Fuzzrite clone Schematic help!

[albertozioli]

Hi bill, I am posting some more pictures, I changed the resistors for the 4 bands, and I used the multimeter to check is showing 468k, I think that is everything ok, I checked many times, the effect give me gain but with a little bit of Distortion (weak distortion)... do you know what is happening? maybe is the capacitor that I'm using 0.047 instead 0.05, what do you think? Thank you very much for helping me again...

Regards
Albert

[Mr. Bill]

Don't worry about the value of the caps, 0.047uF is the modern equivalent of a 0.05uF cap. This will not cause your problem.

If you turn the Fuzz control fully counter clockwise what signal do you get? I'd expect a fairly clean sound with a little odd distortion, especially with the bridge pickup.

When you turn up the Fuzz control, does the sound get louder and more distorted?

Do you know how to test the transistors with your meter?

Edit:
I just examined your new photos. Please check that the green cap in the middle of the board connects the collector of the first transistor with the base of the second transistor. It looks like the jumper on the right side of the cap goes to the buss that connects to the collector of the second transistor.

[albertozioli]

I checked the jumper and looks like it's correct, I think on the 4th picture of the second post you can see it, if not I can take more pictures and post them.

I don't know how to test a transistor with my meter could you explain it to me please!?!

Yes, it has a fairly clean sound with a little odd distortion when the fuzz controll is on maximum.

Thank you!!!

regards.
Albert

[Mr. Bill]

I checked the jumper and looks like it's correct, I think on the 4th picture of the second post you can see it, if not I can take more pictures and post them.

This is why I asked, the jumper looks like it goes from the cap to the third row buss, which looks like it is connected to the collector of the second transistor.

If your meter has a diode test position, use it. If not then use a low resistance scale. Touch one lead (red or black) to the base connection of the transistor. Take the second lead and touch it to the emitter. You should either get a low reading or a high reading (maybe an infinite resistance reading). Next take the second lead and touch it to the collector. Again you should get some sort of reading. Make note of your readings.

Now reverse the two leads. If you started with the red lead on the base, switch it to the black lead. Now touch the second lead to the emitter and the collector again. Your readings should also reverse from the first test. If you got a low reading from B to E with the red lead on the base, then with the black lead on the base you should get a high reading from B to E. Repeat for the B to C test.

As a final test take a reading from collector to emitter. Test it both ways.

In any case with the NPN transistors that you are testing, you should not have low readings in both directions (polarities) between any two terminals. You should get a low reading from B to E and from B to C with the meter attached in one way and a high reading with the meter leads reversed. The connection from E to C should be high with either lead hookup.

[albertozioli]

This is what I got:

Black lead on the base:

1st Transistor:
B + E = 0
B + C = 0

2th Transistor:
B + E = 0
B + c = 0

Red Lead on the base:

1st Transistor:
B + E = 752
B + C = 743

2th transistor
B = E = 742
B + C = 732

Emitter + Collector:
Transistors 1st and 2th
Both of the leads= 0

What do you think?
Thank you!

Albert

[Mr. Bill]

Those figures seem to show that the transistors are ok.

Did you double check the jumper that I asked about?

[albertozioli]

Yes I checked it and it maches the schematic that I have, but I have good news, I tryed a pot with 1m instead 100k and now it is making a fuzz sound, but the fuzz doesn't have much sustain, what do you think that it is? the transistor? maybe other NPN would be better... What is your opnion?

Cheers!
Albert

[Mr. Bill]

I've used pots up to 2 meg for the fuzz control, but the value of this pot shouldn't shouldn't be the cause of your problem.

The gain of the transistors could make a difference, but a typical BC108 should have enough gain. Maybe just a bad transistor.

If you can't get anything else to work right, as a last resort, try taking the output signal directly from the 2n2 cap coming off of the first transistor. Check to see what does the signal sounds like there. Then input the signal into the 2nd 0.047 cap and take the output from the second 2n2 cap. Check the signal from there.

[albertozioli]

Hi bill, today I think that I am really close to finish my project, I changed the 2 resistor 10k for the 470k, and the fuzz sounds good now, well I think so... hehehehehe... (I don't know, some of this schematic has this 10k resistor and others don't, for me teh schematic with 470k it worked well) other thing that I did was put a resistor from the fuzz attack (3 pin) to the ground and made a good difference, other thing as well that I'm doing now is biasing the transistor, I just used a pot instead the resistor 470k from the base to collector of the transistor, with the pot now I can measure what is the best resistor to put there or... just keep with the pots as more options to control it....

What do you think?

Do you know any other thing that could I do to improve? maybe other transistor, what is the best transistor to work with?

cheers!

Albert

[Mr. Bill]

Good to hear that it's working better. My personal favorite value for the collector resistors is 470K, which I believe is the original value. As for transistors, I use whatever I have handy 2N3094, 2N3391A, TIS98, etc.

Tweaking the values with a pot will let you get the best sound with the transistors that you have. This is the best reason for building a pedal yourself, as it allows you to get exactly the sound that you want.

Sometimes I will use higher values for the fuzz pot. This allows you to get a different mix of the clean and distortion signals. At some settings, you can get a sitar like sound, octavia octave-up sound, a kazoo like sound similar to Hendrix Crosstown Traffic (where there is a clean note accompanied by a fuzz sound), and a complete all out distortion sound.