Bunn Ultra NX Service & Repair Manual
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Bunn Ultra NX Service & Repair Manual

Frozen beverage dispensers
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Ultra
NX
®
Frozen Beverage Dispensers
SERVICE & REPAIR MANUAL
Bunn-O-Matic Corporation
Post Office Box 3227, Springfield, Illinois 62708-3227
Phone (217) 529-6601 | Fax (217) 529-6644
www.bunn.com
58041.0000 B 08/22 © 2022 Bunn-O-Matic Corporation

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  • Page 1 Ultra ® Frozen Beverage Dispensers SERVICE & REPAIR MANUAL Bunn-O-Matic Corporation Post Office Box 3227, Springfield, Illinois 62708-3227 Phone (217) 529-6601 | Fax (217) 529-6644 www.bunn.com 58041.0000 B 08/22 © 2022 Bunn-O-Matic Corporation...
  • Page 2 LIMITED, AT BUNN’S 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: Table Of Contents

    CONTENTS Equipment Notices & Safeguards ................4 Operating Controls ...................... 5 Software Program Informational Screens ..............7 Product Instructions ..................... 8 Brix Pump/Autofill Set-Up Diagram ................9 CFV/Autofill Set-Up Diagram ..................10 Preventive Maintenance .................... 11 Troubleshooting ......................15 Fault Messages ......................24 Equipment Service Panels ..................

  • Page 4: Equipment Notices & Safeguards

    • Counter or table capable of supporting at least 180 lbs. • Indoor use only. • Ultra NX must have at least six inches of space behind it. The space is needed for airflow, air filter removal, and cleaning. • A clearance of at approximately six inches is recommended between the dispenser sides and the wall or another appliance.

  • Page 5: Operating Controls

    OPERATING CONTROLS There are five of these switches that will be used for the operation of the dispenser. 1. Switch - Upper left corner of the control pad: This switch is the ON/OFF toggle switch which powers up the dispenser and the LCD display. When ON the Date and Time toggle back and forth continuously except during programming.
  • Page 6 OPERATING CONTROLS Using the menu-driven display on the front of the dispenser, the operator has the ability to alter or modify various parameters such as beverage consistency and set day/night “ON/OFF” times. The operator is also prompted to check a variety of periodic service functions or even a step-by-step cleaning routine. There is also the opportunity to return all changes back to factory default settings.

  • Page 7: Software Program Informational Screens

    SOFTWARE PROGRAM INFORMATIONAL SCREENS Display Temp and Torque Screens The TEMP & TORQUE mode is typically used for seeing real time component On/Off operation, product thickness, cooling drum and hot gas temperature for troubleshooting purposes. Press and hold the left and right hidden buttons for 5 seconds to display the TEMP & TORQUE screen. The temperature of each cooling drum and the hot gas temperature will toggle back and forth.

  • Page 8: Product Instructions

    Helpful information • BUNN recommends that the product in the dispenser be thawed each day, usually overnight. The ice granules get too large and a consistent product is difficult to maintain if left frozen for an extended period of time.

  • Page 9: Brix Pump/Autofill Set-Up Diagram

    BRIX PUMP (AUTOFILL) SETUP DIAGRAM 1. Connect the water line to the water fitting in the ULTRA hopper. 2. Connect the concentrate line from the syrup pump to the product fitting in the ULTRA hopper. PRESSURE REQUIREMENTS*: WATER = 0.207 MPa - 0.552 MPa (30-80 PSI) ULTRA is equipped with a 3/8 inch Barbed fitting.

  • Page 10: Cfv/Autofill Set-Up Diagram

    CFV (AUTOFILL) SETUP DIAGRAM 1. Connect the water line to the water fitting in the ULTRA motor cover. 2. Connect the concentrate line from the syrup pump to the product fitting in the ULTRA motor cover. PRESSURE REQUIREMENTS**: WATER = 0.207 MPa - 0.552 MPa (30-80 PSI) CONCENTRATE = 0.275 MPa - 0.552 MPa (40-80 PSI) ULTRA is equipped with a 3/8 inch Barbed fitting.

