[HELP]Erica Synth VCO II not working properly..

From circuitbending to homebrew stompboxes & synths, keep the DIY spirit alive!

Moderators: Kent, luketeaford, Joe.

Post Reply
User avatar
Learning to Wiggle
Posts: 46
Joined: Tue Mar 08, 2016 4:20 pm
Location: Sicily(and)Bologna

[HELP]Erica Synth VCO II not working properly..

Post by oppositaer » Fri Feb 08, 2019 5:05 am

Hello there,
here is Ivan, i bought a bundle of DIY pcbs a while ago.. The VCF, MIDI TO CV and SWAMP are working properly..
I am having problem with the VCO II and the EG II.

The oscillator does not output lower timbres, I tried to make any kind of calibration with the trim pot but the lower pitch I get is very high.
To better explain I uploaded a video you can watch on the link below:

Did you ever had any kind of similar issue before? What should I check first? Maybe any of the capacitor? I checked all the soldered components at least ten times but it looks live everything is in place! Also ICs are placed in the right position..

The EG is instead not working.. LEDS are not blinking unless I put some jumper(also a multimeter) between TP4(or TP3) and TP1 (where the lower LED is). In this way I could hear a subtle Gate output but the EG output as well as ADSR parameters are not working at all!
Also the TL074 IC get relatively hot..
For this build I used many resistors with 5% tolerance.. But I guess this ain't a big problem as I did the same for the VCF and the latter works!

Probably I had to make another video for the EG to let you show the problem..
I build DIY kits and projects in South Europe.. PM me if you need help!

Some sounds:

Post Reply

Return to “Music Tech DIY”