Author Topic: My first build, a Mudbunny 2020, but getting whine and noise  (Read 382 times)

shampeon

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My first build, a Mudbunny 2020, but getting whine and noise
« on: April 16, 2022, 04:43:53 PM »
Hey everyone. I decided to dip my toes into pedal building, and decided to start with a Mudbunny 2020.

The actual build went pretty quickly and smoothy, until I ran out of my favorite solder, and found some Bernzomatic rosin core in my supplies that I ended up not liking at all. But I finished everything, and after reflowing some joints I got the board LED to light up.

I plugged it into my amp, and there is a lot of noise with it off, which should have been bypassed. The noise increases with the Volume, and alter with the Sustain and Tone pots. When I turn it on, it makes a constant loud whine that modulates with the Volume, Sustain, and Tone pots.

Here's a video of the noise and whine.


I took a look at all the solder joints and reflowed some that seemed dull, and checked continuity, but no dice. I'm pretty much stuck, and have no idea how to fix this.

Here's the voltage measurements:

DC +: 8.75 V from the wall wart

All transistors are 2n5088.

Q1
C: 4.036
B: 0.635
E: 37.5 mV

Q2
C: 4.05
B: 0.634
E: 37.4 mV

Q3
C: 3.98
B: 0.63
E: 37.8 mV

Q4
C: 4.774
B: 1.44
E: 0.862

jimilee

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Re: My first build, a Mudbunny 2020, but getting whine and noise
« Reply #1 on: April 16, 2022, 06:17:12 PM »
I feel like your stomp board is upside down. The square should be pin one, so all of your wiring is reversed. Itís hard to see whatís going o without seeing the other side of the stomp board. It would just be a matter of rewiring the board if it is backwards.


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shampeon

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Re: My first build, a Mudbunny 2020, but getting whine and noise
« Reply #2 on: April 16, 2022, 07:14:26 PM »
It's a wiring board from Stompbox Parts: https://stompboxparts.com/pcbs/wiring-board-for-3pdt-footswitches/.

1. Input signal to FX PCB
2. Input signal from input jack
3. Ground
4. Output signal from FX PCB
5. LED
6. Output signal to output jack
7. Ground

The connection from the PCB is:
GND -> 3. Ground
L -> 5. LED
IN -> 1. Input signal to FX PCB
J1 -> 2. Input signal from input jack
OUT -> 4. Output signal from FX PCB
J2 -> 6. Output signal to output jack
« Last Edit: April 16, 2022, 07:52:45 PM by shampeon »

gordo

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Re: My first build, a Mudbunny 2020, but getting whine and noise
« Reply #3 on: April 16, 2022, 07:31:16 PM »
Iím gonna go with a stomp board problem too. If you can, just wire the in/out/9v/ground wires to the jacks and power, bypassing the switch altogether.
Gordy Power
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shampeon

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Re: My first build, a Mudbunny 2020, but getting whine and noise
« Reply #4 on: April 16, 2022, 08:00:22 PM »
Here's a front side view of the switch/wiring board.

shampeon

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Re: My first build, a Mudbunny 2020, but getting whine and noise
« Reply #5 on: April 16, 2022, 08:17:42 PM »
I labeled the wiring board with all the pin connections. I'm pretty sure this is correctly wired. When the switch is on, the top row is connected:
J1 -> IN (input jack connects to pcb input)
L -> GND (turns on LED)
OUT -> J2 (pcb output to output jack)

When it's off:
J1 -> J2 (full bypass of input jack to output jack)

jimilee

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Re: My first build, a Mudbunny 2020, but getting whine and noise
« Reply #6 on: April 17, 2022, 09:56:14 AM »
What weíre saying is, the square is pin one, you have it on pin seven.


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shampeon

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Re: My first build, a Mudbunny 2020, but getting whine and noise
« Reply #7 on: April 17, 2022, 10:04:45 AM »
I'm super confused. Nothing is connected to pin 7 on the switch board. See the front side pic above. https://www.madbeanpedals.com/forum/index.php?topic=33728.msg323983#msg323983

jimilee

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Re: My first build, a Mudbunny 2020, but getting whine and noise
« Reply #8 on: April 17, 2022, 05:07:51 PM »
Pin (Lug) 7 on the stomp switch is what Iím talking about, sorry for the confusion.  Pad 7 on the stomp board is a ground. Lug 7 is the effect out.


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shampeon

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Re: My first build, a Mudbunny 2020, but getting whine and noise
« Reply #9 on: April 17, 2022, 08:17:12 PM »
Thanks for all your help, I do appreciate it.

I rotated the switch 180 and resoldered it. I checked with a multimeter, and the switch seems to me to be working correctly.

ON
J1 -> IN
OUT -> J2
L -> GND

OFF
J1 -> J2
IN -> GND

But.... Didn't make a difference, as the whine and modulated theremin sound is still there. So back to square 1.

mjg

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Re: My first build, a Mudbunny 2020, but getting whine and noise
« Reply #10 on: April 18, 2022, 03:55:54 PM »
To rule out any issues with the switch, desolder or cut the wires, and just hot wire together the J1 to In, and J2 to Out.  See if it works like that?  But based on your measurements it seems like the switch is doing what it should. 

Next step might be to make an audio probe (itís easier than it sounds) and work your way through the circuit to see where it gets noisy. 

First thing Iíd check is whether youíve accidentally soldered the input or output jack wires backwards - tip to sleeve or something like that.  I know Iíve done that before!