Author Topic: Building the Christine oscillating fuzz PCB  (Read 47707 times)

Taylor

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Re: Building the Christine oscillating fuzz PCB
« Reply #100 on: August 03, 2018, 09:19:28 PM »
Hum could be a couple things: a lot of times a hum has to do with bad grounding. Make sure the ground lug from your power jack, the sleeves of the 1/4" jacks, and the G pad on the PCB all connect to each other at a central point. Make sure that the enclosure itself is grounded (sometimes with powder coated boxes, the powder coating on the inside keeps the 1/4" jacks from grounding the enclosure). Also, any high gain distortion will amplify hum if it's coming from your guitar (e.g. single coils).

Now, feedback, yes that's normal. This is a crazy feedbacking oscillating weirdo fuzz.

telebiker

Re: Building the Christine oscillating fuzz PCB
« Reply #101 on: May 09, 2019, 12:04:22 PM »
Trying to build this (my first build). The LED is working, but instead of sound there is only noise. Volume pot is reducing the noise level.

Going to disassemble this and debug where the problem is. I know that the design is not the best. Have to learn a lot of things.




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Taylor

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Re: Building the Christine oscillating fuzz PCB
« Reply #102 on: May 09, 2019, 11:35:21 PM »
I would start by making an audio probe and seeing if your guitar signal is getting to the In on the PCB, just to eliminate issues with the bypass board wiring. This circuit will oscillate and making all kinds of noise depending on the settings of the power and OSC pots, but especially if there is no input. Also make sure all your ground points from your jacks and both PCBs are connected together.

telebiker

Re: Building the Christine oscillating fuzz PCB
« Reply #103 on: May 16, 2019, 07:45:17 PM »
I have built an audioprobe. The thing is that some points have audio signal, some not. I have recorded a video where I'm testing all the contacts:



Unfortunately, I have not figured out where the problem could be. Would be grateful for any ideas.
« Last Edit: May 17, 2019, 10:05:48 AM by telebiker »
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patrick398

Re: Building the Christine oscillating fuzz PCB
« Reply #104 on: May 17, 2019, 05:31:26 AM »
I have built an audioprobe. The thing is that some points have audio signal, some not. I have recorded a video where I'm testing all the contacts:

https://www.youtube.com/watch?v=VoCZTxqnzMc

Unfortunately, I have not figured out where the problem could be. Would be grateful for any ideas.

There's not much sense in just probing randomly around the board, you need to get the schematic and follow where the signal enters and travels through the board. In the video it sounds like you've got no clean signal on the board input. Do you have a bypass switch wired up? I'd recommend wiring input and output jacks direct to the board for now, confirm the effect is working and then tackle the true bypass wiring.




telebiker

Re: Building the Christine oscillating fuzz PCB
« Reply #105 on: May 17, 2019, 09:42:32 AM »
There's not much sense in just probing randomly around the board, you need to get the schematic and follow where the signal enters and travels through the board. In the video it sounds like you've got no clean signal on the board input. Do you have a bypass switch wired up? I'd recommend wiring input and output jacks direct to the board for now, confirm the effect is working and then tackle the true bypass wiring.

I agree. I'm using an "Effect tester" PCB (https://www.delykpcb.com/product/effects-tester-mk-ii-pcb/) to debug the issue. As stated in the manual, I have connected 4 wires (9V, in, out, GND) and switched 3pdt which this Effect tester board has.

>  In the video it sounds like you've got no clean signal on the board input.

Does this mean that I should hear something while touching the board input with an audioprobe?

Also, am I right that "power starve" part from the schematics is not used in the pcb?
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Taylor

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Re: Building the Christine oscillating fuzz PCB
« Reply #106 on: May 17, 2019, 07:18:15 PM »
Yes, you should hear your clean signal at the board input.

The power starve part is included on the PCB. It's the top left pot on the board. Rather than working on the power input pin of the chip, it inserts a variable resistance between the chip's ground pin and actual ground.

telebiker

Re: Building the Christine oscillating fuzz PCB
« Reply #107 on: May 18, 2019, 09:20:40 AM »
If I hear distorted signal on the board input, what this could mean?
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telebiker

Re: Building the Christine oscillating fuzz PCB
« Reply #108 on: May 20, 2019, 07:04:57 PM »
It turned out that there was a mistake: I soldered one electrolitic capacitor wrong swapping polarity. I replaced it, soldered properly, and the circuit started to work as expected.

That would be interesting though to find out how it can be possible to investigate such issues with audioprobe? It gave me some weird results. What should I expect soldering the circuit in a wrong way?  :-X

Tried the effect on a bass, sounds pretty interesting. Will post some pictures later.
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Taylor

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Re: Building the Christine oscillating fuzz PCB
« Reply #109 on: May 21, 2019, 07:51:29 PM »
This particular circuit is probably more difficult to troubleshoot that way, because by design it's so chaotic and depends on the impedance of the source feeding it, etc. But in general, audio probing is useful for narrowing down the area where the issue lies. You can probe at the output of each active stage (opamp, transistor, or in this case inverter) to find where the signal isn't getting through.

telebiker

Re: Building the Christine oscillating fuzz PCB
« Reply #110 on: November 02, 2020, 08:37:11 PM »
Thanks everyone for helping with the build. My first pedal with a lot of errors during making.


soggybag

Re: Building the Christine oscillating fuzz PCB
« Reply #111 on: November 03, 2020, 12:31:16 PM »
What does that lower oscillator section do in this circuit?