Specialty Concepts SCS/90 - Manual (Page 22)

B E N C H T E S T P R O C E D U R E : S C S
This procedure provides a basic bench test to check the operation and calibration for the SCS.
This procedure is designed specifically for experienced electronic technicians.
Equipment required: Digital multimeter: 0-80 volt 500 ma power supply
The SCS printed circuit board is coated with a water resistant coating. Use a sharp pointed
probe and enough pressure to pierce the coating when making measurements.
1) Inspect temperature compensation sensor and cable for damage. If damaged, the
controller will no longer operate. See TEMPERATURE COMPENSATION section.
2) Make sure there is a jumper between VOLTAGE SENSE (+) and BATTERY (+) and one
between VOLTAGE SENSE (-) and BATTERY (-).
3) Measure the resistance between the BATTERY (+) and SOLAR ARRAY (+) terminals. It
should be open.
4) Check the diodes connected to pins 6 and 7 of the MC1723 IC.
5) Set the power supply to the nominal system voltage (12, 24, 36 or 48 volt), current limit to
500 ma.
6) Connect the power supply (-) to the controller BATTERY (-) terminal. Connect the power
supply (+) to the controller BATTERY (+) terminal and to the controller SOLAR ARRAY (+)
terminal.
7) Measure the voltage at pin 11 of the MC1723 IC. It should be about the power supply
voltage. If it is not, suspect the unit defective and return for repair.
8) Measure the voltage at pin 6 of the MC1723 IC. It should be 7.7 +/- 0.2 volts. If it is not,
unsolder and remove one end of the diode on pin 6 and re-measure. If the voltage is now
correct, the controller should be sent in for repair. If the voltage is still wrong, the MC1723
is bad.
9) If the controller is in charge mode, go to step 9. If it is not, switch on and then off the
ARRAY circuit breaker. The controller should go into charge mode.
10) Measure the voltage across the relay coil (smaller wires). It should be between 8.0 and
13.0 volts. If it is not, suspect the 100 ohm power resistor, Xstr TIP 100(or 102).
11) Verify the set-points by changing the power supply voltage up and down and observing the
activation.
12) Change the CHARGE SET-POINT SELECT switch and power supply to verify other set-
points. Repeat steps 10-11. Refer to the specifications for set-point values.