Aion Theseus Not Working

[sclinchy]

Seems that I may be doing something dumb here. This is the second Aion pedal I've built that isn't working. I originally had D1 in backwards, but i fixed that. Interestingly, although i got no sound when the pedal was engaged with the backwards diode, the LEDs worked properly. When I rplaced the diode, I still had no sound, but the LEDs no longer work. Bypass mode works OK. I'm guessing the problem is in the outboard wiring or the input/output board.  I've tried some audio tracing, but I don't get any audio even into pin 2 of the first IC. At my wits end.  Any help would be appreciated.

[idy]

Welcome to the forum.
D1 is polarity protection. If reversing it to correct orientation causes LEDs to go dark, it is possible there is a short to ground somewhere in the circuit. I wold check resistance to ground from the diode cathode. (Turn power off when measuring resistances!)

Signal tracing needs to be thorough.
Signal on input jack?
Signal on footswitch?
Signal on PCB in?
Signal on IC Pin 3? (non-inverting input)
Signal on pins 1 and 2?
etc.

But before that you need to check power: 9v on cathode of D1? 9v on IC pin 8? 0v on pin 4?
Then the biasing of opamp: All other pins near 4.5v, with pins 3 and 5 possibly a bit low due to your meter "loading" them.

[sclinchy]

Many thanks for the quick and detailed response. I'll try to do as well in return.

Here's what I found:
9 volts on cathode of D1 - No. I do measure 9v at 9v pad on board.

I think we know the answers to these, but:
9 volts on pin 8 - No
Pins 3 & 5 - No

I can do audio tracing, but I think we've established we've got a power problem?  I cant find any obvious shorts. No continuity between the 9 volts on the pcb and ground.

Any idea where to go next?

[idy]

Make an effort to understand the schematic. The power part, on top, is a bit confusing, but not too complicated.
We can call the small board with the footswitches the daughter board. Here is where the power starts.
You say you can find 9v on the daughter board on the red wire from the dc jack?
But no power on the Diode cathode (the stripe end)?
What about the other end of the diode?

There are only three things attached to that "node:" two 10k Rs that feed the LEDs, and the diode.

You would expect to see 9v at anode and slightly less at cathode.

You could have damaged the diode removing it. Most meter have diode test function. You could short it out and be fine, as long as you don't hook up a reverse polarity power supply.

[sclinchy]

Thanks again. I think shorting the D1 spot makes a lot of sense, since we don't seem to have power getting any further than that. I'll try that in the AM.

[duck_arse]

also welcome, but you haven't posted the build docs. why not?

the leds are powered from the power supply unprotected by D1, so it won't matter which way it is fitted, the leds will light if power is correct. if they did light, but now don't, it suggests no volts to the board at all. or a dead short after the diode. which would smoke the diode.

are those wires single core or stranded? you should test continuity of those wires, from where to where. there may be a hidden break. and, I look at your board and try as I might, I can't figure the colour bands of R8. it won't be the problem, but would you be so kind to advise what those bands are? it doesn't match with the other 3 examples of the same value.

also also, not wishing to sound rude, but yes/no answers are less helpful when we ask about voltages than are the actual numbers on the meter.

[mozz]

Just built one of these and your pictures look good as to jack wiring and component placement.  Pull that led and wire it up with 5k- 10k resistor, neg to banded end, just to make sure it works and you have the right polarity. 

[sclinchy]

Sorry about not posting the build docs, they are here https://aionfx.com/app/files/docs/theseus_documentation.pdf

I removed d! And replaced it with a jumper and we made progress, the LEDs now light up, but still no sound. I'm measuring 9 volts across that jumper, and 9 volts at R29 and R30, but 0 volts at all of the pins of IC1. It seems that the voltage is still getting lost somewhere, maybe shorting to ground?  The only place along there that I'm finding continuity to ground is on pin 4 of each chip, which is correct.

[idy]

So now you are progressing to the next "node," the cathode of D1.
It attaches to:
C23 ( a little help filtering the supply)
R27 (small value resistor forming a filter with C21, providing power (VA) to the biasing system (VB)
R28 (another small R that forms a filter with C22 and provides power to VC, the main 9v power to the circuit.)

You want to see 9v on one side of R27 and 28, and just a bit less on the other. You want to make sure C23 is not shorted out.

[sclinchy]

Thanks again!

I've got 9 volts on both sides of my D1 jumper.

9 volts on the anode side of R29 & R30, 1.8 volts on the cathode.

C23 is not shorted.

0 volts on either side of R27 & R28. One side of C23 goes to ground, but not the other, so that looks correct.

[mozz]

Your terminology is not quite correct. You don't measure "across" a jumper. You have your meter negative lead on ground. Measure the jumper. Measure at the top of C23. Measure both ends of R27, R28. if the voltage gets lost you have to find out why. How about R12?

[idy]

The readings on R29 and 30 confirm what you know already: the LEDs are working. They drop 1.8 volts when operating. 
Somehow this poser is not getting to R27 and 28. There must be no continuity between those two and the cathode of D1. Maybe removing that diode pulled out the plating in the hole? Maybe the PCB is scratched between the diode and the two Rs?

You can jumper from D1 to those two Rs. Are R27 and 28 connected to each other?

[sclinchy]

I didn't mean to say that I was measuring across the jumper, just that i measured 9 volts on each side.  Sorry if that was unclear, I'm trying to impart as much information as clearly as possible, to be slightly less of a pain.

0 volts at R12 (both sides)

I measured continuity from C23 to R27 (I checked both sides of each) and I'm not getting any connection there. I should be, according to the schematic, shouldn't I?

[sclinchy]

So I poked a little more. Ran a jumper from D1 to C23 then to R27. Now, on IC1 I've now got:

Pin 8 - 9 volts
Pin 1 - 4.5v
pin 2 - 4.5v
Pin 3 - 4.3v
Pin 4 0v
Pin 5 4.5v
Pin 6 - 4.5v
Pin 7 - 4.5v

Still no sound, but it looks like we've got power!

[idy]

Congratulations, that is progress.
Now time to signal trace. You need a sound source, like a looper pedal or something so you don't have to strum a guitar while poking around.
The signal trace is just an instrument cable with 1/4" jack (or whatever plugs into the amp you are using for testing) at one end, and the other end you attach an alligator clip to the ground and a film capacitor (really any value over maybe 10nf) to the signal conductor. The alligator goes to pedal ground. The loose lead of the cap you can attach to a nice probe ( and maybe fit the cap inside something) or just use it as is.

Bypass works, so signal gets from jack to switch. Follow the schematic. Listen for signal on:
Channel A "In" on PCB.
C1
IC1 pin 3, then 1 and 2
IC1 pin 6 and 7
etc.

[ElectricDruid]

Congratulations, that is progress.

+1 agree, that's definitely a step forwards. Carry on!

[sclinchy]

It's alive!  Working great, the only problem is that I don't know why.

I traced through channel A, getting signal everywhere I should, right up to the output jack.  Plugged a regular cable in and it was working.  Repeated the same procedure on the other side, and that's working too.  Maybe a questionable solder joint?

I'm going to leave it alone for now, but keep an eye on it.

Thanks to everyone for your time and patience, especially idy. I literally couldn't have done it without you.

[duck_arse]

any word on those R8 colour bands?

[sclinchy]

I'm too old to read them, but I checked with an ohmmeter, and it's correct.

[duck_arse]

how old is too old?