Function Multiplier output offset
Adjust: VR35 for zero (±2µV) on DVM at PROD.
Voltmeter adjustment (external sense).
Connect: Remove the short and connect the High voltage supply to the rear panel Load Input
terminals.
Connect the DVM to the front panel Load Input terminals.
Select: Sense slide switch = external
Meters = Volts & Amps.
Set: Set supply output voltage to 70 Volts on DVM.
Adjust: VR29 for Voltage (LH) display to read 70.00 (or to match actual voltage on DVM).
Internal to External voltage sensing difference test.
Select: Sense slide switch = internal.
Check: Voltage (LH) display reads 69.90 to 70.10 (or matches actual voltage ±0·1V).
Connect: Switch off and disconnect the supply.
Current Calibration
The following tests are in a sequence from high current at low voltage towards low current at high
voltage, to minimize the need to re-connect different power supplies across the range. Stability
depends on the characteristics of the particular supply; most supplies should be satisfactory.
Connect a scope the current monitor output and monitor for signs of instability.
Compare Amplifier offset.
Connect: High current PSU through power terminals of current meter (or shunt) to rear panel
Load Input.
Connect the Sense input that power supply to the front panel Load Input Terminals and
set it up for external sensing.
Connect the DVM between IFB (TP2-b) and DMD (TP3-c).
Preset: Set VR25 fully clockwise.
Set: Power supply output voltage = 3.0 V, Current Limit = >80 Amps. Output off.
Select: Enable = out, Sense slide switch = external.
Slow Start = in. Slew Rate = physical centre, Slew range = low. Dropout = 0 (fully
CCW).
Mode = 80 Amp, Control = Level A, Meters = Level A & Level B.
Set the Level A control so the LH display reads 40.00.
Select: Enable = in. Check that the Input lamp is orange (the source is off).
Set: Supply output = on. Check that the Input lamp is green.
The load should be conducting about 40 Amps.
Adjust: VR24 for zero (±5µV) on DVM.
80 Amp mode setting calibration
Connect: Disconnect the DVM from IFB and DMD.
Connect the DVM to the sense outputs of the current shunt, if used.
Adjust: VR25 for current to be 40.00 Amps (measured by meter or DVM across current shunt).
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