Aron Nelson fuzz face alternative layout cutting off sound

[alceuscardoso]

First sorry for my bad english.

This is the video i recorded to show the problem.
https://youtu.be/1F7S8o3rwC8

This is my first diy pedal and i am a newbie in eletronic.

The first time accidentally connected the 18v output of the power supply. It was a great sound .
When i realized, I connected in the correct output 9v, but the sound was like that. When I turn on the compressor ( Marshall ED- 1 ) sustain gets stronger, but still in strange sound at end.

Fuzz Face layout used http://www.aronnelson.com/gallery/main.php/v/DRAGONFLY-LAYOUTS_0/album18/album144/SILICON_FF_VERO_001.gif.html

I don`t know if 18v damaged some component.

Power supply output = 9.35

Q1
C = 9.05
B = 8.05
E = 8.84

Q2
C= 9.26
B= 9.05
E= 8.84

please someone could help me where to start to find the problem ?

[Cozybuilder]

Post clear photos front and back of your circuit card. Your emitter voltages make no sense. We can make wild guesses, but to really help we need to be able to look at what you actually built- there is a mistake in there.

[PRR]

Welcome.

When "all" your voltages are up near 9V, then there is a missing ground connection. There has to be some point near zero volts.

Your English is fine, better than most native speakers.

[alceuscardoso]

Thank you for reply.

Here are the pictures of my project.

Front


Wiring 1


Wiring 2


Back


I don`t know if i did right measure from Q1 and Q2. I put black wire from meter in negative pin from power jack and red wire in each leg from transistor. Also i did it with unplugged P10 cable. This disrupts the result?

[bloxstompboxes]

Is that a solder bridge between rows 3 and 4 down from the top on the left hand side?

[slacker]

I don`t know if i did right measure from Q1 and Q2. I put black wire from meter in negative pin from power jack and red wire in each leg from transistor.

That is correct but you also need a guitar lead plugged into the input jack, this connects the negative pin of the power jack to the ground for the circuit board. From the voltages you measured it looks like you didn't do this. Try plugging a lead in and doing the measurements again.

[Kipper4]

Stick a guitar cable in the input Jack and measure the voltages?....


Slacker beat me to it:)

[duck_arse]

also check with your ohm meter each pot pin to the pot body. we are not allowed to use those pin-rivet holes for wire solders. solder to the pins instead. also, clean between your copper tracks with a sharp blade, to remove any solder blobs that might short, and clean the whiskers of copper from where you cut the tracks.

[alceuscardoso]

Guys, following new information.

Is that a solder bridge between rows 3 and 4 down from the top on the left hand side?

No, i checked if had short. See in below picture. (The focus is terrible, but it's possible to see)

I don`t know if i did right measure from Q1 and Q2. I put black wire from meter in negative pin from power jack and red wire in each leg from transistor.

That is correct but you also need a guitar lead plugged into the input jack, this connects the negative pin of the power jack to the ground for the circuit board. From the voltages you measured it looks like you didn't do this. Try plugging a lead in and doing the measurements again.

Stick a guitar cable in the input Jack and measure the voltages?....


Slacker beat me to it:)

Now i have connected cable in input and the measures has changed.

Q1

C = 1.65
B = 0.57
E = 0.00

Q2

C = 1.03
B = 1.65
E = 0.99

also check with your ohm meter each pot pin to the pot body. we are not allowed to use those pin-rivet holes for wire solders. solder to the pins instead. also, clean between your copper tracks with a sharp blade, to remove any solder blobs that might short, and clean the whiskers of copper from where you cut the tracks.

I re-solder wires from pot now using the pins and nothing changed. (Below Picture)



I like the sound i hear, the only problem is the strange sound at end and the weak sustain.

Below a new clip i have recorded.
After solo demo i've demonstrated Compressor > Fuzz > Delay, after Compressor > Fuzz and at the end only Fuzz.

In last check i see that in project Fuzz pot is log but i used a linear. I see in this site (http://turretboard.knucklehead.dk/wp-content/uploads/2012/05/Fuzz-Face-NPN-BC183L-revision1.pdf) a similar layout using linear pot fuzz.

Can linear pot cause this problem?

Can transistors are not good?

[PRR]

> Q2
> C = 1.03
> E = 0.99

You have a wrong resistor value.

1K pot must be 800 Ohms to 1.2K.

8.2K must be 6K to 10K.

One popular error is a 10K where should be 1K.

Another is 82K instead of 8.2K.

I have learned not to trust my eyes, or my brain.

Disconnect all but one lead of a suspect resistor/pot and use your Ohm Meter.

[alceuscardoso]

I check resistor using a meter and i got follow values.

R1 - 324 ohms
R2 - 33.1 k
R3 - 8.2 k
R4 - 97.5 k

Can resistors be measured unplugged from DC and input cable, right?

For C2 i'm using a 10n, is it the same thing?

For C1 and C3 i'm using 50v and the projecto specs 16v, can be a problem?

Can R4 and Q1B, R2 and Q2C or R4 and Q2E solder bridge cause this problem?

[PRR]

Did you measure the pot resistance, end to end?

I don't care about caps. Your DC voltages are wrong, and that's not caps.

[Electric Warrior]

Looks like a bias problem. Try higher gain transistors, especially for Q1.

[alceuscardoso]

Did you measure the pot resistance, end to end?

I don't care about caps. Your DC voltages are wrong, and that's not caps.

Pots measure result:

Fuzz: Min = 3 ohms, Max = 975 ohms
Volume: Min = 6 ohms, Max = 542 k

Without wanting to abuse your goodwill, but you said the problem is in C and E from Q2. Considering 9.35v passing from R1
to R3 before Q2C, which is the right volts value after R1 and before R3?

Same question about before R4 (before Q2E).

Looks like a bias problem. Try higher gain transistors, especially for Q1.

I don't have more BC108A. Can i replace with a BC108B?

[Electric Warrior]

Looks like a bias problem. Try higher gain transistors, especially for Q1.

I don't have more BC108A. Can i replace with a BC108B?

Of course, the letter indicates the hfe bucket. BC108B should be higher gain than BC108A. And you can go even higher than that. Dallas Arbiter used BC108C in the Fuzz Face for years.

[alceuscardoso]

Must i place higher hfe on Q1 or Q2?

[Electric Warrior]

A higher hfe for Q1 should bring up the voltage on Q2's collector a fair bit, but it may be best to swap them both. If you prefer Q1 and Q2 matched or if you'd rather have one lower and one higher gain transistor is up to you. Try it all out to see which sound you prefer.

[alceuscardoso]

Hi guys,

Thank you so much for help.

I replace transistor by BC108B and now i got a sustained sound. Now Q1 hfe is 381 and Q2 hfe is 376.

However when i set fuzz pot on max i got a loud noise.

When i mount in metal case this noise goes away?

Follow new video.

[alceuscardoso]

Is it normal guitar tone don't work with fuzz? Wah pedal gets no effect too when i turn on Fuzz.

[Electric Warrior]

However when i set fuzz pot on max i got a loud noise.

When i mount in metal case this noise goes away?

I don't think it will. This happens a lot with higher gain transistors and certain board or wiring layouts. Try putting a small cap (220pf - or maybe smaller if you can get away with it) between Q1's collector and base.

Other than the noise, it does sound better now.

Is it normal guitar tone don't work with fuzz? Wah pedal gets no effect too when i turn on Fuzz.

Yes, this is normal. A fuzz pedal will produce a lots overtones. If you filter overtones from the input signal using the tone control, the pedal can make up for it.