Bunn Coffee Maker DUAL TF DBC Service Manual

BrewWISE

DBC

BREWERS

WITH SMART FUNNEL

SERVICE & REPAIR MANUAL

BUNN-O-MATIC CORPORATION

POST OFFICE BOX 3227

SPRINGFIELD, ILLINOIS 62708-3227

PHONE: (217) 529-6601 FAX: (217) 529-6644

BUNN-O-MATIC COMMERCIAL PRODUCT WARRANTY

Bunn-O-Matic Corp. (“BUNN”) warrants equipment manufactured by it as follows:

1) All equipment other than as speciﬁed below: 2 years parts and 1 year labor.

2) Electronic circuit and/or control boards: parts and labor for 3 years.

3) Compressors on refrigeration equipment: 5 years parts and 1 year labor.

4) Grinding burrs on coffee grinding equipment to grind coffee to meet original factory screen sieve analysis: parts and labor for 3 years or 30,000 pounds of coffee, whichever comes ﬁrst.

These warranty periods run from the date of installation BUNN warrants that the equipment manufactured by it will be commercially free of defects in material and workmanship existing at the time of manufacture and appearing within the applicable warranty period. This warranty does not apply to any equipment, component or part that was not manufactured by BUNN or that, in BUNN’s judgment, has been affected by misuse, neglect, alteration, improper installation or operation, improper maintenance or repair, damage or casualty. This warranty is conditioned on the Buyer 1) giving BUNN prompt notice of any claim to be made under this warranty by telephone at (217) 529-6601 or by writing to Post Ofﬁce Box 3227, Springﬁeld, Illinois 62708-3227; 2) if requested by BUNN, shipping the defective equipment prepaid to an authorized BUNN service location; and 3) receiving prior authorization from BUNN that the defective equipment is under warranty.

THE FOREGOING WARRANTY IS EXCLUSIVE AND IS IN LIEU OF ANY OTHER WARRANTY, WRITTEN OR ORAL, EXPRESS OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, ANY IMPLIED WARRANTY OF EITHER MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. The agents, dealers or employees of BUNN

are not authorized to make modiﬁcations to this warranty or to make additional warranties that are binding on BUNN. Accordingly, statements by such individuals, whether oral or written, do not constitute warranties and should not be relied upon.

If BUNN determines in its sole discretion that the equipment does not conform to the warranty, BUNN, at its exclusive option while the equipment is under warranty, shall either 1) provide at no charge replacement parts and/or labor (during the applicable parts and labor warranty periods speciﬁed above) to repair the defective components, provided that this repair is done by a BUNN Authorized Service Representative; or 2) shall replace the equipment or refund the purchase price for the equipment.

THE BUYER’S REMEDY AGAINST BUNN FOR THE BREACH OF ANY OBLIGATION ARISING OUT OF THE SALE OF THIS EQUIPMENT, WHETHER DERIVED FROM WARRANTY OR OTHERWISE, SHALL BE 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.

AutoPOD, AXIOM, BrewLOGIC, BrewMETER, Brew Better Not Bitter, BrewWISE, BrewWIZARD, BUNN Espress, BUNN Family Gourmet, BUNN Gourmet, BUNN Pour-O-Matic, BUNN, BUNN with the stylized red line, BUNNlink, Bunn-OMatic, Bunn-O-Matic, BUNNserve, BUNNSERVE with the stylized wrench design, Cool Froth, DBC, Dr. Brew stylized Dr. design, Dual, Easy Pour, EasyClear, EasyGard, FlavorGard, Gourmet Ice, Gourmet Juice, High Intensity, iMIX, Infusion Series, Intellisteam, My Café, PowerLogic, Quality Beverage Equipment Worldwide, Safety-Fresh, savemycoffee.com, Scale-Pro, Silver Series, Single, Smart Funnel, Smart Hopper, SmartWAVE, Soft Heat, SplashGard, The Mark of Quality in Beverage Equipment Worldwide, ThermoFresh, 392, A Partner You Can Count On, Air Brew, Air Infusion, Beverage Bar Creator, Beverage Proﬁt Calculator, Brew better, not bitter., BUNNSource, Coffee At Its Best, Cyclonic Heating System, Digital Brewer Control, Nothing Brews Like a BUNN, Pouring Proﬁts, Respect Earth, Respect Earth with the stylized leaf and coffee cherry design, Signature Series, Tea At Its Best, Phase Brew, The Horizontal Red Line, Titan, trifecta, Ultra, Velocity Brew are either trademarks or registered trademarks of Bunn-O-Matic Corporation.

