Fender Blender issue

[salin4]

I have made a Fender Blender but I think some things doesn't work the right way:

It seems to work the way it should except :

- the volume pot : When it's at 0, I still have sound like a clean tone. When I turn it it begin to sound louder but also with more gain.
- The Led related to the tone switch doesn't work ( the blue wire on the photo is here to make it work).
- The tone switch acts strangely: When I push it I have a bit more volume and a sound that reminds me a ring modulator ( but really less pronunced).

I have the feeling the problem is related to the tone switch/part, but I'm not really into electronics so I don't know how to solve it.
If someone has a clue... Thanks !

 

[benny_profane]

Your TONE and BLEND pot values are swapped. Go back over the board and ensure there are no more errors.

EDIT: Pots are correct. The advice to verify part values remains.

 

[salin4]

According to the value on the board, I don't think they are swapped.

 

[benny_profane]

My mistake. I referenced the build document and mirrored it by accident. You're right.

 

[salin4]

I have already checked everything...I noticed the two 820 ohms resistor had a bad value (680 ohms). I changed them but the problems are still here .Could some 2n5088 brand has reversed pin ? also there is a small scratch on the pcb ( cf photo) could it be the problem ?

 

[benny_profane]

That scratch appears to be over a plane fill and not shorting anything, so it should be fine. The jumper is concerning. Have you tried reflowing the joints? Those spots should have continuity and I don’t see damage to the board that would indicate a destroyed trace.

 

[salin4]

I have already tried reflowing the led's joints and also all of the tone switch joints.

 

[ClippyTheDiode]

Is it possible those glass diodes are in backwards? Specifically D1 and D2. It won't matter if you have D3 and D4 backwards, as long as they both are. Can you check with a DMM?

 

[salin4]

I just tested it, here's the result. It seems to be ok ? They are about 0,35v each.

 

[salin4]

Ok, so I know why I have clean sound when vol at 0.
When the blend is at min settings, the bypassed tone is active.
When It's at max settings it's inactive.
In this situation I get no sound when the vol is completely down which seems to be ok.
I don't know if it's how the pedal should react but it makes sence.
I put a mp3 file to hear how the pedal is reacting.
I'm playing a strat with single coils in a hx stomp with a clean amp
tone is at 12:00, blend at max (no clean tone), vol at 9:00
from the start to 0:25 : sustain at min
from 0:25 to 0:46 : sustain at max
from 0:50 to the end : tone switch engaged , sustain at 12:00

Fender Blender essai.mp3

drive.google.com

 

[salin4]

The Led related to the tone switch still doesn't work and I still find the sound is a bit weird when the tone switch is active. If someone has a clue ...

 

[Giorfida]

The Led related to the tone switch still doesn't work and I still find the sound is a bit weird when the tone switch is active. If someone has a clue ...

Not to dredge up an old thread, but I had the same problem and traced the problem to no continuity between the cathode pad of the LED and the 4th pad from the left on the board. I jumpered between the pads and it works fine for me