Troubleshooting a Raygun Youth Fuzz / CD4046

[mdcmdcmdc]

Hello helpful folks,

I built up Fredrik Lyxzén's Raygun Youth Chaos Fuzz project based on his vero layout the other night and have run into some issues. I'm having a bit of trouble tracing the audio path to figure out if there's something wrong with my build (more likely) or if there's something wrong with the CD4046 PLL chip (less likely).

Here's the vero:


Here's the schem:


Position 1 on the switch works fine; I'm getting the same output from pin 1 of the TL062 as I am at lug 3 of the volume pot.
Position 2 gives me no signal
Position 3 gives me a signal that I think is the same as pin 7 from the TL062 (slightly low-passed version of what's on pin 1). "Disorder" control does nothing.
Position 4 gives me nothing

Working backwards, all the connections from the center pin of the switch to the circuit are fine; ie, no bad joints etc. I have continuity in each position.
I have strong signal on pin 14 of the CD4046, and that's where things go sideways, and where my knowledge gap of what that chip is actually doing, and where I should be probing to hear signal (and not hearing it).

I'll pull voltages later today, but any guidance on where I should be able to get a clear signal out of that chip would be really helpful in terms of troubleshooting. It's a fairly low parts count and I've already double checked component value and placement, scraped the tracks for bridges, etc. The ICs are seated properly in sockets. No part subs other than a 25K vol pot instead of 20K, which I can't imagine is causing issues.

Unfortunately I only bought one of the CD4046 chips so I can't easily do a swap test without a trip to the arduino shop!

Thanks in advance as always!

[anotherjim]

CD4046
Is pin 5 grounded to 0v? It must be.
C5 connected across pins 6 & 7 and no shorts to anything else?
Pin 9 not 0v when signal present at pin1?

[mdcmdcmdc]

Pin 5 goes to ground, confirmed at the power source.
The only pins on the CD4046 where I'm getting signal are 2 and 14.
Checked continuity across the board and pins 6&7 are connected only to each other via C5 and not connected to anything else.
Pin 16 is seeing a bit under 9v
Pin 9 is showing >0v, it starts around 300mV, slowly drops to around 30-40mV, and then wiggles around a bit.

Just checked to see if there were any shorts between pins on the chip and the only pins that have continuity are 3-4 and 5-8, as per the schem.

The chip is actually getting hot to the touch in the socket, so if it wasn't borked before it probably is now. 

If I can get to the shop tomorrow I'll buy another chip and see if that's the issue.

[mdcmdcmdc]

I'll do another visual inspection in the AM with fresh eyes to see if there's an errant resistor value or misplaced link.

[anotherjim]

Ok, a 4046 should not get hot!
Pin 9 controls its VCO frequency. If close to 0v (yours is) the frequency is too slow to notice, 1Hz or slower.


Signal at pin 2 is just the input from pin 14 getting through the internal logic and doesn't imply anything much is working.

[mdcmdcmdc]

Picked up 2 more CD4046s this afternoon, no change with the chip swapped. The IC heats up noticeably, got a ticking in positions 2+4.

BUT, I just looked at the board with fresh eyes and noticed a trace cut in the wrong spot! I have cut at L-12 instead of J-12 so Pin 15 is connected to 9V and there's a cut blocking signal to the disorder knob. That'd do it, I imagine. As expected, my fault not the chip...

EDIT - jumped the errant cut, put one where it should and everything is working great! Chaos fuzz for sure, 100% dumb fun.

[mdcmdcmdc]

I guess the question is now what to do with these two other CD4046s!