Aion Electronics Alphelion build problem

[Big mike 1100]

Hi all!

I just put together an Aion Alphelion pedal and unfortunately it's not working.  Heres the link to the documentation:

https://aionelectronics.com/project/aphelion-mxr-distortion-plus-dod-250/

There are several versions/options and I've built the '77 Grey 250 version.

The IC Voltages are reading as follows:

IC1
1-8.81
2-8.32
3-8.83
4-8.82
5-8.84
6- 8.3
7-8.86
8- 0

IC2
1- 8.3
2- 8.2
3-- 8.8
4- 8.8
5- 0
6 -8.8
7- 0
8- 8.8

With a quick use of the Audio probe, the sound is strong following: RPD-C1-Comp1/2/3-Cx1-Cx2-R1.  It's very quiet at R2 and Pin3 on IC1.

***Not sure if it matters, but I don't have it wired to a 3PDT switch yet.  Besides the IN/GND/OUT holes, there's a SW hole, which I just connected to the ground of the output jack, with the understanding that it's just the Neg lead for the LED.  I think that's right, but could be mistaken.

[Slowpoke101]

Hi Mike,

Check your ground connection back to the battery (or DC socket ). Your voltages are indicating that your multimeter's negative lead is connected to your 0V source (battery or DC socket ) but there is no connection between the 0V source and the board's ground connection. Wiring problem?

[Big mike 1100]

Thanks, Ian. I'll check it out.  Is it possible that I'm incorrectly grounding the effect by connecting the SW wire to the sleeve of the Input Jack?

[Big mike 1100]

Not sure if I'm getting closer or farther away 

After fiddling with the wire connections the LED is not turning on, but the IC voltages are now:

IC1
1-0
2-4.4
3 4.4
4-0
5-0
6-4.4
7-8.8
8-0


IC2
1-4.4
2-4.4
3-4.4
4-0
5-0
6-0
70
8-8.8

[Big mike 1100]

***Solved****

Must have been a grounding issue.  Thanks Ian!

I think I had the SW wire in the wrong place while testing the pedal and it was screwing up the grounding.  Pedal is now working!

[Slowpoke101]

That is great that you have found the problem and now have another pedal to enjoy 

I don't see how having the SW connection going to the wrong place would upset the effect's grounding system, but you never know.
Most likely a poor solder connection was the problem or (and this is more likely) you used a powder-coated enclosure and it was isolating a connection that was supposed to be made via a conductive enclosure. It is best to have wiring between grounded points just in case of unexpected insulative properties. Then you may stumble across the dreaded "hum loop" - rare in pedals (apart from very high gain effects ) but common with amplifiers (as you would have found with your tube amp builds).

[duck_arse]

I think we should ask Aion to modify his circuit such that the unused half of the dual opamp does not have its input tied to ground, it might prevent some opamps doing strange out-of-spec behaviours ....... working, not working, working ....

[Big mike 1100]

Sorry for the delayed response.  I tested the pedal outside of the enclosure- I connected the sleeve of the input jack to the sleeve of the output jack temporarily with alligator clips/wire as additional ground.  When the SW pad was connected to the sleeve, the LED switch didn't work, but when I soldered it to the tip (temporarily mind you- I wanted to test the pedal without the 3PDT as it didn't work the first time with the switch connected).  I did resolder everything just in case, so there might have been a bad joint somewhere, but I didn't definitively see one.