  • Page 11: Preventive Maintenance

    Corporation recommends that preventive maintenance be performed at regular intervals. Maintenance should be performed by a qualified service technician. For Technical Service, contact Bunn-O-Matic Corporation at 1-800-286-6070 NOTE: Replacement parts or service caused by failure to perform required maintenance is not covered by warranty.
  • Page 12 Installation & Operating manual. A copy can be down- loaded on BUNN’s website. 7. Remove the cooling drum seal 8. Use a pointed tool to remove 9. Use the provided tool to...
  • Page 13 PREVENTIVE MAINTENANCE ULTRA PM Instructions 11. Replace the auger shaft 10. Remove the cooling drum 12. Remove dispense handles. seals. P/N: 26780.0000. Apply seal from the rear of the drum. Spread the left side of the lubricant (M2550.0000) to the handle first, then the other Replace the seal with P/N: auger shaft seals and install...
  • Page 14 PREVENTIVE MAINTENANCE ULTRA PM Instructions COOLING DRUM ALIGNMENT The “A” shaped Cooling Drum Shipping Supports, removed during Initial Setup, should be kept and used as tools to reset the alignment of the Cooling Drums if ever required. Symptoms Squeaky Operation, hopper lifts or won’t seat properly, hopper is pushed to one side or the other. Ledge Boss 2.

  • Page 15: Troubleshooting

    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. Fault messages are now incorporated within the software and may appear on the User display.
  • Page 16 TROUBLESHOOTING Chills but won’t freeze Dispenser in “DAY” mode? Set into “DAY” mode Dispenser in “ICE” mode? Verify augers Set into are turned on “ICE” mode Is display showing UPPER CASE “ICE” mode? Is Brix Is Thickness level high? screen set low? Is Filter dirty? Inspect auger drive shafts for weak torsion springs or...
  • Page 17 TROUBLESHOOTING No cooling at all Is ICE/CHILL set to off? Set into “ICE” or “CHILL” mode Is compressor running? Is filter Is Dispenser on dirty? an extension cord? Plug directly into outlet Is there correct Check fan voltage at outlet? Call a licensed Have a certified electrician...
  • Page 18 TROUBLESHOOTING Freezes, but not thick enough Ambient Adjust thickness Brix ratio Too much temperature screen higher too high alcohol in too hot product Check for slightly Recommended Adjust bent auger shaft for indoor product pins and/or weak use only torsion springs. Check for dirty or worn seals and bushings.
  • Page 19 TROUBLESHOOTING Noise Auger jumping Check fan Lower brix ratio Drum alignment Check auger shaft bushings Auger won’t turn Do they turn during “AUGER MOTOR TEST” mode? One direction, Auger motor/capacitor but not the other checks Check membrane switch Replace control board continued >...
  • Page 20 TROUBLESHOOTING Torque Sensor Error TORQUE SENSOR TORQUE SENSOR ERROR TORQUE SENSOR OPEN SHORTED Right side Left side Right side Left side Are augers Sensor unplugged or turning? break in wiring Go to motor troubleshooting Are augers shaft pins Check sensor damaged or missing? circuit Replace as necessary...
  • Page 21 TROUBLESHOOTING Temperature Sensor Error TEMPERATURE SENSOR SHORTED TEMPERATURE SENSOR OPEN Right side Left side Left side Right side Product not covering Check wiring harness between back end of drum. thermistor and control board Drum temperature falls below 9° F. Replenish product Thermistor unplugged or break in wiring Check thermistor...
  • Page 22 TROUBLESHOOTING Clean Filter Messages “MONTHLY FILTER “FILTER NEEDS CLEAN REQUIRED” CLEANING” Hot gas thermistor Monthly reminder sensing over 205° F Dirty filter; air flow blockage; Clean filter wrong refrigerant or over charged Hold LEFT DOT button (under display) for 3 seconds to reset. continued >...
  • Page 23 TROUBLESHOOTING A common problem occurs when the proper preventive maintenance procedures are not followed. Failure to perform these procedures may result in damaged equipment and may not be covered by warranty. Fault Message: “CHECK LEFT SIDE” “PRODUCT MIX” “OR DRIVE SYSTEM” “CHECK RIGHT SIDE”...