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TABLE OF CONTENTS

Warranty .....................................................................................................................................2

Table of Contents ........................................................................................................................3

Troubleshooting ..........................................................................................................................4

Service Tools .............................................................................................................................15

Component Access ...................................................................................................................19

Control Board ......................................................................................................................19

Membrane Switch ................................................................................................................20

Dispense and Bypass Valves................................................................................................21

Reﬁll Valves .........................................................................................................................22

Tank Heaters ........................................................................................................................24

Temperature Probe ..............................................................................................................25

Limit Thermostats ...............................................................................................................25

Warmer Elements ................................................................................................................26

Master Power Switch ...........................................................................................................26

SH Server Timer ..................................................................................................................27

Schematic (Wiring Diagram) .....................................................................................................28

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41746 040210

TROUBLESHOOTING

OVERFLOW CUP

FULL. EMPTY CUP

SERVER NOT

IN PLACE

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 qualied

service personnel.

 • Allelectroniccomponentshave120-240voltacandlowvoltagedcpotentialontheirterminals.

Shorting of terminals or the application of external voltages may result in board failure.

 • Intermittentoperationofelectroniccircuitboardsisunlikely.Boardfailurewillnormallybeper-

manent. If an intermittent condition is encountered, the cause will likely be a switch contact or a loose connection at a terminal or crimp.

 • Solenoidremovalrequiresinterruptingthewatersupplytothevalve.Damagemayresultifsole-

noids are energized for more than ten minutes without a supply of water.

 • Theuseoftwowrenchesisrecommendedwheneverplumbingttingsaretightenedorloosened.

This will help avoid twists and kinks in the tubing.

 • Makecertainthatallplumbingconnectionsaresealedandelectricalconnectionstightandiso-

lated.

 • Thisbrewerisheatedatalltimes.Keepawayfromcombustibles.

WARNING

 • Exerciseextremecautionwhenservicingelectricalequipment.  • Disconnectthebrewerfromthepowersourcewhenservicing,exceptwhenelectricaltestsare

speciﬁed.

 • Followrecommendedserviceprocedures.  • Replaceallprotectiveshieldsorsafetynotices.

Screen Displayed

(SH Models only)

Possible Cause

1. Overﬂow cup is full of water. This could be caused by boiling. Refer to SET TEMP and REFILL sections in Programming Manual.

1. Soft Heat Server not correctly positioned on base.

2. Not using a Soft Heat Server, and the SERVER DETECT function is activated (on).

Troubleshooting Procedures

Empty cup. Correct cause and retry.

Position the server so that the connector pins on the server make contact with connector on the brewer.

Disable the SERVER DETECT function.

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41746 112008

TROUBLESHOOTING (cont.)

NO FUNNEL

PRESENT

TEMPERATURE

TOO LOW

CHECK FUNNEL

FOR FRESH COFFEE

PRESS BREW

TO BREW ANYWAY

TO CANCEL

PRESS ON/OFF

TO FINISH:

PRESS BREW

BREW STOPPED!

FUNNEL REMOVED?

Screen Displayed

Possible Cause Troubleshooting Procedures

1. SMART FUNNEL not fully inserted into the funnel rails.

2. Not using a SMART FUNNEL, and the FUNNEL DETECT function is activated (on).

1. Water temperature in the tank does not meet the SET READY

TEMPERATURE.

1. Brew funnel was not removed after the previous brew cycle was ﬁnished.

Position the funnel so that the sensor is directly beneath the sensor coil on the brewer.

Disable the FUNNEL DETECT function.

(a) Wait for the brewer to heat to the proper temperature.

(b) Disable the BREW LOCKOUT function.

Remove funnel, check contents, and insert back into the funnel rails.

1. Brew funnel was moved out of position after the brew cycle was started.

Press BREW to start a brew cycle without removing the funnel.

