EDIT: FIXED LOL ONE OF MY PINS WAS NOT SOLDERED WELL ENOUGH AND WAS HIDDEN VERY WELL
For the past three days I’ve been toiling over a single issue with an AS3340 build I’ve been making. The problem is this: The base frequency is too high, at 164hz.
For the record, everything else works. All knobs and inputs/outputs are working as intended and the waves are correct with their proper output voltages. Except for the fact that when the coarse tune knob is turned up, it goes up to 300khz. I’m currently working with all knobs removed. This doesn’t appear to be a problem with the knobs, as the base frequency is 164hz, regardless of whether the knob is attached and turned down all the way, or if it’s detached altogether.
The build is based off of the same one that I had previously made, from this post on the forum The base frequency of the original one I made is ~1hz.
So the whole time I’ve had a 100% fully functional, satisfactorily working, total clone of this VCO to work off of pin-by-pin, physically next to this new VCO. This is to say that there’s obviously some error in my soldering of the new VCO, but several days of redundantly checking for shorts, continuity, comparing voltages of pins, resistances between the pins, etc. have shown that this can only be some cruel joke the universe is playing on me.
I’ve swapped chips between both perfboards. It’s definitely a problem with the way I’ve wired the board, as both of my as3340 chips work in the first VCO build I have, and both have a base frequency of ~164hz in the new one (bad).
I’ve gone so far as to remove everything from the 10k scale trimpot to pin 3, attach pin headers to the perfboard, and rebuild everything on a breadboard attached by dupont wires to try and see if it’s the scale portion of the circuit that’s responsible.
Curiously, when I remove the 10k scale trimpot, nothing happens to the frequency. It remains at a steady 164hz. The frequency doesn’t even flinch in the scope. Furthermore, I’ve tried putting different values of resistor directly between pin 1 and pin 3. The only thing that makes a difference is if I use a value below 24k, which dramatically raises the frequency of the VCO.
I’ve tried lowering the ohms of the 5.6k resistor between pins 2 and 3. I went as low as 4k, which brought the base frequency down to 4hz, but put a sort of kink in the saw wave which indicated to me that I was on the wrong path.
I measured the voltages across all the pins on both VCOs, which appear to be almost identical. At this point, I’m very lost. haha.
The only other place I could think that would be causing trouble is pin 14, the other scale pin, but it’s wired the exact same way as the good VCO. I’ve checked for continuity, resistance, etc.
If for nothing else, I just need to type this out for catharsis, but if anyone has any advice I’ll take it. Happy to answer any questions or try any suggestions as well. Thanks.