  • Page 24: Fault Messages

    FAULT MESSAGES User Panel The following are fault messages that “may” appear on the user LCD display. The issue will need to be resolved before the message goes away. The resolution to clear the message / condition are: a) Instructional Information on Screen - Press Button b) Self Clears If Condition Goes Away and/or for Over 2 Minutes c) Self Clears If Condition Goes Away or User Overrides or Next Defrost Cycle is Started d) Self Clears When Next Defrost Cycle is Started...
  • Page 25 FAULT MESSAGES User Panel CHECK PRODUCT MIX OR DRIVE SYSTEM Trip Condition: This message appears when the left or right torque sensor detects a fault. This can be due to a pin problem or frozen auger. Probable Cause: Inconsistent product mix ratio (very low brix percentage), residue build-up or too much Krytox grease on auger motor pin, defective position sensor (torque) board.
  • Page 26 FAULT MESSAGES User Panel DEFROST INCOMPLETE Trip Condition: This message appears if the left or right Barrel Defrost did not complete successfully (pos- sibly either cancelled or defrost time frame too short). Probable Cause: Given the condition per location, the “Defrost” time set too short. Operator should enter software menu and increase the Defrost time.

  • Page 27: Equipment Service Panels

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

  • Page 28: Service - Front Panel Components

    SERVICE - FRONT PANEL COMPONENTS Control Board and Auto-Fill Board If voltage is not present as described, refer to the Wiring Diagram and check the dispenser universal power supply and wiring harness. Part Removal and Replacement: 1. Disconnect the dispenser from the power source.

  • Page 29: Membrane Switch

    SERVICE - FRONT PANEL COMPONENTS Membrane Switch If the input is not recognized by pressing a switch on the membrane pad, replace membrane switch. Membrane Switch Diagram: NOTE: #7 - Common to all the buttons. #7 - #1 (shield) no continuity #7 - #2 (Left Auger) #7 - #3 (I/O) #7 - #4 (not used)
  • Page 30 SERVICE - FRONT PANEL COMPONENTS Membrane Switch FIG. 3 MEMBRANE SWITCH Part Removal and Replacement: 1. Disconnect the dispenser from the power source. 2. Remove right and left side panels. 3. Remove front panel and disconnect membrane switch ribbon from wiring harness. 4.

  • Page 31: Service - Hopper Lid Assembly

    SERVICE - HOPPER LID ASSEMBLY LED/CBA and MAG Cord Assembly 7. Press the “Left Dot” switch to answer “ON”. Left Lid Light will illuminate. NOTE: Power output to the Left or Right Lid Light is 24VDC. 8. Press the “Center Dot” switch to advance onto “Right Lid Light”...

  • Page 32: Service - Rear Cover Components

    SERVICE - REAR COVER COMPONENTS MAG Contact Assembly 4. Lift Mag Contact Assembly from the cooling drum mount hole. 5. Replace Mag Contact Assembly into cooling drum mount hole and secure with nut. 6. Reconnect Mag Contact 2-pin connector to the machine wiring harness connector.

  • Page 33: Left & Right Auger Motor

    SERVICE - REAR COVER COMPONENTS Left and Right Auger Motors 4. Press the “Right Dot” switch to answer “Yes”. 5. Press the “Center Dot” switch to scroll through the menus until “Test Augers?” menu is displayed. 6. Press the “Right Dot” switch to answer “Yes” to enter “Left Auger Test”...
  • Page 34 NOTE: BUNN recommends the flats on the front of the shaft that engage the auger nose are set to a horizontal position, the pins will not be in the torque sensor board before removal of the motor assembly.

