Bunn U3 Operating & Service Manual
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Bunn U3 Operating & Service Manual

Bunn u3, u3a operating & service manual
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U3
U3A
OPERATING & SERVICE MANUAL
BUNN-O-MATIC CORPORATION
POST OFFICE BOX 3227
SPRINGFIELD, ILLINOIS 62708-3227
PHONE: (217) 529-6601
FAX: (217) 529-6644
To ensure you have the latest revision of the Operating Manual, or to view the Illustrated Parts
Catalog, Programming Manual, or Service Manual, please visit the Bunn-O-Matic website, at
www.bunn.com. This is absolutely FREE, and the quickest way to obtain the latest catalog and
manual updates. For Technical Service, contact Bunn-O-Matic Corporation at 1-800-286-6070.
10060.0000K 10/08 ©1984 Bunn-O-Matic Corporation

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Summary of Contents for Bunn U3

  • Page 1 To ensure you have the latest revision of the Operating Manual, or to view the Illustrated Parts Catalog, Programming Manual, or Service Manual, please visit the Bunn-O-Matic website, at www.bunn.com. This is absolutely FREE, and the quickest way to obtain the latest catalog and manual updates. For Technical Service, contact Bunn-O-Matic Corporation at 1-800-286-6070.
  • Page 2 SOLE OPTION AS SPECIFIED HEREIN, TO REPAIR, REPLACEMENT OR REFUND. In no event shall BUNN be liable for any other damage or loss, including, but not limited to, lost profits, lost sales, loss of use of equipment, claims of Buyer’s customers, cost of capital, cost of down time, cost of substitute equipment, facilities or services, or any other special, incidental or consequential damages.
  • Page 3 DAMAGE, FIRE, OR SHOCK HAZARD READ THE ENTIRE OPERATING MANUAL BEFORE BUYING OR USING THIS PRODUCT THIS APPLIANCE IS HEATED WHENEVER CONNECTED TO A POWER SOURCE 00831.0000F 3/98 ©1998 BUNN-O-MATIC CORPORATION #00831.0000 WARNING Very Hot Water Use With Care! #12593.0000...

  • Page 4: Electrical Requirements

    CAUTION - The brewer must be disconnected from the power source until specified in Initial Set-Up. L2 RED WHITE NEUTRAL L1 BLACK U3 & U38 requires 3-wire, grounded service rated 120/208 or 120/240 volts ac, U3-30 amp,U38-40 amp, single phase, 60 Hz. Proceed as follows: BLACK GREEN U3A models require 2-wire, grounded service rated 230 volts ac, 30 amp, single phase, 50 Hz.

  • Page 5: Plumbing Requirements

    90 psi (620 kPa) to reduce it to 50 psi (345 kPa). The water inlet fitting is 3/8" flare. NOTE - Bunn-O-Matic recommends 3/8" copper tubing for installations from the 1/2" water supply line. A tight coil of copper tubing in the water line will facilitate moving the brewer to clean the countertop.

  • Page 6: Adjusting Brew Volumes

    INITIAL SETUP (cont.) 6. Brewing cycles may be started whenever water temperature is correct. This condition is indicated by the dial thermometer on front of the brewer. Whenever the pointer is in the green, brewer is ready for brewing. The recommended brewing temperature is approximately 200 turning thermostat knob clockwise, decreased by turning knob counterclockwise.

  • Page 7: Coffee Brewing

    9. Wipe the entire outside surface of the machine with a clean damp cloth. Wipe dry. 1. A filter holder is supplied with each U3 coffee brewer. Its purpose is to keep the filters in their originally formed shape to properly fit the brewer funnel.

  • Page 8: Troubleshooting

    A troubleshooting guide is provided to suggest probable causes and remedies for the most likely problems encountered. If the problem remains after exhausting the troubleshooting steps, contact the Bunn-O-Matic Technical Service Department. • Inspection, testing, and repair of electrical equipment should be performed only by qualified service person- nel.
  • Page 9 TROUBLESHOOTING (cont.) PROBLEM Brew cycle will not start (cont) Brew cycle starts with brew lockout relay engaged. PROBABLE CAUSE 2. No power or incorrect voltage to the brewer (cont) 3. Water level below pump housing. (Water level in the hot water gauge glass should be approximately half full).

  • Page 10: On/Off Switch

    TROUBLESHOOTING (cont.) PROBLEM Tank not filling Water running out of the over- flow PROBABLE CAUSE 1.ON/OFF Switch (This switch must be in the "ON" position for the refill circuit to operate. 2. No water 3. Solenoid Valve 4. Probe 5. Liquid Level Board 1.Brewer not level 2.
  • Page 11 Inconsistent coffee yield Funnels overflow PROBABLE CAUSE 1. Limit Thermostat CAUTION - Do not eliminate or bypass limit thermostat. Use only Bunn-O-Matic replacement part #29329.1000 2. Control Thermostat 3. Tank Heater(s) 4. Contactor 1. Circuit Breaker 2. Tank Heater(s) 1.
  • Page 12 TROUBLESHOOTING (cont.) PROBLEM Funnels overflow (cont.) Coffee reservoir overflows Brewer is making unusal noises PROBABLE CAUSE 3. Pump - Flow Rate 4. Soft Water 1. Coffee reservoir not completely empty befor a brew cycle was started. 2. Timer 3. Pump - Flow Rate 1.

