MARS MiniNode Current Monitor and Ground Fault Detector Test Procedure

Inspect the blank PCB

Load the parts

Connect the test box and DC power supplies

Turn on DC power supplies +5 +12 -12

Test the current monitors:
  5V 5A PS to each odd/even input pair in turn
  1 Ohm 250W resistor load to each odd/even pair in turn
  5A should produce 2.5V analog output from each NT-5 current monitor
  
Turn off DC power supplies
  
Test Ground Fault Monitors:

  16 Sept 2021
  
  Using the spare loaded PCB
     Connect the test box to the PCB ( three C-Grid 100 plugs )
	 Connect power to the PCB with an external power supply ( +5, +12, -12 )
	 Connect a 350V power supply to J2
	   J2-1 350 Common
	   J2-2 350 VDC
	 Monitor GF1 Voltage ( red banana jack ) on the tester with a DVM with respect to RTN ( brown banana jack )
	 Connect Ground Fault simulating resistors between PCB TP12 ( SWGND ) and 350 VDC ( J2-2 ) and then 350 Common ( J2-1 )
	 
	 GF Sim Resistor      GF Current    Switch OFF GF Volts    Switch ON GF Volts     Difference
	 
     500k                 700 uA        2.518 	               3.789                  -1.271
	                                    2.475                  1.207                   1.268
   
    1Meg                  350 uA        2.518                  3.254                  -0.736
                                        2.475                  1.742                   0.733
				
    4Meg                 87.5 uA		2.519                  2.726                  -0.207
                                        2.475                  2.268                   0.207

										

  Old Stuff:

  Set Up

  Remove the 1 Ohm load from the output
  Tack solder 4 ea 10k resistors in parallel with R1, R2, R3, R4
  Tack solder 1 ea 1.47k resistor in parallel with R5

  GF1
	
  Connect +20V to J2-2; 20V RTN to J2-1
  Turn on DC power supplies and 20V DC power supply
  Connect potentiometer ( marked 20 ) 
    Green wire to TP18
    Yellow wire to SW-GND
    Turn pot CCW
    On test box, monitor "GF1" voltage with respect to gnd fault outputs "RTN"
  With all test box switches off, "GF1" should read approx 2.5V DC
  Turn test box switch "350 C1" on; "GF1" should read approx 2.7V DC
  Turn pot "20" CW; "GF1" should read approx 4.5V DC
  Turn off DC power supplies and 20V DC power supply

  GF2
	
  Connect +20V to J2-3; 20V RTN to J2-4
  Connect potentiometer ( marked 20 ) 
    Green wire to TP20
    Yellow wire to SW-GND
    Turn pot CCW
  On test box, monitor "GF1" voltage with respect to gnd fault outputs "RTN"
  Turn on DC power supplies and 20V DC power supply
  With all test box switches off, "GF2" should read approx 2.5V DC
  Turn test box switch "350 C2" on; "GF1" should read approx 2.7V DC
  Turn pot "20" CW; "GF2" should read approx 4.5V DC
  Turn off DC power supplies and 20V DC power supply

NOTE: Pot "350" is for testing Ground Fault circuitry with 350 VDC
      *** Be absolutely CERTAIN that the test box is well grounded
      during testing with 350 Volts ***  

Remove the tacked - on resistors from R1, R2, R3, R4, and R5.