  • Page 35: Left And Right Auger Motor Capacitor

    SERVICE - REAR COVER COMPONENTS Left and Right Auger Motor Capacitor Auger Motor Capacitor Ratings: 120V Models: Capacitance - 4.0μF-5%/+10%, VOLTAGE - 250 VAC 50/60 Hz. 240V Models: Capacitance - 1.25μF±5%, VOLTAGE - 500 VAC 50/60 Hz If it is outside the allowable capacitance range, then the capacitor needs to be replaced.

  • Page 36: Left & Right Torque Sensor Board

    SERVICE - REAR COVER COMPONENTS Left and Right Torque Sensor Board 1. Left Signal (WHI/GRY) 1. Right Signal (WHI/GRN) 2. (+) 5vdc (BLU) 3. (-) common (WHI/BLK) L.E.D. PHOTO TRANSISTOR FIG. 13 CBA POSITION/TORQUE SENSOR FIG. 14 TORQUE SENSOR BOARD TERMINALS Location: The torque sensor circuit board is located on the...
  • Page 37 SERVICE - REAR COVER COMPONENTS Torque Sensor Circuit Board 11. Reinstall the 3 nuts that secure the motor mounting bracket to the chassis. 12. Reconnect the auger motor 4-pin connector to the machine wiring harness. FIG. 15 CBA POSITION/TORQUE SENSOR Part Removal and Replacement: 1.

  • Page 38: Left & Right Ptc Heater

    1. Remove 4 screws securing rear cover. Defrost Heater/PTC Ratings 2. Grab cover and pull away from machine. Ultra NX 120V Models: Heater Assembly, PTC 120V ULTRA NX Test Procedures: RESISTANCE: 350-450 OHMS NOTE: Going to check cooling drum defrost heater...
  • Page 39 SERVICE - REAR COVER COMPONENTS Left and Right PTC Heater 9. Facing the rear cooling drum, position the surface with the heat sink compound on the defrost heater assembly to the left and begin pushing the heater all the way into the housing until it stops.

  • Page 40: Left & Right Cooling Drum Temperature Sensor

    SERVICE - REAR COVER COMPONENTS Left and Right Cooling Drum Temperature Sensor Resistance Check 2. Disconnect the plug on thermistor leads and check resistance as indicated below. The indication must be within range of known temperature: a) 1,473 - 1,614 ohms @ 32° F (Water with Ice) b) 394 - 454 ohms @ 71°...

  • Page 41: Cf Cfive Solenoid Valves - Cfv/Autofill

    4. Grab cover with water and syrup line still connected to the inlet barb fitting and gently pull cover away from machine. Electrical Rating: Ultra NX 120V Models: Test Procedure: CFV CFIVE Solenoid Valve: 24VDC NOTE: The Dual Inlet Hopper Fitting is removed...
  • Page 42 SERVICE - REAR COVER COMPONENTS CF CFIVE Solenoid Valves - CFV/Autofill Outlet Inlet FIG. 21 CF CFIVE VALVE Part Removal and Replacement: NOTE: Removal and replacement instruction below can be used for the water or syrup CF CFIVE solenoid valve. 1.

  • Page 43: Left & Right Pressure Switch - Cfv/Autofill

    SERVICE - REAR COVER COMPONENTS Left and Right Pressure Switch - CFV/Autofill If the supply CO and pressure setting is adequat and the status reads “Good” on left and right side, but no operation of the water and syrup valve to delver product, check and make sure the “Auger Refill On”...

