User Manual
13 
4.1.4  Using Both Main and Auxiliary Outputs 
The power supply has a main output in the rear and an auxiliary output in the front 
that can be used separately or together. 
The main and auxiliary output both share the same voltage and current control knobs 
and will output the same voltage and current up to the maximum output ratings of 
the power supply and terminals. When using both the main and auxiliary outputs 
together, the power supply will automatically total the currents supplied to both 
terminals up to the current limit of the power supply and show the total current on 
the display. 
For example, setting the voltage and current outputs for model 1688B (1-18 V, 0-20 
A) to 18 V and 20 A would output 18 V at both main and auxiliary terminals and allow 
you to draw up to a total of 20 A between the two terminals. If there is a 5 A load at 
the auxiliary terminal, the most current you can draw from the main output is 15 A. 
If the power supply reaches its set current limit at any time, the power supply will go 
into CC mode and the loads together will draw up to the total value of the current 
limit. Distribution of current between the main and auxiliary terminals will vary 
depending on the loads. 
Note:  1685B: Total rated current (Aux. + Main) is 5 A 
1687B: Total rated current (Aux. + Main) is 10 A 
1688B: Total rated current (Aux. + Main) is 20 A 
4.2  Control Modes 
There are four different control modes for the power supply: 
•  Normal 
•  Preset 
•  Set 
•  Remote Control 
To select a mode, slide the Mode Selection Switch on the rear of the unit. 