To resume brewing, correctly position the funnel and press BREW again. The brew cycle will resume from the point it was interrupted.

Press ON/OFF to terminate the cycle.

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41746 112008

TROUBLESHOOTING (cont.)

TO CANCEL

PRESS ON/OFF

TO FINISH:

PRESS BREW

BREW STOPPED!

SERVER REMOVED?

TO CANCEL

PRESS ON/OFF

TO FINISH:

PRESS BREW

BREW STOPPED!

IS SWITCH OFF?

CHECK HEATING

CIRCUIT

HEATING TIME

TOO LONG

Screen Displayed

1. Soft Heat Server was moved out of position after the brew cycle was started.

1. ON/OFF switch was pressed after the brew cycle was started.

Troubleshooting ProceduresPossible Cause

To resume brewing, correctly position the Soft Heat Server and press BREW again. The brew cycle resumes from the point it was interrupted.

Press ON/OFF to terminate the brew cycle.

To resume brewing, press BREW again. The brew cycle resumes form the point it was interrupted.

1. Tank Heater failure

2. Triac Failure

3. Control Board/Thermistor failure

Press ON/OFF to terminate the brew cycle.

Service Required. See TANK HEAT-

ERS.

Service Required. See

Service Required. See CONTROL

BOARD

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41746 112008

TROUBLESHOOTING (cont.)

CHECK WATER

SUPPLY

FILL TIME TOO

LONG

CHECK FOR BAD

CONNECTIONS

TEMP SENSOR

OUT OF RANGE

CHECK WIRE FOR

SHORTS

TEMP SENSOR

OUT OF RANGE

Screen Displayed

1. Water shut off to brewer

2. Inlet Solenoid Valve failure

3. Control Board Failure

1. Temperature Sensor Probe wire(s) broken or not making connection.

Troubleshooting ProceduresPossible Cause

Check water supply shut-off

Service required. See REFILL VALVE.

Service required. See CONTROL BOARD.

Check wire and connection of both black and white wires of temperature probe.

1. Temperature Sensor Probe wire(s) shorted to housing, or to each other.

Check to conﬁrm that wire(s) are not pinched between two surfaces or connected to each other.

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41746 112008

TROUBLESHOOTING (cont.)

Problem

Equipment will not operate.

Brew cycle will not start.

Possible Cause

1. No power or incorrect voltage.

1. No water

2. ON/OFF switch

3. Brew switch

4. Brew Valve

Troubleshooting Procedure

Measure the voltage at the terminal block and conﬁrm that it matches the voltage speciﬁed on the brewer data plate within +/- 10%.

Check plumbing and shut-off valves

Test the ON/OFF switch. Refer to the switch test procedures in SERVICE TOOLS section.

Test the BREW switch. Refer to the switch test procedures in SERVICE TOOLS section.

Test the Brew valve. Refer to Testing

Individual Components in SERVICE TOOLS section.

Automatic reﬁll will not operate or display shows FILL TIME TOO LONG

5. Electronic Control Board

1. No water

2. Water strainer/ﬂow control (.750 GPM)

Substitute a control board known to be in good working order.

Check plumbing and shut-off valves.

(A) Direction of ﬂow arrow must be pointing towards direction of water ﬂow.

(B) Remove the strainer/ﬂow control and check for obstructions. Clear or replace.

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41746 112008

TROUBLESHOOTING (cont.)

Problem

Automatic reﬁll will not operate or

display shows FILL TIME TOO LONG

(cont.)

Possible Cause

3. Reﬁll Probe or Sensitivity Setting

Troubleshooting Procedure

Check the sensitivity setting. Refer to Reﬁll function. If the left three digit number is less than the right number, the machine “thinks” it is full and the reﬁll valve should be off. If the left number is larger than the right, then the reﬁll valve will automatically be turned on to ﬁll the tank. The right number is the threshold setting and can be adjusted to compensate for extreme water conditions: very pure, low conductance water requires a higher setting, while high mineral content, high conductance water requires a lower setting. Note that the left number changes from a high value when water is NOT touching the reﬁll probe to a low value when water IS touching the probe. For best operation, the right number should be set to a value midway between these low and high numbers. Before changing the setting, conﬁrm that the reﬁll probe is free of scale buildup and the connection to it is secure.

