Aion Elysium thumping noise

[Kris100]

Hi All,

I just finished building the Aion Elysium (Ibanez EM5 Echomachine clone) and have an issue with the pedal having some thumping noise which starts to self oscillate with feedback turned up. This happens even with guitar not plugged in which means the noise gets generated someplace in the circuit. I checked it on a power adapter and through battery power with same result. I went through all basic checks on part values, alignment, cap & diode polarity etc and don't see anything wrong. Only thing that comes to mind is the L7805 regulator - is it possible this creates noise which gets amplified through the delay chip? Noise rate follows pot settings - level makes it louder, delay controls the speed of the thumping, feedback makes it oscillate.

Pedal itself works when I plug in the guitar - all pots work correctly, I can adjust the internal trim pots etc however with the current issue present it's unplayable. I used standard 78L05 regulator, looking through BOM it refers to Mouser for LM78L05 (926-LM78L05ACZ/LFT7 mouser code) - is that something worth getting and replacing?

Aion BOM for this build >> https://docs.google.com/spreadsheets/d/18f6kvSrgOrAysngqES_IV0DSfYO0Tc3MUngthaZUwHU/edit?usp=sharing

Aion build docs with schematic diagram >> https://aionfx.com/app/files/docs/elysium_documentation.pdf

Thanks in advance for your help!

 

[Brett]

I'm not familiar with this particular circuit, but here are some ideas:

• You should be fine with the 78L05 as long as your pinouts match the specified part number: [1] VOUT [2] GND [3] VIN
• You didn't include any pics of your build, upload a few well lit pictures of the front and back of the board including wiring when you get a chance.
• Where did you source the delay chip?
• Did you follow Aion's calibration procedure in the build docs?

Lastly, if you're not already, you may want to familiarize yourself with an audio probe. You can DIY one if need be. It may prove useful for chasing down where this "thumping noise" is first generated in the circuit.

 

[Kris100]

I'm not familiar with this particular circuit, but here are some ideas:

• You should be fine with the 78L05 as long as your pinouts match the specified part number: [1] VOUT [2] GND [3] VIN
• You didn't include any pics of your build, upload a few well lit pictures of the front and back of the board including wiring when you get a chance.
• Where did you source the delay chip?
• Did you follow Aion's calibration procedure in the build docs?

Lastly, if you're not already, you may want to familiarize yourself with an audio probe. You can DIY one if need be. It may prove useful for chasing down where this "thumping noise" is first generated in the circuit.

Thank you for the suggestions. Following your points:

- Pinout for the Vreg is the same and I am getting 5V out of it. Just to make sure it's not causing any issues I replaced it but it did not make any change.
- Pics + a short video showing the issue attached
- I got the chip from banzaimusic.com - I consider them trustworthy, I bought multiple NOS chips from them in the past and all worked perfectly fine. Also worth to mention this one does work in creating repeats for the input when I plug in a guitar. It's just the pulsating / thumping noise that is in the background at all times in tempo with the delay time set
- I went through Aion's calibration instructions but trimpots have no effect on what I am experiencing - there are 3 trimpots, one for feedback trimming and 2 for min / max delay time. All seem to be working fine but no setting on these makes the noise go away

In terms of audio probing - I have some basic understanding of how it's applied, however on this issue I am not sure how I could troubleshoot with an audio probe where the issue is not caused when you have an active input signal. It's there at all times so I need to have a way to locate the component(s) which cause it - most likely something on the chip input side which constantly creates the noise. Do you mean I could try to bypass part of the circuit from the chip input stage to see if the noise goes away? If the issue was that I get no delay or sth like that I could bypass input, piece by piece up until chip input to see where I get the pedal to respond. Here I feel it's bit more tricky since it works overall - delay works, all pots work, trimpots work but I need to find the piece which must be broken or having incorrect value.

Next step is to go through resistor values to see if I haven't misplaced some by accident, putting wrong value in incorrect place.

 

[Kris100]

I'm not familiar with this particular circuit, but here are some ideas:

• You should be fine with the 78L05 as long as your pinouts match the specified part number: [1] VOUT [2] GND [3] VIN
• You didn't include any pics of your build, upload a few well lit pictures of the front and back of the board including wiring when you get a chance.
• Where did you source the delay chip?
• Did you follow Aion's calibration procedure in the build docs?

Lastly, if you're not already, you may want to familiarize yourself with an audio probe. You can DIY one if need be. It may prove useful for chasing down where this "thumping noise" is first generated in the circuit.

Adding a link for the yt video

 

[Brett]

Thank you for uploading all of the images and video!

Have you verified that all transistors are correct as well?

How careful were you when handling the CMOS inverter chip? Those are sensitive to static discharge.

 

[Kris100]

Thank you for uploading all of the images and video!

Have you verified that all transistors are correct as well?

How careful were you when handling the CMOS inverter chip? Those are sensitive to static discharge.

Yes, I verified all transistors (have not pulled them out of the board to test but right parts are in the right positions).

In terms of CMOS inverter - I was careful and just to test I replaced it with another one I have (bought a couple when I was ordering them from Mouser). I have the same exact issue on both so would need to be very unlucky to cause same issue on both when handling them... but who knows, anything is possible