Bunn H5E Operating & Service Manual page 14

SERVICE (cont.)
Electronic Controls (cont.)
Electronic Controls Removal and Replacement
NOTE - Each electronic control assembly is calibrated to
a temperature sensor probe. Both components MUST
be replaced as a set.
1. Remove all wires from the electronic control as-
sembly terminals.
2. Remove the two 8-32 screws holding the electronic
control assembly to the component bracket.
3. Disconnect the temperature sensor, overflow tube
temperature sensor, and indicator wires from the
left side of the electronic control assembly board.
4. Remove the temperature sensor from the grommet
in the tank lid.
5. Install the new temperature sensor into the grom-
met on the tank lid. Route the wires to the location
of the new electronic control assembly.
6. Attach the temperature sensor, overflow tube
temperature sensor, and indicator wires to the
electronic control assembly.
7. Fasten the new electronic control assembly to its
bracket.
BLU to Triac Assy
WHI/BRN to Tank Heater Switch
TAN to Triac Assy
PNK to Liquid Level Probe
WHI or RED to Terminal Block
BLK to Overflow Safety Switch
GRN or GRN/YEL to Chassis Ground
WHI/BLU to Solenoid
FIG. 3 WIRING CONNECTIONS
WHI & WHI to
Temperature Sensor
PNK & GRY to
Heater Indicator
Refill Indicator
Power Indicator
Ready Indicator
GRY & GRY to-
Thermistor
FIG. 4 WIRING CONNECTIONS
8. Reconnect the wires.
9. Review the initial set-up procedures.
Triac Assembly Removal and Replacement
NOTE - Each triac installation requires the use of an
approved silicone heat sink compound. Bunn-O-Matic
recommends the use of Dow Corning 340 compound
or equivalent. It can be purchased direct from Bunn-
O-Matic (part # 12572.0002).
1. Place the tank heater switch on the electronic con-
trol assembly in the "OFF" position.
2. Completely drain the tank.
3. Carefully set the dispenser on its face (faucet
side).
4. Remove the four feet attached with four 8-32
phillips-head screws.
5. Remove the bottom panel and four feet attached
with seven 8-32 slotted-head screws.
6. Remove the existing triac assembly held in place
with a 10-32 hex keps nut.
7. Apply a small amount of the silicone heat sink
compound to the copper heat sink.
8. Securely fasten the new triac assembly to the bot-
tom of the tank in the same relative position as the
one removed. Bunn-O-Matic recommends tighten-
ing the nut to a torque setting of approximately 18
inch-pounds.
9. Route the wires up around the rear of the dis-
penser.
10. Reinstall the bottom panel and four feet.
11. Stand the dispenser upright.
12. Disconnect the other ends of the old triac assembly
wires.
P1774
13. Connect the TAN and BLU wires with spade termi-
nals of the new assembly to the electronic control
assembly, FIG. 3.
14. Connect the BLU wire with the ring terminal to the
tank heater, FIG. 13.
15. Connect the WHI/VIO wire of the new assembly to
the WHI or RED terminal at the terminal block.
P1774
14
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