Water ﬂows into tank continuously

with power removed from brewer.

4. Reﬁll Valve

5. Overﬂow Protection Switch

6. Electronic Control Board

1. Reﬁll valve

Page 9

Test the Reﬁll valve. Refer to Testing Individual Components.

When this condition occurs, the brewer will display OVERFLOW CUP FULL. EMPTY CUP. The reason for overﬁlling could be a defective reﬁll valve, an incorrect sensitivity setting, (see above) or boiling.

Substitute a control board known to be in good working order.

Foreign material lodged in valve, holding it in open state.

41746 112008

TROUBLESHOOTING (cont.)

Power

Water ﬂows into tank continuously with power applied to brewer.

Possible Cause

1. Reﬁll Probe or Sensitivity Setting

Troubleshooting Procedures

Water will not heat or display shows HEATING TIME TOO LONG

2. Electronic Control Board

1. Limit Thermostat

CAUTION - Do not eliminate or bypass limit thermostat. Use only replacement part #23717.0003.

2. Tank Heaters

Page 10

Substitute a control board known to be in good working order.

Remove power from the brewer. Press reset button on limit thermostat. Then check for continuity through it.

Remove power from the brewer. Check for continuity through the tank heaters.

41746 112008

TROUBLESHOOTING (cont.)

Problem

Water will not heat or display shows

HEATING TIME TOO LONG (cont.)

Possible Cause

3. Triac

4. Electronic Control Board

Troubleshooting Procedures

Remove power from the brewer. Connect a voltmeter across one of the tank heaters. Reapply power to the brewer and refer to Testing Individual Components. If the full supply voltage is measured when the tank heater is turned on, and zero voltage is measured with the triac off, then the triac is good. If half the supply voltage is measured, the triac is defective. If very low, or zero voltage is measured, there could be a defective triac or a defective control board.

Perform the above procedure for testing triacs. If the voltage measured is very low or zero, then substitute a control board known to be in good working order.

Spitting or unusual steaming from

sprayhead or air vents. (Water too

hot)

1. Triac

2. Lime Buildup

CAUTION - Tank and tank components should be delimed regularly depending on local water conditions. Excessive mineral buildup on stainless steel surfaces can initiate corrosive reactions resulting in serious leaks.

Inspect the tank assembly for excessive lime deposits. Delime as required.

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41746 112008

TROUBLESHOOTING (cont.)

Problem

Spitting or unusual steaming from sprayhead or air vents. (Water too hot) (cont.)

Inconsistent beverage level in server.

Possible Cause

3. Electronic control board

1. Strainer/flow control (.750 GPM)

2. Improper water pressure

3. Brew Valve

Troubleshooting Procedures

Perform the previous procedure for testing triacs. If the voltage measured is very low or zero, then substitute a control board known to be in good working order.

(A) Direction of ﬂow arrow must be pointing towards the brewer.

(B) Remove the strainer/ﬂow control and check for obstructions. Clear or replace.

Check operating water pressure to the brewer. It must be between 20 and 90 psi (138 and 620 kPa).

Test the Brew Valve. Refer to Testing Individual Components. Turn the valve on for 30 seconds and collect the water dispensed from the sprayhead. Repeat the test several times to conﬁrm a consistent volume of dispensed water. If not consistent, check the valve, tubing and sprayhead for lime buildup.

4. Bypass Valve

5. Lime buildup

Page 12

If bypass is being used on the inconsistent brewing recipe, test the Bypass Valve. Refer to Testing Individual Components. Turn the valve on for 30 seconds and collect the water collected from the bypass opening. Repeat the test several times to conﬁrm a consistent volume of dispensed water. If not consistent, check the valve, tubing and bypass opening for lime buildup.

Inspect for lime buildup that could block the tank, tank ﬁttings, tubing, valves and sprayhead.

41746 112008

TROUBLESHOOTING (cont.)

Problem Possible Cause

Consistently high or low beverage

1. Brew Volume adjustment

level in server.

Dripping from sprayhead.

Water overﬂows ﬁlter.

1. Brew Valve

1. Type of paper ﬁlters

2. No sprayhead

Beverage overﬂows server.

