Tone control in Little Green Scream Machine

[Olivier7960]

Hello
I just built the Little Green Scream Machine and I love it. I don’t know if you guys have the same issue but the Tone control has very little effect on the sound. Did I do something wrong ? Is there a value that I can change somewhere to have more impact on the sound ?
Thank you for your replies

 

[music6000]

Hello
I just built the Little Green Scream Machine and I love it. I don’t know if you guys have the same issue but the Tone control has very little effect on the sound. Did I do something wrong ? Is there a value that I can change somewhere to have more impact on the sound ?
Thank you for your replies

Did you use R7 - 220 ohm resistor, not 220K
220 ohm - Red, Red, Black, Black Brown.

 

[Olivier7960]

Yea it is a 220 ohms metal film resistor, 0,25 watts …. Red Red Black Black Brown

 

[JamieJ]

Can you post pictures of the component side and solder side of the board?

 

[music6000]

Yea it is a 220 ohms metal film resistor, 0,25 watts …. Red Red Black Black Brown

PICTURES!
I'm still thinking Resistors, 10K & 1K!

 

[Olivier7960]

Ok I will double check the resistors with the Color codes … in the meantime here is a picture of the build

 

[Olivier7960]

Mmm I double checked all the values and they are ok

 

[Olivier7960]

I will unscrew everything and post a picture of the underside in a moment

 

[music6000]

I will unscrew everything and post a picture of the underside in a moment

Did you use a Dust Cap on the Tone pot.
It needs to be properly insulated or it will short on the Solder tits!

 

[Olivier7960]

I am still waiting for the dust caps … in the meantime I put a piece of cardboard between the pot and the pcb

 

[music6000]

I am still waiting for the dust caps … in the meantime I put a piece of cardboard between the pot and the pcb

Has this solved your issue coz the rest of the Build looks very neat!
I have to ask, Did you use a W20K or B20K?

 

[Olivier7960]

Unfortunately no ! The piece of cardboard was already there when I first noticed the problem … I don’t know what to do … it’s like the pot has no effect at all … could it be faulty ? If it were I guess the circuit wouldn’t be working … but I have a good sound with little noise … I can play with drive and volume but the tone …. Nothing

 

[music6000]

Unfortunately no ! The piece of cardboard was already there when I first noticed the problem … I don’t know what to do … it’s like the pot has no effect at all … could it be faulty ? If it were I guess the circuit wouldn’t be working … but I have a good sound with little noise … I can play with drive and volume but the tone …. Nothing

Can you test for Continuity on matching circles .
You can also set DMM for resistance & Test if it vary's between Leg 2 & 3, Leg 2 & 1:

 

[Olivier7960]

By the way thank you for your help….
Resistance varies between the legs ….
There is good continuity between the points you circled …..

 

[music6000]

By the way thank you for your help….
Resistance varies between the legs ….
There is good continuity between the points you circled …..

Can you test for Continuity from opposite blue 220nF pad to top of 220r resistor?
You can see the trace in the PCB above!
Did you use a B20K for Tone pot?
Did you measure 220nF Cap prior to install?

 

[Olivier7960]

Yes there is continuity on the pcb trace you mentioned. I just measured the 220 nf cap and it reads 216 nf…. I used a b20k pot for the tone and the measurements I made confirm this

 

[Dan0h]

I just finished this build and used the specified “w20k” pot and it has very noticeable tone shaping as you twist through. I find it hard to imagine a B20k would not work but maybe that’s why they suggest using the W20k. Post a pic of the bottom of your board. My guess is you have some cold joints.

 

[music6000]

Yes there is continuity on the pcb trace you mentioned. I just measured the 220 nf cap and it reads 216 nf…. I used a b20k pot for the tone and the measurements I made confirm this

In simple terms in this circuit:
a B20K will only work in the first 1/3 of the pot rotation then basically nothing thereafter, you should hear something.
a W20 has an even sweep over the rotation of the pot that's why it is recommended!
a A20k bunches it all up in the last 1/2 of the rotation.

You may have a cold joint but the pedal is functioning??????

 

[Popnfreshbass]

Needs to be w20k from what Ive read. Otherwise you get the problem you’re having.

 

[Olivier7960]

I just took the multimeter to measure all the resistors … even if the Color codes are correct some don’t read the appropriate values … two 10k read 5k and two 510k read 400k …. Could it be the problem ?