  • Page 13: Table Of Contents

    SERVICE This section provides procedures for testing and replacing various major components used in this brewer should service become necessary. Refer to Troubleshooting for assistance in determining the cause of any problem. WARNING - Inspection, testing, and repair of electri- cal equipment should be performed only by qualified service personnel.

  • Page 14: Circuit Breaker

    SERVICE (cont.) CIRCUIT BREAKER (120/208V and 120/240V Three Wire Models and 440V Four Wire Models) FIG. 2 CIRCUIT BREAKER Location: The circuit breaker is located on the right rear of the component bracket. Test Procedures: 1. Disconnect the brewer from the power source. 2.

  • Page 15: Contactor

    SERVICE (cont.) CONTACTOR FIG. 4 CONTACTOR Location: The contactor is located on the left front of the component bracket Test Procedures: 1. Disconnect the brewer from the power source. 2A. 120/208V, 120/240V, 380V THREE WIRE MODELS, 380V and 440V FOUR WIRE MODELS Disconnect the black wire from the contactor coil to the limit thermostat and black wire from the white wire on the main harness.
  • Page 16 SERVICE (cont.) CONTACTOR (cont.) 9. Check for continuity across the terminals on the left side of the contactor by manually closing the contacts. Continuity must not present when the contact is released. 10. Check for continuity across the terminals on the right side of the contactor by manually closing the contacts.Continuity must not be present when the contact is released.

  • Page 17: Control Thermostat

    SERVICE (cont.) CONTROL THERMOSTAT FIG. 6 CONTROL THERMOSTAT Location: The control thermostat is mounted on the right front of the component bracket. Test Procedures: 1. Disconnect the brewer from the power source. 2. Locate the thermostat and the voltage check points.

  • Page 18: Fuse And Fuse Holder

    SERVICE (cont.) FUSE AND FUSE HOLDER (208V, 240V, 230V Two Wire Models and 380V Three Wire Models) FIG.8 FUSE AND FUSE HILDER Location: The fuse and fuse holder are located on the right rear of the component bracket. Test Procedures: 1.

  • Page 19: Limit Thermostat

    SERVICE (cont.) LIMIT THERMOSTAT FIG. 10 LIMIT THERMOSTAT Location: The limit thermostat is located on the center front of the component bracket behind the timer mounting bracket. Test Procedures: 1. Disconnect the brewer from the power source. 2. Disconnect the black wires or the red wires from the limit thermostat.

  • Page 20: Liquid Level Board And Level Probe

    SERVICE (cont.) LIQUID LEVEL BOARD AND LEVEL PROBE FIG.12 LIQUID LEVEL BOARD AND LEVEL PROBE Location: The liquid level board is located on the left rear of the component bracket. The level probe is located on the right rear of the component bracket. Test Procedures: 1.
  • Page 21 SERVICE (cont.) LIQUID LEVEL BOARD AND LEVEL PROBE (cont.) 9. Reconnect the pink wire to terminal 4. 10. Remove the two #8-32 screws securing the level probe to the component bracket. 11. Gently pull the probe out of the component bracket and inspect for corrosion.

  • Page 22: On/Off Switch

    SERVICE (cont.) ON/OFF SWITCH FIG.14 ON/OFF SWITCH Location: The ON/OFF switch is located on the left side of the switch mounting bracket. The switch mounting bracket is mounted on the front of the component bracket. Test Procedures: 1. Disconnect the brewer from the power source. 2.

  • Page 23: Pump

    SERVICE (cont.) PUMP ASSEMBLY FIG.16 PUMP ASSEMBLY Location: The pump is located on the center rear of the component bracket. Test Procedures: 1. Disconnect the brewer from the power source. 2. Disconnect the black wire from the black lead on the pump and the white wire from the black lead on the pump.

  • Page 24: Relay

    SERVICE (cont.) RELAY (BREWERS W/BREW LOCKOUT) FIG.18 RELAY Location: The relay is located on the front part of the com- ponent bracket, mounted on the top of the timer bracket. Test Procedures: All Models Except 230V - CE Models 1. Disconnect the brewer from the power source. 2.
  • Page 25 SERVICE (cont.) RELAY (BREWERS W/BREW LOCKOUT) Removal and Replacement: 1. Disconnect the wires from the relay. 2. For 120/208V, 120/240V, 208V, 380V, 440V and 240V models prior to #U300004095 remove the #6-32 screw securing the relay to the relay mount- ing bracket.

