Open Theremin V3, volume oscillator not working

I didn’t say that it was your fault, I’ve already seen full batches of wrongly labeled components which were sent to me by a renowned distributor. That’s why I check every single component with a RLC-meter when building circuits by hand.I pointed you towards the 6 most crucial components which I would unsolder and check, first.The 4060 ICs (U2 and U3) can be simply checked with an oscilloscope and a frequency counter: Pin 7 of U2 should show a square wave with 5Vp and 500kHz, Pin 7 of U3 the same but at 460.7kHz. If both these are ok, you have several confirmations: 1.) The reference oscillators work both as expected and 2.) The problem is really with both analog LC oscillators and you should proceed as I wrote above. If both these weren’t ok (what I think is very improbable) please write back with the results of your measurements.

My pin7 of U3 is 8.4KHZ,After replacing some original parts that do not meet the accuracy standard, it becomes 3.6khz. Which original values do I need to test? I checked them and they all seem to be right

I have built many v3s and encountered many problems. Usually correct automatic adjustment, serial port output will be two digits. If not, there is a problem. As for the situation that the volume does not change, what I have encountered is that the ic4060 is damaged. I haven't found the real reason for the problem that can't be adjusted automatically. I check all the components one by one, and they are all OK. When I replaced the PCB, everything was OK. If you need, I can provide PCB manufacturing documents. I have made some modifications to the original version and removed unnecessary pads.

Hi, I just made a Theremin and I find out that I can't control the pitch antenna. Only if I touch the antenna the sound change. I check the calibration data and it says  "Frequency tuning range: 0 to 0". Do you know how to test the Theremin? Thanks a lot!

I have built many v3s and encountered many problems. Usually correct automatic adjustment, serial port output will be two digits. If not, there is a problem. As for the situation that the volume does not change, what I have encountered is that the ic4060 is damaged. I haven't found the real reason for the problem that can't be adjusted automatically. I check all the components one by one, and they are all OK. When I replaced the PCB, everything was OK. If you need, I can provide PCB manufacturing documents. I have made some modifications to the original version and removed unnecessary pads.Hi, I just made a Theremin and I find out that I can't control the pitch antenna. Only if I touch the antenna the sound change. I check the calibration data and it says  "Frequency tuning range: 0 to 0". Do you know how to test the Theremin? Thanks a lot!

Having just been down this route and finding this post from last year, I thought I'd add some troubleshooting that might help you.

For me, it turned out to be a short due to the mechanical connection of the antenna holders. I had 1.7V on one antenna, and a few mV on the other.

First thing to do: Remove the antenna holders completely and re-calibrate - if you get good calibration values, this is the problem.

When re-attaching the antenna holders, they have a 'spur' on the inside which can dig into the circuit board and cause a short circuit - it's helpful to install these spurs facing out (away from the circuit board). If you've already scraped your circuit board, it may be necessary to apply some electrical tape or other insulator to keep a short developing there again.