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How depressing! My VCF doesn't work all the time. Who can he
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How depressing! My VCF doesn't work all the time. Who can he

by supercaby on Wed Oct 14, 2020 1:19 pm

Hello everyone,
Recently, I'm making a x0xb0x, and I have completed the VCO part. It seems that it has worked. I tested Pin1 and PIN3 of S1 with oscilloscope, and got these two waveforms, which should be correct.
01.jpg
PIC1
01.jpg (116.59 KiB) Viewed 449 times


However, when I went to the VCF part, I had trouble. It didn't seem to work. I couldn't detect any waveform at VR4. I didn't have high impedance headphones, so I used a speaker with a power amplifier, and there was no sound.
So I used the oscilloscope to test the pins of Q12 and Q22, and got the following waveform.
In DC, I could only detect a straight line, so I switched to AC.
02.jpg
PIC2
02.jpg (214.88 KiB) Viewed 449 times

03.jpg
PIC3
03.jpg (167.65 KiB) Viewed 449 times


Each pin of q21 can not detect the waveform, which is almost a straight line.

Voltage of each pin of Q12:
1 - 5.33V
2 - 9.59V
3 - 4.81V
4 - 9.59V
5 - 5.33V

Voltage of each pin of q22:
1 - 11.15V
2 - 11.68V
3 - 11.66V
4 - 11.68V
5 - 11.15V

Voltage of each pin of q21:
1 - 2.73V
2 - 2.15V
3 - 2.12V
4 - 2.14V
5 - 2.73V

The gap between q21 voltage and reference voltage is too large, so I took it down and measured q21 pad voltage as follows:
1 - 5.28V
2 - 11.64V
3 - 0.61V
4 - 11.58V
5 - 5.28V

By the way, I can't buy 2sc1583 and 2sc2291. I replaced 2sc1583 with pmp4201 and 2sc2291 with two bc337a.

This is my current situation. Who can help me?

supercaby
 
Posts: 4
Joined: Mon Oct 05, 2020 12:12 am

Re: How depressing! My VCF doesn't work all the time. Who ca

by supercaby on Mon Oct 19, 2020 2:36 am

This has been solved.


##THREAD CLOSED##

supercaby
 
Posts: 4
Joined: Mon Oct 05, 2020 12:12 am

Please be positive and constructive with your questions and comments.