  • Page 26: Selector Switch (Half Batch)

    SERVICE (cont.) SELECTOR SWITCH (HALF BATCH OPTION) FIG. 20 SELECTOR SWITCH (HALF BATCH) Location: The selector switch is located in the upper center of the switch mounting panel. Test Procedures: 1. Disconnect the brewer from the power source. 2. Disconnect the wires from the switch terminals. 3.

  • Page 27: Solenoid

    SERVICE (cont.) SOLENOID FIG. 22 SOLENOID Location: The solenoid is mounted on the upper left rear of the component bracket. Test Procedures: 1. Disconnect the dispenser from the power source. 2. A) For 120/208 volt and 120/240 volt three wire, single phase models, 380 volt three wire, three phase models and 380 volt, 440 volt four wire, three phase models, disconnect the black wire...
  • Page 28 SERVICE (cont.) SOLENOID 6. Remove the tank inlet tube grommet and dis- card. 7. Install new tank inlet tube grommet. 8. Install new solenoid assembly. 9. Install liquid level board, shield and secure solenoid assembly and shield to the component bracket with a #10-32 screw and flat washer..

  • Page 29: Start Switch (Brew)

    SERVICE (cont.) START SWITCH (BREW) FIG. 24 START SWITCH (BREW) Location: The brew start switch is located on the upper right side of the brewer component housing. Test Procedures: 1. Disconnect the brewer from the power source. 2. Remove the wires from the start switch termi- nals.

  • Page 30: Tank Heaters

    SERVICE (cont.) TANK HEATERS FIG. 26 TANK HEATER Location: The tank heaters are located on the right center and the left center of the component bracket. BLK to Contactor L1 (120/208V, 120/240 Three Wire Single Phase, 208V and 240V Two Wire, Single Phase) BLU to Main Harness (208V, 240V, 380V Three...

  • Page 31: Thermal Cut-Off

    SERVICE (cont.) THERMAL FUSES (230V-CE MODELS ONLY) FIG. 28 THERMAL FUSES Location: The thermal fuses are mounted on the tank heater terminals and the contactor terminals. Test Procedures: 1. Disconnect the brewer from the power source. 2. Disconnect the thermal fuse from the tank heater terminal and the contactor terminal.
  • Page 32 SERVICE (cont.) TIMER (Early Models)(cont.) 5. With a voltmeter, check the voltage across the sockets P1 and P2 (blue and white wires) of the female connector on the main harness when the "ON/OFF" switch is in the "ON" (upper) position and the start switch pressed.

  • Page 33: Digital Timer (Late Models)

    SERVICE (cont.) DIGITAL TIMER (Late Models) FIG. 32 DIGITAL TIMER Location: The timer is located on the front center of the component bracket. Test Procedure. NOTE: Do not remove or install wires while timer board is installed. Pressure applied to one side may cause damage to the board.
  • Page 34 SERVICE (cont.) DIGITAL TIMER (Late Models) NOTE: All volume settings must be done with the sprayhead installed. 1. Modifying brew volumes. To modify a brew vol- ume, first check that the SET/LOCK switch is in the “SET” position on the circuit board. To increase a brew volume, place the ON/OFF switch in the “ON”...

  • Page 35: Transformer

    SERVICE (cont.) TRANSFORMER (380V THREE WIRE MODELS ONLY) FIG. 34 TRANSFORMER Location: The transformer is located on the top rear of the timer mounting bracket. Test Procedures: 1. Disconnect the brewer from the power source. 2. Disconnect black wire and the red wire from the terminal block at the transformer.

  • Page 36: Master On/Off Switch (Late Models)

    SERVICE (cont.) MASTER ON/OFF SWITCH (Late Models) FIG. 36 MASTER ON/OFF SWITCH LOC. Location: The Master ON/OFF switch is located in the top hous- ing at the rear, FIG. 36. Test Procedure: Disconnect the brewer from the power source and remove the wires from all terminals of the Master ON/OFF switch.
  • Page 37 MAIN ON/OFF SWITCH (Late Models only) 120/208 VOLTS AC 120/240 VOLTS AC 3 WIRE + GND SINGLE PHASE 10492.0000E 03/07 © 1990 BUNN-O-MATIC CORPORATION Page 37 10060 011708...
  • Page 38 Page 38 10060 080900...
  • Page 39 SCHEMATIC WIRING DIAGRAM U3A & U38A (BREWERS PRIOR TO U300004095) Page 39 10060 080900...
  • Page 40 SCHEMATIC WIRING DIAGRAM U3A - CE (BREWERS S/N U300004095 - UP) Page 40 10060 080900...
  • Page 41 SCHEMATIC WIRING DIAGRAM U3833 Page 41 10060 080900...

  • Page 42: Wiring Diagrams

    SCHEMATIC WIRING DIGRAM U3833 Page 42 10060 080900...

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