INSTRUCTIONS \ SY-1 \ general information

Let’s build a Syncussion!


Rev 2 information
The second run boards features the quiet diode™ mod. To remove the ever present noise coming from the -8V.
To reverse the mod to an original SY-1 — Remove the diode and jumper pin 6 and 8 on the TL497.


Errors on board first run, this has been fixed in the 2nd run. Unfortunately we have a few mishaps on the PCB, nothing major, but it’s nice to be aware of when building.



  • Board 1, The pinout of the noise transistor is wrong. It’s labeled as EBC from top to bottom, but it should be CBE instead. A BC547 will fit with the silkscreen and work well.


Skärmavbild 2016-06-17 kl. 14.00.27


  • Board 1, The rate slider for the LFO might kill the LFO when it’s at bottom. Increase the 470Ω resistor next to it to something between 560Ω and 1k depending on your preference. This might not affect all builds.


  • Board 2 & 3, Four resistors are marked with the wrong value – 100k and 47k instead of 22k! See image for their location, it shows the values to install.


Skärmavbild 2016-06-17 kl. 13.55.42


Skärmavbild 2016-06-17 kl. 13.55.31


Another thing is that there’s some components with the suffix as a prefix – E.g. u47. So to make it clear here’s what it means –
u47 = 0.47u = 470n
4u7 = 4.7u
47u = 47u

The transistors should be matched for Vbe.

So with that out of the way we can start building!

It’s a straight forward build, no funny components and not any challenging mechanical things. I do recommend you build the PSU first and test it, and then build the rest of the board. Since it’s 2 channels and they’re both the same you will be building everything twice. Only exception is noise and PSU of course.


Syncussion BOM


Syncussion overlay



I’ve divided the build to three sections –

Board 1  – This is the front panel board which houses sliders and other front panel components. It also contains the PSU, noise source, LFO, Sweep, and S&H circuits.

Board 2 & 3 – These two boards are connected with V-cut. You can snap them appart if it simplifies the building for you (Though I would recommend against it). They might best be described as the voice boards. And holds the mode switching circuitry, VCOs, filter, and VCA.

Finishing up – Let’s assemble it! Screws, nuts and bolts.


Let’s roll!

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