AION Lumitron Need troubleshooting help

[cbdiy]

Hi All, I've got a new Lumitron build that I just finished, but it isn't quite working correctly. It is passing sound, and I am hearing filtered sounds. The volume is low and the envelope doesn't really seem to be triggering. I was wondering if anyone knows what the correct pin voltages should be for the ICs. I'm not sure how this pedal is supposed to work or what it is supposed to sound like, so it is a little difficult for me to pin down the source of the issue.

[PRR]

Welcome!

Where did you get the plans or kit? There are variations. One common one uses a LT1054 or 7660 to make negative 9 volts. Relative to ground, do you actually have +9V some places and NEGative 9 volts other places? If so, you expect most other voltages to be very near Zero (say, +/- 0.1V).

Can you disconnect the opto-devices' LEDs? Some way to connect them to 9V through about 1k ohms, so they light-up internally? If they don't (bad optos, bad connection, etc) then the path is a severe high-cut filter, which will be lame and muffled. As a cross-check, tack 10k across R9 R10 to "fake" a wide-open opto- does that sound loud and bright?
https://aionfx.com/app/files/docs/lumitron_documentation.pdf
http://www.geofex.com/PCB_layouts/Layouts/neutronpub.pdf

[cbdiy]

It is the AIONfx version. I used a 1044 as it was what I had on hand, and I am seeing + and - ~9v. I am using 4558s that I got off of Amazon, and considering the provenance of some of those, I worry that I am not getting what I should. This is why I was wondering if anyone had a list of what voltages I should be seeing across the pins of those.

I will bridge the Optos as you indicated to see if they are the problem.

Update: I dropped 10K across R9 & R10 and it didn't have a major impact, so I think the problem lies elsewhere.

[cbdiy]

I should also mention, the other substitution I made was to use a MLCC 2.2uf cap for C11 instead of a film cap, but other than that, it should be pretty straight forward according to the AION plans.

[cbdiy]

I started tracing everything out and it was all dying at the output resistor, which was 560k instead of 560R. now I have an interesting fuzz pedal, so I am going to have to go and recheck my values, since I can't be trusted obviously.

[PRR]

560k instead of 560R

I do that a lot too. I've even bought resistor packs at Radio Shack, which was usually good this way, that were 100X off from the label. Part of becoming more expert is learning your favorite mistakes and checking for them often.

[cbdiy]

Found the problem. I traced out the cvircuit and found everything was dying at pin 7 on IC1, so I swapped out the 4558 (Socketed) and everything started working like a champ. I had a feeling that was going to be the issue. Just wish I had gone with my gut and started there.

[ElectricDruid]

Just wish I had gone with my gut and started there.

Generally not a good plan. A logical debugging approach tends to produce better resuls the majority of the time, as it did for you in this case. Start at the beginning, work through, get to the answer. *Sometimes* you can hit lucky on a hunch, but it's too rare to make it a worthwhile approach.

You could be really quite stupid, and I assure you, your brain is still far cleverer than your gut. So go with the brain every time.