

Damn! Good catch. Thanks for the second set of eyes!


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## mikeperez83 (Dec 12, 2020)

I'm actually having this same problem on the current revision. Built it and it worked like a dream, zero issues or noise. A few weeks ago i turned it on and there's this epic squeel coming through the pedal. the effect still works, but if i'm not playing the squeel comes right back. I've changed all the electrolytics, and the op amp(which is socketed), i also replaced the 3pdt, tested it with different power supplies and the Squeel still persists. i'm about to start pulling my hair out.


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## pathom (Dec 29, 2020)

Did anyone ever solve this? I'm having the same problem, effect mostly works except for the loud squeal starting after R5 when the effect is engaged, regardless of signal input. I replaced R5 and IC1, no luck. IC1 seems to have the correct voltages (8.8v on pin 8, 0v on pin 4, 4.4v on the rest). My multimeter is reading a 60hz frequency in the signal path, so my only theory is there's some accidental crossover I can't find from the power circuit to the signal path.


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## Chuck D. Bones (Dec 29, 2020)

Does the squeal pitch change if you turn any of the knobs?  We can't read C3 or C4, make sure they are the correct values.  I do not recommend ceramic caps there, although ceramics would not cause the squeal.


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## pathom (Dec 30, 2020)

The squeal is affected by the knobs (vol changes squeal vol, tone affects tone, sustain does it's thing), although the pitch seems to stay the same.

I re-rechecked that all component values are correct and properly oriented. C3 is a 4n7 and C4 is 10n. Thanks for the tip on not using ceramics there, I'll pick up some small film caps on my next parts order for future projects.


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## Chuck D. Bones (Dec 30, 2020)

The fact that the pitch is constant tells us that the squeal is NOT caused by coupling from output to input.
Have you tried a different power supply or battery power?
Your pic shows the board out on a bench, have you tested it installed in a box?
Are you using an audio probe to determine that the squeal starts after R5?


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## pathom (Dec 31, 2020)

I've tried it in a metal enclosure, and through different power supplies, including battery and isolated psu, no change. Different amps, cables, no change. Also tried swapping the 4558 for a TL702, no change. It's a head-scratcher.

I did use an audio probe to identify where the squeal started. Could IC1 be amplifying an existing signal to create the squeal?

I think my next step will be to do a bunch of continuity testing to see if parts of the circuit are crossing over to where they shouldn't be.


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## mikeperez83 (Jan 19, 2021)

pathom said:


> I've tried it in a metal enclosure, and through different power supplies, including battery and isolated psu, no change. Different amps, cables, no change. Also tried swapping the 4558 for a TL702, no change. It's a head-scratcher.
> 
> I did use an audio probe to identify where the squeal started. Could IC1 be amplifying an existing signal to create the squeal?
> 
> I think my next step will be to do a bunch of continuity testing to see if parts of the circuit are crossing over to where they shouldn't be.


i'm having the same EXACT issue, not sure if its a board thing or not, i recently re capped and replaced the IC1 in my dream fuzz, it had been working perfectly and then one day decided it would do the same exact thing,  loud squeal, no rhyme or reason. kept it on the bench and would play through it , worked perfectly, no more squeal, plugged it in again today, same damn thing again. its the 3rd pcb i've had odd unsolvable issues with.


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## eaglehat (Apr 5, 2021)

Curious if anyone ever found a cure for this. I ended up setting mine aside after failing to identify the cause, but I see some others have had this issue since then.
If anyone has any suggestions, I’m all ears!


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