ARP Axxe VCO

[Analog Art]

Hello everyone.
I dug up this post, I mounted this VCO on veroboard but it doesn't work, no sawtooth or square output, has anyone managed to make it work? I rechecked the assembly and the components, nothing can be done, it doesn't work and I can't find the problem

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[furio]

Hi!

The timing capacitor must be 10pF (CA3046 has a thin/poor sound, CA3086 or dual matched BC transistors will sound fat).

https://www.musikding.de/CA3086_1

[Analog Art]

I replaced the capacitor with a 10pf but nothing works, it still doesn't work, I don't understand anything, I double-checked everything

[furio]

The PCB worked... it's gone because Odyssey is juicier. I would also be interested in a certified stripboard. We had stopped using generic metal film because it sounds thin and blurry. It would be nice to test it again and certify an adequate carbon film strategy for a maximum organic/fat ARP-type sound. This minimalist design doesn't really fit in with the original. It sounds very ARP style.

* It would be interesting to find out if this is a resonance or a manipulation.

If you have been prisoner, drugged and tortured since 2007 by the French secret services... the situation is ambiguous... you cannot know if this is real.

In this stripboard design the euro power supply is missing and the opamps for the buffer adjustment of output levels have not been provided. There is no motivation... if you haven't had PSUs for the synth for 10 years, you should build those first... if you are demanding and LM317 has become poor... it costs a lot of money and work to turn on the synth... months of savings and work.

It should help someone else, or at least be given the original file to check and fix at low cost. If for you 5 hours of work require 3 days of break/relaxation and 200-300 euros of medicinal cannabis... it is too expensive... you will prefer to invest in more practical things, such as cleaning and reorganizing the studio or building new digital transport and extreme converters... it will probably take you all summer to build the converters... you need to be able to monitor, record and listen first to get motivated.

It would be nice to turn the synth back on this year but it's not considered possible.

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[Analog Art]

back on the assembly, it did not work because I had put a 10pf capacitor, with a 10nf it works. It is not possible to have a good calibration of the notes,my transistors are nevertheless well matched, I do not understand why I do not obtain a good adjustment of the notes? I do not know the initial frequency of adjustment of the frequency potentiometer, at what frequency should it be adjusted to obtain a good adjustment of the scale of the notes?

[furio]

With 10pf ceramic disc capacitor for timing and CA3086 3.5 octaves are traceable... perhaps with silver-mica it increases tracking.

Keep the PCB powered on for 30 minutes or more before calibrating (close windows or vents during calibration).

I don't remember... maybe I started with with C2 at the center of the potentiometer (because when calibrating it will move)... if there is a tempco installed and in contact with the differential... it will be possible to play with adjusting two reference notes/frequencies (C2-C4 for example) and when the two frequencies are calibrated the entire scale will be calibrated (20-30 minutes of work).