Bunn FMD-4, FMD-5 service manual Control Board Cont, SERVICE cont

SERVICE (cont.)

CONTROL BOARD (CONT.)

16.Reconnect the ten pin connector of the wiring harness to J2 of control board #1.

17.Gently pull the liquid level probe out of the tank lid and inspect for corrosion. Replace it if necessary.

18.Place the probe so that neither end is in contact with any metal surface of the dispenser.

19.Check the voltage across the terminals of the inlet solenoid valve with a voltmeter. Connect the dis- penser to the power source. The indication must be 120 volts ac for two wire 120 volt models, three wire 120/208 volt models, three wire 120/240 volt models after a delay of approximately 10 seconds.

20.Move the probe’s flat end to the dispenser hous- ing. The indication must be 0.

21.Move the probe’s flat end away from the housing. The indication must, again, be 120 volts ac for two wire 120 volt models, three wire 120/208 volt models, three wire 120/240 volt models after a delay of approximately 5 seconds.

22.Disconnect the dispenser from the power source.

If the voltage is present as described, re-install the probe. The liquid level control circuitry is operating properly.

If the voltage is not present as described, check the pink probe wire and green tank wire for continuity.

Hopper Motor Control Circuitry (Stations 1-3, Control Board #1 & Stations 4-5, Control Board #2):

1.Disconnect the dispenser from the power source.

2.Disconnect the six pin connector from J3 of the appropriate control board.

3.Check the voltage across pins 5 & 6 of the six pin connector on the wiring harness with a voltmeter. Connect the dispenser to the power source. The indication must be 24 volts ac.

4.Disconnect the dispenser from the power source.

If voltage is present as described, proceed to step 5. If voltage is not present as described, refer to the wiring diagram and check the dispenser wiring har- ness.

5.Reconnect the six pin connector of the wiring harness to J3 of the control board.

6.Check that the rinse/run switch is in the run position.

7.Check the voltage across the red (+) terminal and the black (-) terminal of the auger motor with a voltmeter. Connect the dispenser to the power source. Press and hold the appropriate dispense switch. After a delay of about .6 seconds, the indication must be between +4.0 and +24.5 volts dc.

If the voltage is present as described, the hopper motor control circuitry is operating properly.

If the voltage is not present as described, replace the control circuit board.

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