Aion Lab Series Preamp -- bypass LED won't turn off?

[cajone5]

So I finally got a power supply for this and was able to test it out.  I haven't calibrated it yet but it appears to be functional.  Signal bypass works.  However, the LEDs won't turn off (channel LED's and bypass LED) no matter if I bypass the pedal or not.  I wired it based on the recommendation in the build doc for LED bypass off operation.  I also noticed what appears to be some bleed through when the pedal is bypassed (master volume adds noise when bypassed).  I haven't played around with it too much yet but I've checked continuity and the switch appears to be working OK although there is no drawing for how the bypass 3pdt PCB has the thing wired to the rest of the circuit.

I checked and there are no bad solder joints that I can see.  Anyone see anything obvious?  If I can't get it to work, I may ditch the PCB and wire the 3PDT myself although it'll require some head scratching to make sure I do it correctly with the channel footswitch.  My guess is the CH pads are used for the grounding of those LEDs so maybe the solution is to ditch the PCB and just wire the switch directly.  But before I do that, is there something obvious to try that I'm missing?

Build Doc: https://aionelectronics.com/wp-content/uploads/2016/04/aion-lab-series-preamp-documentation.pdf





Bypass PCB, other side


The bleed through has me worried about the switch and PCB still so odds are I'll replace it.  Just hoping I'm being dumb and the greater minds here will enlighten me.

Also, I did check and I'm getting +15.3V / -14.7V on the test pads so it appears my power supply and at least part of the circuit are OK.  I'll calibrate and debug (if necessary) after I get this issue dealt with.  I need to first track down an 1/8" to 1/4" tip converter so I can run a signal generator through it.  It sounds pretty good already though.

[darrenw6000]

In my experience leds have only stayed on if the negative pin is touching ground constantly. I don't know this particular project myself but I'm sure you will figure it out, components all look neat, good job so far!

[cajone5]

Well, like these things do, it stuck in the back of my head yesterday and last night so this morning when I woke up I had a possible fix.  I figured the issue could be from either footswitch PCB and since the bypass one appeared to be functioning right I disconnected the wire across the CH pads that provides ground to the LEDs for bypass off LED mode (in the build doc) and wired that from the channel footswitch to ground and all the LEDs function as normal.  I'll have to check the bypass issue and calibrate later but it was indeed a simple fix.  Glad I didn't toss the footswitch and PCB and rewire from scratch 



I prefer this setup anyway.  I misunderstood "always on" wiring of the LED so thought I didn't want it, but I do want to see what channel it is on even in bypass mode so glad I made the change.

[BrianS]

I have the same problem with mine so thanks for figuring that out. 

[cajone5]

Cool. Sounds like the channel pcb is always grounding the CH pad and running the wire across puts that ground always on the bypass led. Easy fix if that's all it is. Just dont use the CH Pads or (like I did) only use it to connect to ground on the channel board.

[dannoceti]

I have the same problem with mine so thanks for figuring that out.

I have the same problem too. Was going to live with it until I found this post.


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[Timko]

Awesome.  I was also having the same issue and this is a quick fix.  Thanks!

[pierre67]

 I had exactly the same LEDs issue and after a few days scratching my head I figured out the same fix...glad to know I wasn't the only one