First time building Craig Anderton Tube sound fuzz... need help!

[acobberson]

Okay, I'm a first time builder so I thought I'd try my hand at the Craig Anderton Tube Sound Fuzz pedal. I got it all put together but when I plug in I find this problem... I get a signal but no matter if the effect is on or off I can't get the effect to engage. Also, no matter how I click the switch on or off the "volume" control is engaged. I assume I've got some wires wired incorrectly gonig from input to the switch and/or from the switch to the effect. Any ideas? I used a Carling DPDT switch.

[Enzo]

You said it yourself, you probably have a wiring error or poorly done connection. There is little way for us to know just what you did wrong. I would carefully go over the entire construction, verify part values and connections. For example, make sure you did not install a 100 ohm resistor where a 100k ohm resistor belongs or vice versa.

[acobberson]

Okay, I think I found it. I installed the socket for the chip upside down. The chip is right side up, but the socket is backwards.

[52 Bill]

The orientation of the socket doesn't make any difference as long as the chip is inserted in correct orientation for the circuitry.

That circuit uses a CMOS chip, that can be damaged by static discharge. Be sure to ground yourself before handling the chip.

From your first post I'd say that you have not wired the bypass switch correctly. In one position, you should have straight signal where no controls work, and one position where the effect works (or not). Double check your wiring.

[acobberson]

I've checked my wiring to and from the bypass switch. From hot input jack I go to pin 2 of switch, from pin 5 I go to hot output jack, I have pin 1 and pin 4 wired together for the bypass, and I have pin 3 wired to effect input and pin 6 wired to effect ouput.

[52 Bill]

This wiring sounds ok. When you plug in the guitar and amp, do you get signal bypass, where the guitar sound normal and none of the controls effect the signal?

In the other switch position do you get any signal at all?

[acobberson]

No, I get a "scratchy" signal in bypass mode but the volume pot still effects the signal. With the effect switched on I get nothing at all. Also, with the effect switched on I'm getting RF interferance but no guitar signal. Strange. I feel like scrapping the whole thing and starting over, haha.

[52 Bill]

Either the switch is bad, or you do have something miswired. In bypass mode, the controls should have no effect on the signal at all. Check the switch with an ohmmeter and double check all of your wiring.

[frank.clarke]

Audio probe the signal path to see where the sound cuts out. The chip pins in the signal path should be around half the supply voltage.
Your bypass wiring is wrong.

[acobberson]

What should the switch read at if it's a good switch? And thanks for all your help.

Either the switch is bad, or you do have something miswired. In bypass mode, the controls should have no effect on the signal at all. Check the switch with an ohmmeter and double check all of your wiring.

[52 Bill]

What should the switch read at if it's a good switch?

Look at the terminal side of the switch, and align it so that it resembles the number 6 side of a die (two columns across and three down). I don't know how you numbered the switch terminal before, but for this test follow my numbering scheme.

Call the upper left hand terminal #1 and the upper right terminal #4. The left middle terminal #2 and the right middle terminal #5. The lower left terminal #3 and the lower right terminal #6.

#1 #4

#2 #5

#3 #6

Set your meter for ohms or continuity. Attach one lead to terminal #2 and attach the second lead to terminal #1. Your meter will either read 0 ohms or infinity. Activate the switch push button and if the switch is working, the meter will read the opposite of your original reading. Push the button again and the meter reading should switch back again. Now test between terminals #2 and #3. You should get the same type of results. The wiper connects terminal #2 to terminal #1 in one position and to terminal #3 in the other position.

The same is true for the second column of terminals. The wiper connects terminal #5 to terminal #4 in one position and to terminal #6 in the other position.

[acobberson]

cool. That makes sense. Thanks for all your help everyone. This can be a frustrating experience but it's good to know I can get tips and help. I'll test my switch this weekend. I'm going take everything apart, except the board, and rewire everything very carefully, and check my connections on my board too. Hopefully I'll get this thing working shortly. I'm also toying with the idea of putting a resistor to groud after the first cap from input. I've heard that this can help reduce RF interferance. What do you think?

[acobberson]

How should I change the bypass wiring?

[52 Bill]

If you follow the numbering scheme in my earlier post, connect #1 and #4 together. Wire the input jack to #2. Wire the output jack to #5. Wire the input to the FX to #3. Wire the output from the FX to #6.

As for the input resistor, wait until you have the fuzz working and see if you have a problem with rf interference, before you start adding things.