Howdy!
Just built a 1114 and a 1222.
Went to do the calibration for the 1222 and I couldnt figure out why the tuner was flickering all over the place and then just went to an _ underscore at octave positions 3 and 5.
When I actually plugged in the VCO out into my interface to my surprise… it stopped making noise at both positions!
It was like a quick pitching down into nothing.
Moving it back to 1 2 or 4 immediately brings the oscillator back!
I honestly dont even know where to start here as in terms of DIY i’m just a humble kit builder.
I have a multimeter and the voltage is 3.996. pretty damn close!
any and all input is welcome!
Welcome to the forum!
How do the connections to pins 3 and 5 on your octave switch look? What about the pins on the Molex connector? I suspect that the 3 and 5 positions aren’t making contact somewhere, or perhaps that the internal connections in the switch are damaged. I had the same descending pitch thing happen when I forgot to put in the locking washer and turned the octave switch past the highest position which had nothing connected.
I’ve also damaged a rotary switch before by applying too much heat when soldering the connections to it. I just checked the spec sheet on the ones I use from Tayda and they’re not supposed to exceed ~350 °C for more than 3 seconds at a time when manually soldering, and I likely exceeded that time limit by quite a bit. Whoops!
Are you able to check for continuity between the center pin and the other pins when you have the switch turned to those positions? If positions 3 and 5 don’t check out, you probably need to replace the rotary switch.
certainly check the connections on the switch, molex and pcb , idealy tone them for continuity.
The resistor ladder must be okaish , but measure the voltage on the common wire on each step.
Rob
I just noticed the subject line says “1222 via Thonk”. Is this the Eurorack version of the 1222? That might go together differently than the Kosmo version. Does the rotary switch connect to the PCB via a Molex connector? Did you have to solder the resistors or did they come pre soldered?
It’s still the case you need to check switch functionality and connection to the PCB but the details may differ if it’s the Eurorack one.
Thank you @analogoutput @illucynic and @twinturbo for the replies. Apologies on the late reply, life got in the way.
At the bench and I have continuity between the inner point and the out points for each position.
Indeed it’s the eurorack version so here’s what I’m looking at
Electronics noob here but if I’m getting continuity within the pot itself in each position, that seems to indicate that the pot is not damaged/faulty and the problem lies elsewhere. What would be the next thing to check?
It’s a little tricky to know exactly as it’s the Euro version so we don’t readily have the schematic. However, the next port of call would be to find the OP amp that get the power from the switch, Check the voltage in each position. It’s a TL074 and was U1A on the original design, It’s just a buffer so the output should be the same as the input. and then pin 13 on the 3340…
Also check all the voltage and ground rails on the IC’s