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Collosalus No flange

Started by eddth, October 28, 2018, 12:07:15 PM

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eddth

Hello guys, I've been trying to put together a collosalus flanger pedal. All components are in place but I've run in to trouble getting it to work as it's supposed to. Its the 2015 board using 9v power supply.

(1) Project Name -
(2) General description of the problem - When I use the pedal there is no flange effect, instead what can be heard is the bypass signal at a slightly lower volume.
(3) Steps that you have taken to try to resolve the issue - Checked all voltages on the ICs(see list below), adjusted knobs and trimming, checked for shorts, bad solder etc..
(4) List any substitutions you used for parts/values - I didn't have a 500K trimmer for the clock, therefore I used a 500ka pot instead.

IC voltages are what could be expected except for the ones listed below. The first number is from the build document, second I got from my project. The ones that I thought were off are marked red.

IC7
Pin1 21.8 17.1
Pin2 0 0
Pin3 14,82 15,25 The voltage here is a little higher then build doc. But 0,5v higher shouldn't matter right?

IC8
Pin1 1,42 2,6
Pin2 6,33 5
Pin3 0 0
Pin4 7mv 6mv
Pin5 100mv 0mv I looked at the schematic and it seems like Pin5 goes to ground. 0v should be OK then right?
Pin6 2,34 2,57
Pin7 1,46 1,52
Pin8 12 9,26

IC9 After trimming this one turned out OK.
Pin1 14,81 15,25
Pin2 7,37 7,5
Pin3 6,12 6,4
Pin4 1,54 1,78
Pin5 0 0
Pin6 7,37 7,56
Pin7 4,7-5,67 4,8-5,4
Pin8 4,7-5,67 4,8-5,4

I have an analog oscilloscope I could use for troubleshooting but I dont really know where to look. Any suggestions on how to proceed would be much appreciated.

Pictures are coming in a separate post.,

eddth


m-Kresol

First off, welcome to the forum.
secondly, thanks for following the tech help rules perfectly. We do see correct help requests way to infrequently.

your voltages on IC7 are fine. Brian used 12V input voltage, so the voltage doubler (IC8) will give higher voltages, which are regulated to 15V via IC7. you are getting 15V at it's output, so that's good and also IC8 is working as advertised.

I have not spotted any solder bridges or the likes, and your polarized components are oriented correctly.

You can go over all your component values again to check, but if your voltages are correct, then I doubt that there's something wrong there. I won't hurt though.
Having never built the Collosalus, did you hear flanging at all during biasing and trim pot setting? Where did you source your MN3007?
I build pedals to hide my lousy playing.

My projects are labeled Quantum Effects. My shared OSH park projects: https://oshpark.com/profiles/m-Kresol
My build docs and tutorials

eddth

I didn't hear any flange effect during biasing. The mn3007 is from musikding.de. They seem reliable..  I don't have another MN3007 to test with unfortunately.

stringsthings

It appears as if it's time for an audio probe.
All You Need Is Love

Bio77

I'm a rookie myself but I have a few thoughts: 1. D3 is omitted.  2. What value do you have at C16?  That cap looks big.

Also, I think the pot for the clock trimmer will be fine for testing, but you won't want to keep it that way.  The best way to set these up is to set your clock with a frequency meter and then bias the BBD. You can use your scope to bias the BBD.  Here's a post where I learned how to do this on the Current Lover, the procedure is similar but your frequency will be 30-35kHz at the minimum: http://www.madbeanpedals.com/forum/index.php?topic=27581.msg267486#msg267486

You can use your scope to trace the signal all the way through the circuit the same as an audio probe to diagnose any bad parts or cold solder joints.  Just put a sine wave into the input jack and follow the signal through each step of the schematic.  For the sine wave, I use aa app called Function Generator on my phone and a headphone jack I wired to a 1/4 inch plug. 

eddth

Quote from: Bio77 on October 28, 2018, 11:23:33 PM
I'm a rookie myself but I have a few thoughts: 1. D3 is omitted.  2. What value do you have at C16?  That cap looks big.

Also, I think the pot for the clock trimmer will be fine for testing, but you won't want to keep it that way.  The best way to set these up is to set your clock with a frequency meter and then bias the BBD. You can use your scope to bias the BBD.  Here's a post where I learned how to do this on the Current Lover, the procedure is similar but your frequency will be 30-35kHz at the minimum: http://www.madbeanpedals.com/forum/index.php?topic=27581.msg267486#msg267486

You can use your scope to trace the signal all the way through the circuit the same as an audio probe to diagnose any bad parts or cold solder joints.  Just put a sine wave into the input jack and follow the signal through each step of the schematic.  For the sine wave, I use aa app called Function Generator on my phone and a headphone jack I wired to a 1/4 inch plug. 

You nailed it spotting that huge cap. I was supposed to be 100pf and instead it was 2,2uf. No idea how I managed to miss that. Thanks for the help everyone! I will look to bias it like you suggested some other day.