Chauffeur (Daily Driver) Troubleshooting

[rgoodman]

Hello everyone, I built the daily driver clone and wow! I totally love this drive. It really suprised me by how good it sounded! I'm having an issue. Probably nothing to do with the circuit but my own mistake(s) somewhere. The pedal is making a high pitched squealing noise that is dynamic. I wonder if anyone can tell whats going on by the noise (maybe its a common noise for a particular issue). The noise occurs when powering on (engaging the footswitch) and fades away. The noise corresponds to the "gain" knob position it is not present or inaudible around 50% and below. It become apparent above 50%, increasing with the gain knob and occurs dynamically as I play. The harder I play, the noise is louder and also similarly fades away. Here is a link to my google drive folder housing 3 pictures and 2 videos (one video is audio only) demonstrating the issue. If you need anything else please let me know!

Shnobel Daily Driver Build Troubleshooting - Google Drive

drive.google.com

Thank you so much!

Bob

 

[Robert]

Separate the wires from the Input/Output jacks.

Twisting them together like that is a likely cause of oscillation, you want them as far apart as possible, preferably running down opposite sides of the enclosure.

The DC and LED wires are fine, just not the Input/Output signal wires.

 

[rgoodman]

Hey thank you so much for your help. I separated the wires but the issue is still occurring.

 

[rgoodman]

I've just updated the pictures in my google drive for more clarity. I took the LED off because when I touched the LED wires (the insulated part), the noise floor was reduced. Removing the LED did not impact the noise that you call oscillation. Also, when I touch PIN 8 of the 7660SCPAZ with my bare fingers, the oscillaiton goes a little crazy (much more than when I touch other components) and similarly fades away. I wonder if i could have added too much solder to the pins of the DIP8 sockets and there is a bridge. I also wonder if I should clean/scrub the board with IPA as there is a good bit of flux since towards the end of my build I ran out of thin solder wire and used a much thicker solder wire, more carefully but could have been much more careful. I wonder if there are bridges under any of the sockets but taking the sockets off seems difficult?

 

[rgoodman]

Just cleaned off all of the remaining flux from the board very well with IPA and the problem is still occuring. I've also inspected every solder joint to make sure no leads are touching, except for under the IC sockets.

 

[Funnel]

I’m not familiar with the “dynamic” squealing your experiencing. Though the video clip does remind me of the oscillation some fuzz pedals try to achieve. Anyways, have you checked component values and orientation? That messed me up on this build. Also, if you have an extra 7660 or one that you know works in another build try swapping it.

 

[swyse]

I've had something like this happen when I had a backward electrolytic cap in the signal path, I would check the orientation of the electrolytics. The schematic isn't on the build doc yet so I'm not sure which ones if any are in the signal path, but you might be able to trace it out.

 

[rgoodman]

Just checked all of the resistor and values, all orientations of caps and diodes is correct as well. I don't have an extra 7660 to test at the moment.

 

[rgoodman]

Just purchased another 7660 to see if that is the issue. Here is the version I'm using: https://www.mouser.com/ProductDetail/968-ICL7660SCPAZ

 

[swyse]

The way the sound was charging in mine was due to an electrolytic in the signal path so I still suspect something related to that. I looked at the pcb in the build doc and it does look like yours do all match that orientation. I would think maybe it's after the gain control because the gain control affects how its charging. The whine from the wrong 7660 is a fixed frequency all the time in my experience so I don't expect that to resolve it but who knows. @Robert could I borrow the schematic for this if you have a draft available?

 

[rgoodman]

Hey y'all, I may have discovered the issue or at least something that may lead us to the solution. When I touched the right leg (looking at the flat face of the transistor) of (Q3 2N4403 BJT transistor, PNP TO-92 from build documentation) with steel tweezers, the signal still sounds good and the noise goes away! I have added additional close up photos to my google drive folder found in post 1 of this thread. I wonder what could be going on here? Thanks a lot!

Also, here is the link to the exact transistor I am using: https://www.mouser.com/ProductDetail/512-2N4403BU

 

[rgoodman]

If I bridge the ground next to it in the far corner and the right leg (or left leg) of the transistor with the steel tweezers, the noise goes away and all is perfect! I wonder why this is happening. Should I just wire the ground to it or replace the transistor or something else?

Thank you
Bob

 

[rgoodman]

So I have an original daily driver that I bought since I lost hope in fixing this clone so I was able to compare them. I wonder if grounding this transistor (I did solder a leg to ground) removes it from the circuit? I don't have enough knowledge to know that, but the real daily driver sounds a little smoother with cleaner distortion (with a bit less "fluff" after a string is muted and less sharp trebly edges) and the original has some more midrange. I wonder if replacing the transistor is the way to go?

Maybe I damaged it by applying the soldering iron for too long and allowed solder to travel up the leg and damage the transisor? As you can see I need some improvement on my soldering skills (less solder, less heat etc.).

 

[Funnel]

Have you tried measuring the voltages of the transistor on the original vs. The clone? For that matter you could measure all transistors and ic’s to see the difference.
Also I would be curious to hear the difference between the two!

 

[Robert]

You don't want to ground Q3, it's acting as a voltage regulator.

Measure the voltages on each pin of the transistor and see what you have.

 

[rgoodman]

Okay, interesting stuff. This is all new to me so I youtubed how to do the reading. Also, I'm not sure how to communicate the measurements. Q1,2, 3 correspond to the pedalpcb build docs. E = emitter, C = collector. Here's what I've found:

Q1:
E = .649 V
C = .633 V

Q2:
E= 0 V
C = .593 V

Q3:
E = .643 V
C = .630 V

https://docs.pedalpcb.com/project/Chauffeur-PedalPCB.pdf

 

[Funnel]

I'm not sure if this will help, but here's what my transistors read. However, you can also compare your values to the original Daily Driver to see how they compare to yours. If all the values and orientation are correct I would try reflowing all of the solder points and start with the ones around the power section

Q1
C=9.02
B=5.65
E=5.63

Q2
C = 8.13
B = 8.06
E = 7.36

Q3
C= -3.60
B= -3.47
E= -2.78

 

[Robert]

I'm not sure if this will help, but here's what my transistors read.

Are you sure you have 1N5242B (or an equivalent 12V zener) installed at D6? You should have much closer to 9V on the base and emitter of Q1.

 

[Funnel]

Hmm… I have a 1n4742a but from what I understand it’s a 12v equivalent

 

[Robert]

Yep, it is, it should work fine.

This is a quirky circuit (including the original), there is too much current load on a single charge pump IC so the voltage sags like crazy.

Technically you should have around 16 - 18V VCC and around -5V negative VCC coming from the charge pump... VCC should not be dropping to 12V like it does in the original.