  • Page 44: Cf Cfive Solenoid Valves - Laf/Autofill

    2. Lift hopper cover to remove dual inlet fitting Electrical Rating: from hopper. 3. Remove 4 screws securing rear cover. Ultra NX 120V Models: 4. Grab cover with water line still connected to the CFV CFIVE Solenoid Valve: 24VDC inlet barb fitting and gently pull cover away from Ultra NX 200-240V Models: machine.
  • Page 45 SERVICE - REAR COVER COMPONENTS CF CFIVE Solenoid Valves - LAF/Autofill Outlet Inlet FIG. 23 CF CFIVE VALVE Part Removal and Replacement: 1. Disconnect power supply from the machine. 2. Shut off the main water to the external Brix Proportional Pump 3.

  • Page 46: Left & Right Refrigerant Solenoids

    R-290 refrigeration system. R290 Solenoid Valve Ratings: FIG. 24 R290 REFRIGERANT SOLENOIDS Ultra NX 120V Models: Location: Solenoid Valve: 120VAC/60HZ-110VAC/50HZ The refrigerant solenoids are mounted on a bracket Ultra NX 200-240V Models: that is attached in the rear between the auger motors behind the Auger Motor cover.

  • Page 47: Left & Right Auger Shaft Assembly

    SERVICE - REAR COVER COMPONENTS Left and Right Auger Shaft Assembly 4. Exit software program. 5. Press and hold “Left & Right Dot” simultaneously for 5 seconds to enter the “Display Temp & Torque” screen. See FIG. A. NOTE: The informational screens will automatically toggle back and forth.
  • Page 48 SERVICE - REAR COVER COMPONENTS Left and Right Auger Shaft Assembly being careful that the motor .188 pin clears the board sensors. Set motor aside. 6. Rotate shaft so the shaft .188 pin clears the DISPLAY sensor board. Next, pull the auger shaft backward TEMP &...

  • Page 49: Service - Left Side Panel Components

    SERVICE - LEFT SIDE PANEL COMPONENTS Refrigeration Hot Gas Temperature Sensor Resistance Check 3. Disconnect the plug on the hot gas sensor leads from the connector on the main harness. 4. Connect an ohmmeter across the two leads of the hot gas sensor; The indication must be within range of known temperature: a) 7,216 - 7,574 ohms @ 32°...

  • Page 50: Condenser Fan Assembly

    The fan is located inside the dispenser chassis just in front of the condenser. Condenser Fan Specifications: Left Panel Removal: Ultra NX 120V Models: 1. Loosen 2 left side panel screws on the VOLTAGE: 115VAC/50-60HZ underside of the machine. MAX INPUT POWER: 31W 2.

  • Page 51: Service - Right Side Panel Components

    SERVICE - RIGHT SIDE PANEL COMPONENTS Compressor Relay No 24VDC across relay coil terminals, replace control board. Yes 24VDC across relay coil terminals, continue with testing steps. 9. Disconnect dispenser power to remove wires from the relay normally open contact terminals. 10.

  • Page 52: Power Supply

    Autofill models. panel and mounted to the side frame above the 9. Install power supply with screws back through capacitors. Power supply could be BUNN Part the machine mounting key holes and tighten. Number 33363.0013, 33363.0014 or 33363.0019. Right Panel Removal: 1.
  • Page 53 4 - NC = No Connection bottom outward to remove panel. 5 - V3 = 12VDC - Red wire power to IOT 6 - +V2 = 24VDC to Ultra NX – White with Test Procedures: blue stripe NOTE: The power supply accepts incoming 7 - COM = Common/ground –...

  • Page 54: R-290 Compressor Hazard Classification & Safeguards

    • Trained service personnel with the knowledge of servicing and troubleshooting R-290 refrigeration systems or related components should be used. • All components used in Ultra NX are rated for refrigerant R-290 application. • Always be alert of smell and sounds (arching, popping and humming) coming from the compressor.

  • Page 55: R-290 Compressor

    SERVICE - RIGHT SIDE PANEL COMPONENTS R-290 Compressor 5. Connect one lead of the megger to the copper suction line or housing. Connect the other lead to one of the compressor terminal pins (winding). 6. Repeat the procedure for the two remaining terminal pins.
  • Page 56 SERVICE - RIGHT SIDE PANEL COMPONENTS R-290 Compressor 5. Next, technician will remove the four .25-20 keps nuts and washers securing the compressor to the chassis. Set nuts and washers aside for reassembly. Common 6. From the left side of the dispenser, lift the compressor assembly over the four studs in the chassis and remove compressor.

