FV-1 Dev Board - Not getting audio from the FV-1 Chip

rjkuyvenhoven

New member
Tested my completed FV-1 Dev Board for the first time and I'm not getting any effect on the audio. The dry sound is passing thru fine. Mix knob turned full left I get full dry signal, when turned full right I get nothing.

I've tried it with the Spatialist and Module8 eeproms, no luck with either.

Using an audio probe I get audio on pins 1 & 2 of the FV-1 but nothing on Pin 28

I'm getting 3.3v on pins 6, 8, 23 of the FV-1 and 3.3v on pin 8 of the eeprom.

What would be a good next step to test?

Thanks.
 

phi1

Well-known member
You could try grounding fv-1 pin13. This will access the stock programs that are stored locally on the fv-1 chip. Look up the fv-1 datasheet for more info about these programs.

the easiest way would be to hook a wire onto the leg of R5 that connects to pin13 (make sure you get the correct leg). Let us know what you find.
 

rjkuyvenhoven

New member
Thanks.

With pin 13 connected ground, I'm getting audio from the FV-1 and audio goes thru the pedal as expected.

So that suggests there is an issue with reading the eeprom.

I confirmed continuity between FV-1 pin 14 and eeprom socket pin 6 and between FV-1 pin 15 and eeprom socket pin 5

eeprom pins 1,2,3,4,7 are grounded and as mentioned before 3.3v on pin 8

I have used the Spatialist eeprom in my Arachnid before and it worked fine. Nevertheless, I put it back in the Arachnid to confirm it still works fine and it does.
 

phi1

Well-known member
Huh that’s weird you checked it like how I would have done.

one other thought, maybe a long shot since you’re check seems to have been pretty thorough, you said you verified continuity to the correct pins, but you also need to verify there’s no short. For example you checked that eeprom pin6 connects to fv-1 14, but did you check that it doesn’t accidentally short to ground or 3.3v? Same with pin5. I know it’s a long shot, but it seems you’ve narrowed down the problem to the eeprom connection to the fv-1.
 

rjkuyvenhoven

New member
Did not think to check that. No shorts to ground or 3.3v or between pins 5 & 6. Strange.

Could the CH341 chip be interfering? I wouldn't think so as it's not doing anything. I did use 22p caps for C9 and C13 as I didn't have any 20p on hand.
 

rjkuyvenhoven

New member
Not really sure what is going on here so I took a couple shots in the dark (definitely not my preferred approach to troubleshooting). I swapped out the crystal on the unlikely event a timing issue was preventing the FV-1 from reading the eeprom. No luck. So I swapped out the eeprom socket. No surprise that this didn't work either.

If I had way to monitor the I2C bus that might provide a clue.

Anyone have any ideas what might be happening here?
 

kidchemical

New member
Just finished building this pedal (*edit: spatialist reverb*) earlier tonight, and I'm having the exact same issue. I'm fairly new to pedal-building, so I have no idea how or where to even start troubleshooting this.
 

doublej

Member
Try what phi1 said above about grounding pin 13 to ground. This will use the FV stock programs. It takes the eeprom out of play
 
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