Messages

Hi there folks,

I'm into a new fuzz face fx and I was wondering why anybody has never concerned about the voltages in Q1 and then I read this topic.

What i'm really doing is trying to improve the sound of a JHF1 Fuzz Face, what I guess It won't be difficult cause it really sounds like crap. This version mounts a pair or BC108 with hfe of 228 (Q1) and 238 (Q2), and I really ignore the leakage even though it won't be high just because they are silicon trannies...

I have used this applicattion http://www.diystompboxes.com/analogalchemy/emh/emh.html proposed by Marauder, however I still don't get the voltages required in Q1 that are a must have...

According to geofex schematics, I'm using a 100k resistor as R4(feedback resistor) and the calculator says I ought to use:
R1 = 12.3k
R2 = 4.7k
R3 = 220ohms (Actually I have soldered a 820ohm resistor to have more output)

Tweaking the values a bit I get (with a 8.98v battery)
Q1:
e = 8.93v
c = 7.35v
b = 8.33v

Q2:
e = 7.98v
c = 4.58v
b = 7.36v

You will notice that the only voltage value that it is considered acceptable is the colector at Q2. What should i tweak and mod to get acceptable voltages?

By acceptable voltages in a silicon FF I mean:
Q1:
C 1.4V
B 0.6V
E 0.0V

Q2:
C 4.5V
B 1.4V
E 0.8V

HELP!

Haven't tried, but it's a good solution...

I'll give it a a try, hope it works...

Besides, I still can't explain why it sounds when the fx is engaged even though I only get noise on IC1 !

Damn thing !

I can't explain why the signal sounds through the pedal when it is switched on whereas I only get very LOW noise in pin 1 of IC1.

Anybody?

I guessed the fx won't sound unless I got sound in pin1 IC1...

Why?

Thanks Scruffie,

It is important to know that Although I've got troubles with the signal at IC1 Pin1, the FX sounds however it doesn't delay the signal nor modulate it.

The strange thing here and what I concern about is that I can't explain why I don't get any sound (only very Low NOISE) at pin 1 IC 1 when the fx is engaged but it is working. It's working because it modifies the bypass signal and I can lower it by using the level and bend pots !

The other pots doesn't work.

Pictures:





As I said... I rechecked every component and solder once !

Is there anybody out there? (very good Pink Floyd Delayed theme)


I want this one working but I'm empty of ideas. Anyone?

Thanks in advance

Ignacio

Hi again !

After a large holidays I'm here again ... I have reviewed every component, every resistor and they are all soldered in the right place. I have re-done every solder but It still doesn't work properly...

Nevertheless, the IC voltages have changed. Here is what I get (in blue the new voltages / in white the voltages i got last time i checked everything )

IC 1
1 - 5.20
2 - 5.20
3 - 5.10
4 - 0
5 - 4.73
6 - 5.20
7 - 5.20
8 - 9

IC 2
1 - 6.51
2 - 6.72
3 - 6.72
4 - 0
5 - 7.64
6 - 7.54
7 - 8.3
8 - 6.88
9 - 6.88
10 - 8.35
11 - 7.79
12 - 6.45
13 - 9
14 - 7.15
15 - 7.15
16 - 6.45

IC 3
1 - 5.20
2 - 5.20
3 - 5.11
4 - 0
5 - 5.04
6 - 5.21
7 - 5.21
8 - 9

IC 4
1 - 0
2 - 9.04 . 4.21
3 - 4.25 . 6.24
4 - 4.36 . 6.4
5 - 8.11 . 8.14
6 - 9.04 . 4.14
7 - 7.49 . 4.02
8 - 7.75 . 7.79

IC 5
1 - 0
2 - 9.04 . 4.16
3 - 3.79 . 4.43
4 - 3.87 . 4.45
5 - 8.11 . 8.14
6 - 9.03 . 4.20
7 - 7.12 . 1.29
8 - 7.75 . 7.79

IC 6
1 - 6.10 . 1.29
2 - 6.06 . 1.23
3 - 5.94 . 0.9
4 - 0
5 - 5.49
6 - 5.66
7 - 6.12
8 - 9.04

IC 7
1 - 4.38 - 5.14 (Oscillating) . 0.79 - 8.4 (Oscillating)
2 - 4.73 . 4.63
3 - 4.77 . 4.15 - 5.25 (Oscillating)
4 - 0
5 - 4.73 . 4.60
6 - 4.78 . 4.73
7 - 4.76 . 4.21 - 5.07 (Oscillating)
8 - 9.04

IC 8
1 - 5.20
2 - 5.20
3 - 5.05
4 - 0
5 - 7.59
6 - 7.63
7 - 8.35
8 - 9.04

IC 9
1 - 9.04 . 4.83
2 - 0 . 4.19
3 - 0 . 4.18
4 - 9.04
5 - 9.04
6 - 9.04
7 - 0
8 - 0
9 - 0
10 - 0 . 4.15
11 - 9.03 . 4.18
12 - 0
13 - 0 . 4.86
14- 9.04

Checking with the audio probe I:
- Don't get signal in Pin 3 IC4, Pin 7 IC4 neither Pin 7 IC6.
- Get very low signal in Pin 6 IC2 and R13.
- Get very low NOISE pin 1 IC1

Please folks help me out with this madness !

