Author Topic: How Many Bad FV-1's In a Batch?  (Read 643 times)

vigilante397

Re: How Many Bad FV-1's In a Batch?
« Reply #20 on: April 10, 2020, 12:29:14 PM »
They're not that expensive, but I would love to not have to do that. https://www.newegg.com/p/0X6-04KT-0MVH2?item=9SIAM2VB8J3683

And actually I said I have that crystal working fine in two other designs. I have THIS EXACT DESIGN working, and I literally have a boxed one on my pedalboard right now that is working. I don't think the problem is with my board, unless this particular board has issues, which would be disappointing as they were supposed to have full electrical testing.
"I'm not sure what "serious design flaws" you see. Does it explode or poison your dog?" - PRR

www.sushiboxfx.com

octfrank

Re: How Many Bad FV-1's In a Batch?
« Reply #21 on: April 10, 2020, 01:46:00 PM »
What do X1 and X2 look like when it is not operating properly? Frequency?
Frank Thomson
Experimental Noize

vigilante397

Re: How Many Bad FV-1's In a Batch?
« Reply #22 on: April 10, 2020, 02:00:13 PM »
My oscilloscope is in my office at work which I'm currently locked out of (non-essential worker), but if I find a reason to go in sometime soon I'll probe the board and let you know.
"I'm not sure what "serious design flaws" you see. Does it explode or poison your dog?" - PRR

www.sushiboxfx.com

free electron

Re: How Many Bad FV-1's In a Batch?
« Reply #23 on: April 10, 2020, 04:50:30 PM »
To be 100% sure the clock is not the source of the problem i'd try to:
- remove the xtal + caps
- generate a 32kHz 3.3V square wave externally
- feed it into the pin X1/clock input (10).
There are many ways to create the clock signal: 555 timer (low voltage version), two cmos inverters + crystal (basically replicate a typical circuit which is built in the FV1) or even a 3.3V version of arduino with one pwm channel set to 32kHz 50% duty.

Also, it is recommended to add a small 100n ceramic caps close to the input and output of the voltage regulator to ensure it's stability. Long shot, but maybe the combination of factory tolerances of the chips makes the vreg oscillate and pollute the supply voltage creating the distortion at low levels.

Have you checked the DC bias voltages on audio in and outs? Compared them with working unit?