Abstrakt Instruments VS-1 Assembly Manual page 14

STEP 11: CALIBRATE PSU OUTPUTS
https://youtu.be/wAF4sgTHIrc
WARNING! Be extremely careful when working with line voltage.
1) Make sure the power switch (rocker switch) is on the off position.
2) Plug in the power cable.
3) Turn on the power switch.
4) Probe the +18.5V raw output from the PSU. Use the ground test point for the ground lead and clip the other test lead to the
appropriate position from the top of the power connector (see PCB silkscreen). Adjust the trimmer on the PSU until the value is
+18.5V +/-0.1V.
5) Next, connect the voltmeter to the +6.5V raw output from the PSU (the front two positions of the connector are +6.5V as shown
on the PCB silkscreen).
6) Now check the -18V output and confirm it's -18V +/-0.3V.
Note: When the PSU trimmer is adjusted the ~6.5V output is also affected. The +18.5V output is the most critical so you will be
adjusting the voltage specifically for the 18.5V rail. The +6.5V output may end up anywhere between 6.3V and 6.8V. This is ok.
7) Probe -15V at the test pad on the PCB. Adjust TM1 for -15V +/- 0.1V (the -15V rail is used as a voltage reference for some
circuitry and should be more precise).
8) Check the fixed +15V rail at the test pad on the PCB. Confirm it is +15V +/-0.3V.
9) Insert IC's (if socketed) and test the analog +/-15V PSU outputs again. You can insert all IC's at once or only a few at a time.
There is no order that the IC's need to be installed, and they can be installed in any number or order.