Ignacio

Everything rechecked.

Had a wrong resistor in r54. Just replaced and still
Can't delay the fx.

No signal in ic4 with audio probe. Very low Signal in pins 3 and 4 of Ic5.

No signal in pin 1 Ic1. Signal in pin 2 Ic1 (as loud as heared at input fx pad)

Very low signal at r13.

No signal in pin6 IC2 and pin7 Ic6.

What the hell is going on? I'm pretty sure that everything is well soldered in the right place. 

Waiting for your answer ! Thanks

Hi Bean !

Apologise me for my mistake. I'm not using 3005... They are MN3205, supposed to be originals ( bought them from a trusty dealer)

R11 and 12 both are 47k. No signal in pin 7 IC4.

Only signal in pin 3 and 4 IC 5 when the level is fully clockwise and the bend pot is fully counterclockwise. The Blend pot works as a strange kind of volume pot. When it is fully clockwise the effect does not sound, when it is fully counterclockwise the effect is more gainy !

Neither work the modulation led.

And Yes the signal of my audio probe does enter by the IN pad into the PCB. Cheking the fx with the output to the Amp and the input signal as my audio probe despite of the guitar.

Going to recheck EVERYTHING.

Thanks

Ignacio

Hi folks,

Just finished my Dirtbag powered at 9v. I payed attention to every solder I made (because of the high level required to do this kind of project) but I haven't been able to make it work properly.

The guitar sounds with the effect engaged although can't get the delay sound. Pin 3 of IC4 and IC5 does not response to the audio probe signal.

Think it looks quite good:



Hope you can help me to run it !

Voltages:

IC 1
1 - 5.20
2 - 5.20
3 - 5.10
4 - 0
5 - 4.73
6 - 5.20
7 - 5.20
8 - 9

IC 2
1 - 6.51
2 - 6.72
3 - 6.72
4 - 0
5 - 7.64
6 - 7.54
7 - 8.3
8 - 6.88
9 - 6.88
10 - 8.35
11 - 7.79
12 - 6.45
13 - 9
14 - 7.15
15 - 7.15
16 - 6.45

IC 3
1 - 5.20
2 - 5.20
3 - 5.11
4 - 0
5 - 5.04
6 - 5.21
7 - 5.21
8 - 9

IC 4
1 - 0
2 - 9.04
3 - 4.25
4 - 4.36
5 - 8.11
6 - 9.04
7 - 7.49
8 - 7.75

IC 5
1 - 0
2 - 9.04
3 - 3.79
4 - 3.87
5 - 8.11
6 - 9.03
7 - 7.12
8 - 7.75

IC 6
1 - 6.10
2 - 6.06
3 - 5.94
4 - 0
5 - 5.49
6 - 5.66
7 - 6.12
8 - 9.04

IC 7
1 - 4.38 - 5.14 (Oscillating)
2 - 4.73
3 - 4.77
4 - 0
5 - 4.73
6 - 4.78
7 - 4.76
8 - 9.04

IC 8
1 - 5.20
2 - 5.20
3 - 5.05
4 - 0
5 - 7.59
6 - 7.63
7 - 8.35
8 - 9.04

IC 9
1 - 9.04
2 - 0
3 - 0
4 - 9.04
5 - 9.04
6 - 9.04
7 - 0
8 - 0
9 - 0
10 - 0
11 - 9.03
12 - 0
13 - 0
14- 9.04

Looking forward to hearing from all of you Masters

Ignacio
14

That's true... Transistors above 600hFE to build MUFF fx... My G2 sounds amazing, athought it is a lil' dark (even after I did the brighty mods)

Can anyone answer this question ?

On the other hand, I think we ought to improve the switch noise it produces between vibe and tremolo.

Is it possible to include a pull down 1 M resistor? Where?

Thanks

Eooo ! Has anyone suffered from a POP Noise everytime you wanted to switch between Vibrato and Tremolo mode ?

This POP Noise is exactly the same as you ear when you turn on your Rangemaster without a Pull-down resistor...

What can I Do?

Thanks

Thanks Brian !

Can anyone answer this question ?

On the other hand, I think we ought to improve the switch noise it produces between vibe and tremolo.

Is it possible to include a pull down 1 M resistor? Where?

Thanks

Hi there,

I'm about to build one of those tone machines. Today dealing with my electronic supplier he asked me about the BC549's hfe, because he has 3 "models":

- BC549a = Fairchild. TO-92, 50V/100mA, hFE: 110~220.
- BC549b = Fairchild. TO-92, 50V/100mA, hFE: 200~450
- BC549c = Fairchild. TO-92, 50V/100mA, hFE: 420~800.

Which ones should I order to obtain the best of this effect ?

Gracias 

Wow ! Solved !!!

It was a little piece of soldered jumper between q1's source and the ground...

Now it is working ! And how it works !!! Sweet vibrato machine 

Tomorrow I'll play with the trimpots a little bit, trying to get the best of this machine out.

On the other hand, I think we ought to improve the switch noise it produces between vibe and tremolo.

Is it possible to include a pull down 1 M resistor? Where?

Thanks Don Brian ! (in some Spanish villages, people used to call DON to wisemen )