SOLVED Aion Xenotron / Lovetone Flange no BBD modulation


Hey, hope I can ask you All for a bit of help and / or advice - Finished this build yesterday... and surprise surprise it doesn't work :) I've built 150+ pedals and never ended up with a build that doesnt work (including couple Aion Lovetone builds) so I really hope I can get this one working as well.

Pedal has 3 separate 3PDT's where 1 is for the effects loop, 1 for time modulation and 1 for space modulation. Time and space LEDs follow rate of modulation set by the pot. There are several internal LED / LDR combo - 2LED / LDRs for the Space on the main PCB, 1 LED / LDR for Time and additional LED / LDR for time on the BBD sub board.

3PDT LEDs light up, space and time ones pulse in tempo with the rate, SPDT switches seems to work, pedal passes signal through but there is no BBD LFO modulation. Space switch engaged works as a tremolo but Time doesn't seem to create any chorus / flange modulations. When I max out Manual control I can get some weird faint modulations with the internal BBD trimpot tweaked right but nothing that resembles typical chorus / flange vibes.

In terms of troubleshooting - I checked IC orientation, polarity of all components, triple and quadruple checked all wiring. I made sure I used a working MN3207 and MN3102 set from a chorus pedal I built a while ago. I also checked both PCBs for shorts or bridges, cleaned them with IPA and reflowed the few components connected to the LED3 that's connected to main 3PDT time f-switch. I tried to connect to Time Out jack and tweak the bias and all controls but I get nothing that sounds like a chorus / flanger.

Looking inside I noticed couple of things
- Space 3pdt engages the internal LED 1&2 which pulse along Rate control (the 2 LEDs which are inside a "fence" made of film caps),
- Time 3pdt turns the internal LED 3 on but this one doesnt pulse at all (bottom left corner of main PCB). Neither bias nor regen trimpots do any difference. I tried to follow the biasing instructions from build docs but having no LFO on any BDD trim setting not much I can do.
- The LED on the BBD sub board lights up and pulses with varying speed depending on Manual, Rate and Depth.

My guess is the LED3 on the main board should also pulse following rate but cannot see or measure anything obvious that could stop it from working. I am adding few pics of the build and schematics from Aion's build docs (pages 21-23).

For reference below a link to a build of another forum member that works perfectly, there's also few photos of internals and a short demo.



  • PXL_20231120_160350543.jpg
    387.8 KB · Views: 37
  • PXL_20231120_160419368.jpg
    378 KB · Views: 37
  • PXL_20231120_160434165.jpg
    462.9 KB · Views: 30
  • PXL_20231120_160516082.jpg
    421.5 KB · Views: 38
  • xenotron_documentation Noname flange.pdf
    1.1 MB · Views: 4
Last edited:
I needed to take a break from this one and built the Ring Stinger which was another intimidating Aion board that was waiting it's turn. Turned out perfect, no issues whatsover :) Freakish yet very musical pedal.

I plan to come back to the flanger once I get correct clear LED for BBD board - after some checking I am sure the ultrabright one I used is way out of spec for this place. The recommended one has brightness around 80mcd while the one I used is I think 10000+mcd... :) which surely affects my issues with Manual control and better bbd biasing. I just cant find anything locally like the transparent green LED Aion recommends so until I get the correct one this project fix is on hold. To be continued!
Short update - I swapped...
Check C1, C2 and C3. The values all look good, but I cannot verify C2 as the correct cap. Make sure there is no continuity with C1 and C3.

I would reflow C1, C2, C3, and R43 to see if you can get LED3 to work.

See if any of that works and let us know. It sounds like an LED3 issue, so we should be able to isolate the problem.
Thanks for the reply! Tried all of the above but still nothing. Trying to exclude potential issues I disconnected the CV jack and trig / gate jack - build docs mention these are not needed and no jumpers are needed also. I also reflowed all joints on the main / sub PCB connectors.
I am also currently building this and have actually been dreading the fire-up exactly for the reason of the difficulty level of troubleshooting.

I feel your pain, buddy.
good luck with yours, I tried to go slow and be cautious to avoid trying to fix this mess but I guess you never know when your time for "what went wrong" comes
I'd rather it be in a low-count fuzz circuit--I had enough issues with the twin face! I really don't want to face down this monster board. Always learning, but also always frustration.
This reminds me to look at the one I've got under my bench- I've got a very similar issue.

The trem works perfectly, but I can't seem to lower the delay time enough for flange sounds, though I am able to get some chorusing and vibrato
Does the "Time" LED pulsate? I am referencing the LED that we see when the footswitch is engaged?
Im not skilled enough in reading the schematic to tell what drives the voltage sweep that makes the LED pulse, perhaps it's something different entirely and this one should not pulse at all? I don't see the VD circuit being referenced for LED3 in the schematic and I might be bad in reading these things but all I see is a straight VC feed with a fixed 4k7 resistor on the other end going to ground. Not sure how that could change the voltage at all to be honest. I just assume that LED1-4 being coupled with LDR they should change light intensity to do something... :)
Disclaimer- I am also not very skilled in the electrical knowledge. However, I am happy to continue to help, but it might be the “blind leading the blind.” 🤣

Let me crack open my pedal and do some voltage readings. We can compare voltages and see if we can find where the issue resides.
Disclaimer- I am also not very skilled in the electrical knowledge. However, I am happy to continue to help, but it might be the “blind leading the blind.” 🤣

Let me crack open my pedal and do some voltage readings. We can compare voltages and see if we can find where the issue resides.
Ok thanks and I very much appreciate your willingness to help here :) We're all struggling to understand the magic juices that run pedals ;)
Comparing my pedal, LED 3 does not blink. If LED 4 is blinking, then that suggests that the 3201 IC functions. Can you measure the voltages on 3207 IC?

Here are my voltages for the 3207:
1: 0
2: 2.8-3.20
3: 3.18-3.3
4: 6.17-6.59
5: 6.59-7.05
6: 2.9-3.28
7: 4.08-4.23
8: 4.14-4.3