VCO Troubleshooting SLMS MKII

[miko667]

Hello and happy new year to all,
Michel, 63, i live in France
i'm new with this forum and newbie with synth diy, but not with electronics.
I've built a SLMS MKII, with some worries... first, i bought fake PN4391 from china, they was mosfet not N JFET.
Found this and swap with MPF102. schematics by R.W. says ok. U3 is OP275, it's seems good too.
I got sound, with the 2 VCO's but the frequency is not stable, varying in 5%.
Tracking is very bad,built and calibrated the Volts Per Octave Calibrator from MFOS too, works well, accurate at 0.002V.
purchased 2N3904 pairs from Soundtronics.
Triple checked resistors values.
some sanity check values are not good (see attachment).
positive rail is 11,3V negative -12V maybe a problem somewhere? without load, PSU give 12V and -12V.


Thanks for the advice

Michel

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soundlab_VCO_values.pdf
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[miko667]

The solution was in the statement...
the tranny used was 24V CT, i was thinking that it was enough for feeding the regulators...
With a 36V CT, it's much better.
Let's go calibrating now