Zygote mojo

[Haberdasher]

I'm having problems.  It sounds very faint and cuts in & out when I can hear it at all.
I've been over the solder joints and I can't see any bridges so I'm trying to look elsewhere.
One of the first things I'm wondering (since I have never used axial caps or made a positive ground effect before) is if I have the caps oriented correctly.  I'm using vishay bc caps like in the pic.



The black stripe on the north end is negative I'm thinking.  Does the neg lead go to the square solder pad or do I have them all in backward?

thanks

[madbean]

The negative lead should be the squared off end of the cap (where the black band is) and positive is where the little ridge is on the opposite side. If you look at the zygote layout, you'll see that the positive end goes to the square pad. So, for example, for C1 the signal goes from the input to the pos. lead of the cap, then comes out the other side. Note that the little ridge on the cap is also pictured on the layout.

So, I'm thinking that may be your issue....caps are backwards.

[Haberdasher]

Thanks Brian, that's what I figured.  To be honest I didn't know if the little ridge on the layout represented the black stripe or the indentation.  I had a 50/50 chance and I took the wrong way, which is pretty typical for me.   

At least this should be easy to repair. *knocks on wood*

[Haberdasher]

Well I reversed the caps and it works now, BUT

a) It sounds like very farty like before if I adjust the trimmer to read .45.  I have to go up to about .58 before it starts sounding decent

b) I have to dime both pots to get much effect, and the output volume still isn't very high

Any ideas what could be wrong?

[madbean]

a) That's pretty normal. Looks like the bias point for the collector on your Q2 is a little bit higher. Really, just use you ear as a guide. Don't worry what the DMM says.

b) The output volume of a FF is already pretty low. It generally needs to get up to about 75% or higher to match the bypass signal. You can increase the output volume a little by changing R4 to 1k or 1k2. For the Fuzz pot, the fuzz will always bunch up at the very end of a 1kB pot. You can do a couple of things here if you want to alter the response: use a 1kC (reverse audio), or use a 5kB and put a 5k1 resistor between lugs 3&2 of the fuzz pot, or add an input 'impedance' control.

The last one is what Fuller calls "Bias" on the "69" fuzz pedal. The way you do it is to place a 50kB pot between the guitar signal and the input of the board. So, where you normally have a wire coming from the 3PDT that gets hooked into the input of the board you would attach it to lug 3 of the 50k. Lug 2 gets a wire to the actual input of the board. When the pot is all the way down, resistance is at maximum and it lessens the fuzz. When it's up, resistance goes to zero and you get the full fuzz effect. this can also be useful when switching between single coils and humbuckers since the buckers tend to have higher output.

It's a very simple and versatile control to have, and I do recommend it. I've even hard wired a fuzz control to have maximum fuzz and just used the input impedance to control the fuzz amount. It's a nice alternative.

[Haberdasher]

I soldered all the components to this board about 3 weeks ago at the end of a very long day and I must have been tired.  Not only were all the caps in backwards, but I also had R3 and R4 reversed!  How can I screw up when there are only 4 resistors?  LMAO

Sounds a little better now.  doh!

I've even hard wired a fuzz control to have maximum fuzz and just used the input impedance to control the fuzz amount. It's a nice alternative.

Yeah, that sounds pretty cool.  I built this thing in a junction box from Lowe's and I don't like it, lol.  I'll probably end up re-housing this one day so whenever that happens I'd like to try this.

Can you shed some light on the procedure for hard wiring for max fuzz?  Whenever you can get to it, that is.  I know you probably have a million things to do right now and I don't even have a 50kB pot here yet.  I'll be checking back later though, so I appreciate it.

[madbean]

Jumper the pads for lugs 3 and 2 and put a small resistor (1-2k) between pads 2 and 1.