SOLVED Madbean AquaBaby - Modulation isn't modulationing

[coltonius]

Hey, all.

Analog modulation / delays are my Achilles heel, so I need some help here.

The Problem:

- The modulation does not work when I toggle it on.. sort of. The first repeat will be modulated if the delay is on when I flip the toggle. It does this in either direction (on or off). After that, nada.​

The Facts:

- Delay works perfectly. No problems with the main PCB.​

- The only voltage measurements provided in the AB Mod BOM are for the IC, which measures perfectly: 9v at pin 8, 0v at pin 4.​

- The internal red LED flashes appropriately. So does the external LED, which is a waterclear orange cleverly disguised on the right side under the knobs.​

- Rate works perfectly, varying LED flash speed.​

​

- The photocell is a leftover 9203 from a pile I bought at Small Bear and used on an ElectroVibe build (which was a success).​

- The photocell resistance does seem to be changing with the red LED and with movement from the Depth pot.​

- I used to have the LED and photo cell shrink wrapped to protect from light, but I removed it when troubleshooting.​

So what gives? It seems like the modulation board is working since there's a single chorused repeat when toggling in either direction.

The BOM: Madbean AquaBaby ModBoard

- I used Wiring1 on page 4 to connect to the main PCB. (Note that the way he's drawn the pots offboard does not match the schematic; Rate should have 2 wires because Lugs 2 and 3 are connected, not so on Depth.)​

The Photos:

 

[coltonius]

Following up to myself: I saw @MichaelW ’s build report on this very project and noticed he did follow the wiring suggestion for the Depth pot. It seems I was wrong to doubt Bean..

I’m off to fix the wiring and see if that does the trick. Back in a flash!

(And if anybody wants to explain how this makes a difference between no modulation and yes modulation, I’m all ears..)

 

[coltonius]

Back from hacking up the pedal, and it's working about as well as can be expected. I feel like the modulation is pretty subtle, which may be a function of the missing heat shrink, this particular LDR, or just the short delay time in general.

The solution was to wire the Depth pot according to the diagram on the build doc (bridge lugs 1 and 2 on the PCB), even though the schematic suggests otherwise.. D'oh! All's well that ends well!

 

[MichaelW]

Back from hacking up the pedal, and it's working about as well as can be expected. I feel like the modulation is pretty subtle, which may be a function of the missing heat shrink, this particular LDR, or just the short delay time in general.

The solution was to wire the Depth pot according to the diagram on the build doc (bridge lugs 1 and 2 on the PCB), even though the schematic suggests otherwise.. D'oh! All's well that ends well!

That enclosure looks great! If you saw my build report then you'll see my attempt at putting this all in the 125B was a massive fail hahaha.
But I highly recommend building the AquaBoy Deluxe for the full experience of this pedal. The second BBD and integrated modulation sounds a lot better to me than what feels like a hack with the Mod board added to the AquaBaby.