Bunn FMD-5, FMD-4 service manual Disconnect the dispenser from the power source

Tank Heater Relay Control Circuitry (Control Board #2)(120V dispensers only):

1.Disconnect the dispenser from the power source.

2.Disconnect the six pin connector from J3 of con- trol board #2.

3.Check the voltage across pins 5 & 6 of the six pin connector on the wwiring harness with a voltme- ter. 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 control board #2.

6.Disconnect the four-pin connector from J4 of control board #2.

7.Check the voltage across pins 1 & 4 of the four-pin connector on the wiring harness with a voltmeter. The indication must be 120 volts ac.

8.Disconnect the dispenser from the power source.

If voltage is present as described, proceed to step 9. If voltage is not present as described, refer to the wiring diagram and check the dispenser wiring har- ness.

9.Reconnect the four-pin connector of the wiring harness to J4 of control board #2.

10.Check the voltage across the coil terminals of the tank heater relay with a voltmeter. Connect the dispenser to the power source. The indication must be 0 volts ac.

If voltage is absent as described, proceed to step 11. If voltage is present, replace the control circuit board #2.

11.Place containers below any three dispenser nozzles.

12.Simultaneously initiate dispenses at each of the selected dispense stations while monitoring the voltage across the coil terminals of the tank heater relay. The indication must be 120V ac.

If voltage is present as described, the control board #2 is functioning correctly.

If voltage is not present as described, replace the control circuit board #2.

Removal and Replacement:

1.Disconnect the three plugs on the main wiring harness from the connectors on the control board.

2.Remove the four #6-32 keps nuts securing the control board to the component bracket.

3.Remove control board and discard.

4.Install new control board on the component bracket using four #6-32 keps nuts.

5.Reconnect the three plugs on the main harness to the connectors on the control board.

NOTE: J4 is not connected on Control Board #2 on 120/208 - 240V dispensers.

CONTROL BOARD #1		J3	J1
J3	J1
			J1
			J2
			J4
			J3
	J1
	J2
	J4
			J4	J2
	J3
			CONTROL BOARD #2
	J4	J2		P2637
	FIG. 12 CONTROL BOARD CONNECTORS

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