Strange loss of signal behavior

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michaeleschuler

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I put together a The Shining-themed pedal enclosure for a friend with the intent of building a simple circuit from scratch to go in it--whatever he wanted. Unfortunately he finally decided on an analog chorus, which is well beyond my scratch-building capacity. So I shoehorned in a Aion Azure (CE-2) board, putting the 3PDT daughter board components on vero to accommodate the DPDT key switch. Two pots are also relocated to accommodate the existing enclosure design. (I understanding the wire routing may be suboptimal.)

When I powered it up, I got no signal with the switch engaged. When I traced the DC voltages nothing looked obviously wrong. I also checked continuity between off-board components and everything seems OK there.

When I trace the circuit with an audio probe, I get an audio signal through the pedal when it is off. However, when the switch is engaged, I get no audio signal at all--even when I have the probe on the tip of the audio-in cable (completely bypassing the pedal circuit). The only think I can think of is that the switch is connecting to ground and shunting the audio signal from the input jack. But if I check continuity between the tip and ground with the pedal completely disconnected, I don't find any connections.

Does anyone have any thoughts?

Room237Outside.jpg Room237Inside.jpg
 
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Nostradoomus said:
if you have a datasheet for the switch and a layout for the vero daughterboard handy that would be good. If voltages are okay it sounds like a switching issue.
Click to expand...

Thanks! Attached is the daughterboard diagram and a schematic indicating the daughterboard components. The switch data sheet I got from Mouser ( https://www.mouser.com/datasheet/2/240/aswitchlock-3051061.pdf ).

I am pretty certain I checked all of the soldering on the daughterboard for bridges and other issues, but will check it again. I'll also see if I can troubleshoot the switch. I get a ground connection on the retaining nut, not not on the key or other accessible metal parts.
 

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  • Azure_schematic.png
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GAStan said:
The switch's solder lugs don't seem to match anything on that datasheet. Do you have the part# of the keyswitch?
Click to expand...
My apologies--I see now that I referenced the wrong data sheet; the model I use is Y201132C803NBE, and the datasheet is
https://www.littelfuse.com/assetdoc...ssetguid=fac8b3c9-5f06-4014-8ee0-537b6c022b2d

I've checked the contacts on this data sheet and the pedal switch appears to follow the proper wiring (5 to 4 to 8 to 1 for bypass and 5 to 7 and 1 to 3 to route through the daughterboard).

I do see now that the switch is anti-static, but will have to evaluate if this would have any effect.
 
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Actually, the "C" in the middle denotes a non-antistatic switch. A "R" or "W" would be antistatic.

It looks to me like the switch is wired correctly.

If it were me, I would unsolder the blue and white wires from the switch, take it completely out of the circuit. Connect blue to blue and white to white to test the pedal. If pedal works then it has something to do with the switch. If pedal doesn't work it's the problem.
 
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