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VCF with scrappy resonance...
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VCF with scrappy resonance...

by diplowave on Wed Mar 13, 2019 6:19 pm

Hi,
It's been several months weeks, i built a x0x which has a problem with the VCF, i left it aside and watch that from time to time ...

Symptoms: the resonance is not going thoroughly, you can not make the vcf go high treeble ... This means that vcf acts bottomless on the accent and the envelope does not affect the VCF, because the resonance is scrappy.

I checked a lot of things, checked all the pcb tracks, checked all VCF resistors and capacitors, replaced all the VCF transistors and checked if they were OK.

By cons i find that at the junction of R111 / Q21, i have about 9.7VDC. Same as the junction of R110 /Q21. It's abnormal, i should have about 6V! And at the junction of Q19 / C14, i have 9VDC, i should have 5.25V! Apparently that's why i have rotten VCF, but i do not understand why these voltages are bad ...

diplowave
 
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Please be positive and constructive with your questions and comments.