# Arachnid v2.1 doesn't work



## msgre (Jan 19, 2020)

Hi guys.

I have problems with Arachnid v2.1. It seems that only analog part work since volume and mix knob react to input signal (i can hear original sound when mix is turned to left position and none on right; volume works as expected).

I changed 3 times crystal and 22pF capacitor, now I connect it directly on FV1 to avoid problems with too long wirings (because my first thoughts was that chip doesn't work due to missing CLK). I checked voltage changes on resistors R7, R16, R17 (they vary from 40-200mV to 2.9-3.2 according to selected position of mode switch). I checked input signal on pins 1, 2 (present), but none on 27, 28. I checked grounds & Vcc on all FV1 & EEPROM pins, everything seems OK (according to scheme).

There were only one suspisious thing -- the LED shine (very dimmed) also when footswitch was turned off. So I remove it, connect in/out directly to board and between ground and SW pins put simple switch. Now LED works as expected (no light when switch is open). Probably some problem with wiring on footswitch.

Anyway, I still can't here any sound from FV1. Any thoughts what could be wrong?

Thanks!


----------



## phi1 (Jan 19, 2020)

Post a pic of the board and a close up of the fv1.  Some people have ended up with a fake fv1 chip the fake chip may or may not look different from a real one). Where do you get yours?


----------



## msgre (Jan 20, 2020)

Hi phi1, I ordered it directly from pedalpcb.com e-shop.


----------



## phi1 (Jan 20, 2020)

Maybe try grounding pin13 of the fv-1. This will access the internal patches stored on the fv-1 chip instead of the external eeprom. This will check if the issue is in the fv-1 or the eeprom chip. 

The easiest way to ground pin 13 would be to hook a wire onto the leg of R5, and connect that wire to ground. Make sure you get the leg that goes to pin13, not the leg that goes to 3.3v.


----------



## msgre (Jan 20, 2020)

Tried, but still no signal on output.


----------



## zgrav (Jan 20, 2020)

use an audio probe to confirm you have audio signal reaching FV-1 on pin 1 and 2, and audio signal leaving FV-1 on pin 28.  if you have audio going in to the FV-1 but no audio output, make sure you have power and ground on FV-1.


----------



## msgre (Jan 20, 2020)

I bought cheap chinesse single channel osciloscope, connect Archanid to phone output and feed it with 1 kHz signal. I can confirm that signal is present on pin 1 and 2, but there is nothing on 28 & 27 pin. I checked +3.3V and GND on FV1 pins and dint find anything wrong (pins 4, 7, 11, 12, 19, 24, 25 on GND, pins 6, 8, 23 on +3.3V). I also checked pins 9 & 10 and I can't see any clock signal from crystal (but I am not sure if my oscilloscope probe can't affect somehow resonation).

So my conclusion is that either crystal or FV1 chip is wrong.

Is there anything else I can check or try?


----------



## zgrav (Jan 20, 2020)

I see one connection on your capacitor is to pin 9 on the FV-1.  where does the other lead on the capacitor connect?  looks like it should go to pins 11 & 12.


----------



## msgre (Jan 20, 2020)

Capacitor is connected between 7 and 9, crystal between 9 and 10. Pins 4, 7, 11 & 12 are all connected to GND, so I choose 7 because it was easier to connect to. Before I attach it to chip it was soldered on appropriate position on pcb.


----------



## zgrav (Jan 20, 2020)

Seems like a problem with the FV-1 chip.


----------



## Chuck D. Bones (Jan 20, 2020)

You should be able to see the 32KHz clock signal on pin 9 with your scope.  There is no need to attached the XTAL & 15pF cap directly to the FV-1 leads.  Check every FV-1 solder joint under high magnification.  It is very easy to get a bad connection when lap-soldering gull-wing parts and very hard to see them visually.


----------



## captainmint (May 16, 2020)

Hi, did you solved this problem? I'm experiencing the same issue.


----------



## Eminentfront (May 17, 2020)

captainmint said:


> Hi, did you solved this problem? I'm experiencing the same issue.


I had to replace my FV-1 chip. I think it got burned, because one of the pins was accidentally connected to 9v for a very short while.


----------



## captainmint (May 17, 2020)

Eminentfront said:


> I had to replace my FV-1 chip. I think it got burned, because one of the pins was accidentally connected to 9v for a very short while.


thanks！


----------



## msgre (May 18, 2020)

captainmint said:


> Hi, did you solved this problem? I'm experiencing the same issue.



No, I didn't solve it (I followed instructions displayed here, but I don't find any reason). Arachnid doesn't work.


----------



## captainmint (May 18, 2020)

msgre said:


> No, I didn't solve it (I followed instructions displayed here, but I don't find any reason). Arachnid doesn't work.


sorry to hear that. Mine is also not working properly, same as yours. I'm waiting for my components for audio probe to come. 
I think it might be the fv-1.


----------

