SL-1176 Power supply Calibration

Adjusting the voltage rails

The power supply PCB has five output headers J-2, J-3, J-4, J-5 and J-6 not all of which are used in the mono version of the SL-1176-KIT. To make the power supply calibration procedure a safer process, you may want to consider making a "measurement harness," basically a break-out cable with tinned wires on one end and receptacle (female connector) on the other. This will minimize the chance of a probe slipping and shorting out a voltage rail.

Set your analog Volt-Ohm-Meter (VOM) or Digital-Volt-Meter (DVM) to read DC Volts. Connect the negative probe of the VOM / DVM to pin-1 of ANY of the output headers, J-6 being the left-most header. It may help to clip an alligator lead to the VOM / DVM probe. If you do, make certain that the alligator clip does not touch any of the adjacent pins. Doing so will result in a dead short on the voltage regulator and could damage the power supply. 

With a small flat blade screwdriver in one hand and the positive VOM / DVM probe in the other:

  • Carefully probe pin-2 of any header to measure the 10-volt rail. Turn RV-2 counter-clockwise (CCW) to make the voltage more negative; CW rotation makes the voltage more positive. Stop turning when the voltage reads "10."
  • Move the positive VOM / DVM probe to pin-3 of the header. This will be the +30V rail. Adjust RV-1 until it reads +30 V. Again, CCW decreases voltage and CW increases voltage.
Until all of the modules are plugged in, it is not necessary to get super precise voltages. This procedure is simply to confirm proper operation of each regulator. You will be re-adjusting both rails when all modules are plugged in and powered up.