SERVICE (cont.)
CONTROL BOARD and LEVEL PROBE (cont.)
Test Procedure:
Low Product Detect
1.Disconnect the dispenser from the power source.
2.Disconnect the twelve pin connector (J1) from the control board.
3.Check the voltage across pins 2 & 3 of the twelve pin connector on the wiring harness with a voltmeter. Connect the dispenser to the power source and select the “ON” position of the main power switch. The indication must be 24 volts ac.
4.Select the “OFF” position of the main power switch and disconnect the dispenser from the power source.
If voltage is present as described, proceed to #5.
If voltage is not present as described, refer to the wiring diagram and check the dispenser wiring harness.
5.Reconnect the twelve pin connector to the control board (J1).
6.Disconnect the four pin connector (J6) from the control board.
7.Check the voltage across pins 1 (positive) & 3 (negative) of the four pin connector on the control board with a voltmeter. Connect the dispenser to the power source and select the “ON” position of the main power switch. The indication must be +5 volts dc.
8.Select the “OFF” position of the main power switch and disconnect the dispenser from the power source.
If voltage is present as described, proceed to #9.
If voltage is not present as described, replace the control board.
9.Reconnect the four pin connector to the control board (J6).
10.Check the voltage across pins 1 (positive) & 3 (nega- tive) of the four pin connector on the control board with a voltmeter. Place a full hopper in the dispenser, connect the dispenser to the power source, select the “ON” position on the main power switch, and close the dispenser door. The indication must be +5 volts dc.
11.Disconnect the dispenser from the power source, remove the jumper wire, and select the “OFF” posi- tion on the main power switch.
If voltage is present as described, proceed to #12.
If voltage is not present as described, replace the photo transistor.
12.Check the voltage across pins 1 (positive) & 3 (negative) of the four pin connector on the control board with a voltmeter. Remove the hopper from the dispenser, connect the dispenser to the power source and select the “ON” position of the main power switch. Shine a flashlight on the photo transistor (left side panel). The indication must be less than 1 volt dc.
13.Disconnect the dispenser from the power source and select the “OFF” position on the main power switch.
If voltage is present as described, proceed to #14.
If voltage is not present as described, replace the photo transistor.
14.Disconnect the two pin connector (J2) from the control board.
15.Check the voltage across pins 1 (positive) & 2 (negative) of the two pin connector on the control board with a voltmeter. Connect the dispenser to the power source and select the “ON” position of the main power switch. The indication must be +1.5 volts dc.
16.Select the “OFF” position of the main power switch and disconnect the dispenser from the power source.
If voltage is present as described, proceed to #17.
If voltage is not present as described, replace the control board.
17.Check the photo LED forward and reverse bias us- ing a diode tester. The photo LED must be forward biased with positive applied to pin 1 of the two pin connector and negative applied to pin 2 of the two pin connector. The photo LED must be reverse biased with negative applied to pin 1 of the two pin connector and positive applied to pin 2 of the two in connector.
If the photo LED biasing checks as described, the low level detect circuitry is operating properly.
If the photo LED biasing does not check as described, replace the photo LED.
NOTE: The photo LED lights in the infrared spectrum and is not visible to the human eye.
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