Foxx Tone Machine noises

[JonesXavier]

Hello!
I've built the FTM a few times and I've always really liked it, but it always bothers me the way a noise gradually appears after stopping playing, this gradual noise was also reported on the Home Wrecker website (https://home-wrecker.com/ftm.html)
I've been discussing with some members here about this defect and I'm posting some assembly records here for help. I'm willing to make mods if needed and monitor progress.
I've built this circuit several times and there's always something like this.
As requested, follow:
-Photos of the assembly
-Default audio
-Videos of the voltages measured on the collectors and emitters of the 4 transistors while playing with the circuit.
-Layout used

FTM - Google Drive

drive.google.com

Thank you all and I hope we can improve this circuit together!
(English generated by the translator, I'm from Brazil)

 

[Ginsly]

Hmm that actually does sound familiar. Does it happen in Normal mode and Octave Up mode? I've always found the non-octave mode to be a bit noisy in FTMs, but the octave-up usually gates a lot of that out.

 

[temol]

First of all - make sure there's no shorts, solder bridges, etc..


First suspect.

 

[JonesXavier]

Hmm that actually does sound familiar. Does it happen in Normal mode and Octave Up mode? I've always found the non-octave mode to be a bit noisy in FTMs, but the octave-up usually gates a lot of that out.

Yes, I tested it here and in both modes the noise appears gradually after playing. In fact, in non-octave mode it is much noisier, but with the octave on it still occurs.

First of all - make sure there's no shorts, solder bridges, etc..

First suspect.

Ok, I got all the tracks with the multimeter continuity test.Here is a photo of this part of the board against the light, I believe the glow of the solder flux appeared in the previous image.

IMG_20240228_184213042.jpg

drive.google.com

Thank you!

 

[Chuck D. Bones]

Where did you get that board and have you verified that it is routed correctly?

 

[JonesXavier]

Where did you get that board and have you verified that it is routed correctly?

I designed this PCB myself, following the Fuzz Central scheme. I just checked again and didn't notice any errors.
It's worth remembering that I've already assembled this pedal other times with other layouts and was able to verify this oscillation.
I noticed in the Ayon FX schematic that it replaces the 10u capacitors with 1u, would this be a way to eliminate this defect?
Thank you very much for your attention!

 

[Chuck D. Bones]

How are you powering yours? Battery or external power supply?

I built the Aion Vulcan and it does not oscillate.

 

[JonesXavier]

How are you powering yours? Battery or external power supply?

I built the Aion Vulcan and it does not oscillate.

I'm using a power supply with transformer and regulator that I made, using this scheme.
Interesting that the Vulcan scheme did not oscilate, perhaps reducing the electrolytics could make a difference, I will test it!
The transistors used are 2n5088.
Thank you very much!

 

[Chuck D. Bones]

Try connecting a 100uF cap from +9V to gnd. The schematic you posted has no power supply bypass cap

 

[JonesXavier]

Try connecting a 100uF cap from +9V to gnd. The schematic you posted has no power supply bypass cap

I already added this capacitor to the layout when I drew it. The Power Supply also has the 100n one found in Vulcan.
On the Vulcan there is also a 12k resistor in series with 3 on the gain pot.
One more difference I noticed.

Layout ftm.PNG

drive.google.com

 

[Chuck D. Bones]

Can you provide the as-built schematic? Perhaps the oscillation is caused by the lack of a ground plane.

 

[JonesXavier]

Can you provide the as-built schematic? Perhaps the oscillation is caused by the lack of a ground plane.

So, I designed the board using DIYLC, this program does not need the schematic to generate the board.
I will add a PDF to the drive with PCB files with and without components for analysis.
Thanks

Foxx PDF layout e pcb.pdf

drive.google.com