Pythagoras V3 with no wet sound

[joelthornhill]

Hi,

Got my first FV-1 build for a nice isolation project with the hope to write/edit some of my own programs

However, I'm struggling to think of what to check next to get it working. Weirdly it was working for a brief period and then when it came to box it up it stopped working and I haven't been able to get it to work again.

What I've tried so far
- tested dry signal with mix knob - this works fine so definitely something to do with the wet signal path
- tested continuity between fv-1 pins, no accidental solder bridges between then
- tested continuity of fv-1 to related components, all seemed to make sense
- checked voltages, 3.3v where appropriate, I'm not sure what all the other pins should be but nothing seemed wrong
- tested pins 4, 7, 11, 12 go to ground
- grounded pin 13 (by grounding R5) to bypass the EEPROM but no change
- used an audio probe, signal at pin1 and 2 but nothing at pin 28 or 27

Some extra notes
- I reflowed some solder on all the pins a couple times, maybe I could have overheated the fv-1 or damaged the board
- I accidentally melted C9 as you can see, still looks like it would work though. This capacitor always seemed weird to me too since its not +/- or cylinder
- I don't have anything to test the crystal is working okay
- The momentary switch is to attach to one of the pots to max it out for infinite reverb etc but I disconnected to test

Any help would be appreciated!

 

[phi1]

That white cap should be 1u, not 1n. Not sure if that would cause your problem though.

Sounds like you’ve done a lot of the right steps, maybe it’s the fv-1 chip... one more thing you should try is to inject signal into where it comes off of pin28 to make sure it reaches the end, and there’s not an issue in between the fv-1 and where the signal is mixed.

Maybe best to remove c8 to protect the fv-1 from any unexpected voltages, and inject signal using an audio probe at R17.

 

[joelthornhill]

Hmm good spot, this is a kit from Musikding so I have no other caps right now, I’m going to recheck all caps to make sure they match and I didn’t put something in then wrong place

Cool thanks I’ll give that a go and if I still can’t get it to work I guess I’ll have to order another chip and have fun desoldering

 

[phi1]

That cap right below the the switch should have been the 1n. That would definitely roll off highs going into the fv-1, but I’d think it would still pass signal... any yeah double check l everything else too.