# No wet signal on Arachnid



## DocFlo (Dec 8, 2019)

I am not getting any wet signal from FV-1. I checked Tl074 and it works fine, I've also tested if the signal passes from pin 28 of FV-1 to the output (probed guitar signal directly to pin 28). I also made sure pins are not shorted and that 3.3 V is supplied. I assume oscilator might not be working or the FV-1 is is bad (both were bought from Musikding). Also EEPROM is not connected.

Edit: when I touch program select switch I can hear a loud pop coming from my amp.


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## phi1 (Dec 8, 2019)

Couple ideas, have your guitar go into the input and check for signal at fv-1 pin 1 (input to the fv-1.

also, maybe the eeprom not being connected is the problem. I don’t know the fv-1 behavior when no eeprom chip is connected, it will either pass clean signal or be quiet.   If you don’t have an eeprom chip handy but still want to test, you can ground fv-1 pin 13, which activates the programs installed directly on the fv-1. You could use a multimeter To determine which side of R5 connects to pin 13 and hook a wire onto that resistor leg.


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## phi1 (Dec 8, 2019)

Also, what do you mean by “touch the program select switch”? Touch the shaft with you hand (it’s plastic so nothing should happen), or touch the pins with a probe?


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## DocFlo (Dec 8, 2019)

Touch the plastic shaft with hand.


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## phi1 (Dec 8, 2019)

Hmm. Again, since it’s plastic that doesn’t really make sense because the shaft is plastic, unless touching it actually causes some movement and somethings shorting or there’s a bad solder joint.

study the schematic to understand how the program selector switch works. There are three fv-1 pins that are either ground (0) or 3.3v (1) depending on the switch position. This makes eight possible combinations (binary 000 through 111). Check for voltage on the corresponding fv-1 pins to see if it matches what it should at each switch position.

also, visually inspect to see if you can determine why there’s a pop when you touch theplastic shaft.


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## DocFlo (Dec 8, 2019)

Thanks for suggesting to ground pin 13 to the ground because now chorus program is working and so I can confirm that both oscilator and FV-1 work. 

Also there isn't any pop from touching the shaft (might be a capacitor that didn't discarge). 

When I have the pin 13 grounded I can't sellect any other program by turning the select switch.


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## Robert (Dec 8, 2019)

The rotary switch should still change modes when running the internal programs. 

Rather than try to measure directly on the pins of the FV1, check the DC voltages on resistors R7, R16, and R17 to see if they vary depending on the position of the rotary switch.


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## DocFlo (Dec 8, 2019)

I've mesured DC voltages on suggested resistors but there isn't any segnificant difference (around 1 mV). I assumed this isn't normal and checked continuity between middle and other pins  of the switch and there is none whatsoever.


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## DocFlo (Dec 8, 2019)

I have located the problem regarding the program select switch: the switch isn't working (that also explains the pop). I also figured out that my EEPROM wasn't programmed correctly and solved that problem too.

Thanks to both of you for your time and help!


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## Milos38 (Dec 9, 2019)

I think I may have a dodgy switch on mine. I get intermittent signal from certain positions, otherwise popping when they don’t work. I might reflow the joints and try again. I built another one though with no problem, fires perfectly in each position, I am giving that one to my dad so I still want to get my one fixed. Thanks for the info above I’ll have a look and see what I get.


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## Milos38 (Dec 9, 2019)

I have figured out if I push down harder on my switch as I turn it, it changes through all the modes. Not ideal but I can work with it. Continuity is good in switch positions as I rotate through. Still confused about the switch and having to add force downward as I turn it to get it to work. All pins are correct, unless there is some other point on the base that needs to connect with the pcb?


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## phi1 (Dec 9, 2019)

Just the 9 pins need soldered to the pcb, no other connection from switch is needed. Sounds like maybe the switch supplier made a bad batch.


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