  • Page 57: R-290 Compressor Start & Run Capacitor

    Start Capacitor Rating: CAUTION: Start Capacitors having a bleed resistor across the terminals will bleed off residual voltage Ultra NX 120V Models: in a start capacitor after it has been removed from RATING: 340-408 MFD 165 V 50/60HZ a motor circuit after start up. Not all Start or Run Ultra NX 200-240V Models: capacitors use bleed resistors.
  • Page 58 Run Capacitor Rating: underside of the machine. 2. Grab and lower the right panel while pulling the Ultra NX 120V Models: bottom outward to remove panel. RATING: 30 ±5% MFD 420 VAC 50/60HZ 3. Front panel will need to be removed to access...
  • Page 59 SERVICE - RIGHT SIDE PANEL COMPONENTS Start and Run Capacitor FIG. 44 START & RUN CAPACITOR WARNING: Part Removal & Replacement: Follow instruction outlined under Start and Run Capacitor Test Procedure to ensure the capacitor is completely discharged before removal and replacement of capacitor.

  • Page 60: R-290 Compressor Start Relay

    1 and 2 on the start relay. FIG. 45 START RELAY Start Relay Rating: Location: Ultra NX 120V Models: The start relay is located right side, up front below the capacitors. RELAY, NEX4170UA 115-127V 60 HZ Ultra NX 200-240V Models:...

  • Page 61: R290 Compressor Relay, Start & Run Wiring And Coolant Diagram

    SERVICE - COMPRESSOR WIRING DIAGRAM Compressor R-290: Wiring Diagram for Capacitors and Start Relay...
  • Page 62 R-290 COOLANT DIAGRAM...

  • Page 63: Control Board Triac Diagram And Control Board Input & Output Chart

    CONTROL BOARD TRIAC DIAGRAM LIQUID AUTO-FILL BOARD Relay 1 Relay 2 MAIN CONTROL BOARD TRIAC DESCRIPTION CONNECTOR TERMINAL Right Refrigerant Solenoid J15-12 Left Refrigerant Solenoid J15-11 J15-10 Left Auger Motor J15-2 Reverse & J15-3 Forward - Relay 1 Right Auger Motor J15-7 Reverse &...
  • Page 64 CONTROL BOARD INPUT AND OUTPUT CHART J12-2pin Connector -Power Supply Input 24VDC J14-14pin Connector Main Harness - Low Voltage J15-12pin Connector for Main Harness - Line Voltage CONNECTOR & WIRE COLOR INPUT/OUTPUT DESCRIPTION VOLTAGE PIN NUMBER J12-1 WHT/RED Input/+ Control Board 24VDC J12-2 WHT/BLK...
  • Page 65 INPUT AND OUTPUT CHART J7-12pin Connector - Membrane Switch J3-4pin BUNNlink CONNECTOR & WIRE COLOR INPUT/OUTPUT DESCRIPTION VOLTAGE PIN NUMBER J7-1 Input Ground J7-2 Input Left Auger 5VDC J7-3 Input 5VDC J7-4 Input Not Used 5VDC J7-5 Input Left Ice/Chill/Off 5VDC J7-6 Input...

  • Page 66: Ultra ® Nx Wiring Schematic

    120 VOLTS AC TORQUE TORQUE LEFT RIGHT SENSOR SENSOR 60 HZ 220-240 VOLTS AC VIOLET Left Hopper Lights 50 HZ *Substitute Wire Color WHI/VIOLET RightHopper Lights 2 WIRE 57667.0000 SINGLE PHASE Compressor Relay 32082.0003 A 08/22 © 2015 BUNN-O-MATIC CORPORATION...

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