Dream Fuzz noise and very low output on tone bypass.

[e_man_89]

I just finished my first build in a long time. Been wanting a fuzz so I went with a Dream Fuzz.

This thing roars!, but I have a couple of challenges;
- There is a low freq oscillation that is always there and,
- when I switch to tone bypass the level drops to below the bypassed volume even with the volume @ max).

All I could find for C7 was a ceramic. Would this contribute to my symptoms?

Thanks for any help, and for a great forum and product.

 

[e_man_89]

Thanks for your reply Chuck.

Well, I changed the sustain pot to the spec'd B10k, but I still have almost full gain right off of zero. At 9 o'clock it sounds about the same as 3 o'clock (the gain control that is).

When I changed the erroneous resistors it helped the oscillation.

When I bump the body of my guitar with my hand I get a low freq. "boom" through the amp. I thought adjusting some values might help with that and the seeming excess of gain (I know that sounds a bit contradictive in reference to a fuzz).

I cannot dial in a low gain setting with this pedal. It seems to be kinda all or nothing...

 

[e_man_89]

BTW, I spent time this evening going resistor by resistor verifying values (for the third time). They all checked out.

R9 reads; yellow, violet, black, green, brown.

 

[Chuck D. Bones]

Yellow = 4
Violet = 7
black = 0
green = 000,000
brown = 1%

That 4th band would be gold for a 47Ω resistor.

 

[e_man_89]

Forgive me Chuck, my notes had a "G", it is in fact gold rather than green.

Sorry.

 

[Chuck D. Bones]

It is my opinion that the SUSTAIN pot should be A-taper. B-taper crowds the bottom end of rotation and that may well explain the "all or nothing" behavior you're observing.

 

[e_man_89]

Thanks Chuck, I appreciate your time.

I had actually wondered about this. I checked other schematics here and there, but all had essentially the same pot value shown.

I've got an A100k. It's certainly worth a try.

I'm annoyed by the nature of this problem. So many others have built this one and don't have any troubles with it. I've checked the component values and solder joints repeatedly (as well as changing op amps) and find nothing indicating a problem.

I'm starting to think I have 1 or more faulty component.

 

[Chuck D. Bones]

Don't use A100K, it's too large and won't solve the problem. Before you change any parts, let's make a few measurements. Check the DC voltage on IC1 pin 7 and on IC2 pin 6 with no signal, then report back. It does not matter how the knobs are set for this test.

 

[e_man_89]

10:4 Chuck. Thanks for your thought and energy on this.

I'll try to get to it this weekend. Got some other stuff going on...

Stay tuned, I'll report back.

Thanks.