1. Beverage left in server from previous brew

2. Brew Volume adjustment

Troubleshooting Procedures

Adjust the brew volume as required to achieve the recommended volume for each brew cycle.

Repair or replace leaky valve.

BUNN paper ﬁlters should be used for proper extraction.

Check sprayhead

The brew cycle should be started only with an empty server under the funnel.

Adjust the brew volume as required to achieve the recommended volume for each brew cycle.

Weak beverage.

1. Type of paper ﬁlters

2. Coffee

3. Sprayhead

4. Funnel Loading

5. Water temperature

BUNN paper ﬁlters should be used for proper extraction.

A sufﬁcient quantity of fresh drip or regular grind should be used for proper extraction.

The correct B.O.M. sprayhead should be used to properly wet the bed of ground coffee in the funnel.

The BUNN paper ﬁlter should be centered in the funnel and the bed of ground coffee leveled by gentle shaking.

Empty the server, remove its cover, and place the server beneath the sprayhead. Place empty funnel over the server entrance, with ON/OFF switch in the "ON" position press the start switch and release it. Check the water temperature immediately below the sprayhead with a thermometer. The reading should not be less than 195˚F (91˚C).

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41746 112008

TROUBLESHOOTING (cont.)

Problem

Weak beverage (cont.)

Brewer is making unusual noises.

Possible Cause Troubleshooting Procedures

6. Incorrect Recipe

Consider adjusting bypass percentage, preinfusion, or pulse brew. Contact Bunn-O-Matic for suggestions.

1. Solenoid (Inlet)

The nut on back of the solenoid must be tight or it will vibrate during operation

2. Plumbing lines

Plumbing lines should not be resting on the counter top.

3. Water Supply

(A) The brewer must be connected to a cold water line.

(B) Water pressure to the brewer must not be higher than 90 psi (620 kPa). Install a regulator if necessary to lower the working pressure to approximately 50 psi (345 kPa).

4. Tank Heaters.

Remove and clean lime off tank heaters.

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TROUBLESHOOTING (cont.)

SERVICE TOOLS

This function allows the testing of individual com-

ponents and the ability to check switches for proper

function. This function also tests the Soft Heat server's

status on the brewer (in place or removed), and the

funnel sensor coil's frequency (diagnostic tool for

troubleshooting purposes only).

Testing individual components (outputs):

This will allow the operator to test the operation

of individual components and outputs of the brewer.

The components that can be individually tested are as

follows:

SINGLE Brewers

Brew Valve

Bypass Valve

Funnel Lock (Optional)

Server (SH models only)

Reﬁll Valve

Tank Heaters

Heater Contactor

DUAL Brewers

Left Brew Valve

Left Bypass

Left Funnel Lock (Optional)

Left Server (SH models only)

Right Brew Valve

Right Bypass

Right Funel Lock (Optional)

Right Server (SH models only)

Reﬁll Valve

Tank Heaters

Heater Contactor

Procedure to test components (outputs):

1. Place brew funnel(s) into rails on the brewer (both sides on DUAL brewers).

2. Place server(s) beneath the brew funnel(s).

3. Press and hold the upper right hidden switch until display reads UNITS. Release the switch. Continue to press and release switch until SERVICE TOOLS appears.

4. Press YES to run tests on various components and outputs within the brewer. Pressing NO will exit this function and advance to next function screen.

5. The display should read TEST OUTPUTS.

Page 15

6. Press and release YES. The display should read: BREW VALVE on SINGLE brewers

LEFT BREW VALVE on DUAL brewers.

7. To test BREW VALVE, press ON. If the brew valve is functional, water should run from the brewer (left side on DUAL brewers)

8. Press OFF to end ﬂow of water.

9. Press NEXT to advance to the next component to be tested.

NOTE: To bypass testing any component, press NEXT to advance to the next one, without testing the previous component.

10. To test BREW BYPASS on SINGLE brewers or LEFT BREW BYPASS on DUAL brewers, press ON. If the bypass valve is functional, water should run from the brew bypass (left side on DUAL brewers).

11. Press OFF to end ﬂow of water.

12. Press NEXT to advance to the next component to be tested.

13. To test FUNNEL LOCK on SINGLE brewers or LEFT FUNNEL LOCK on DUAL brewers, press ON. If the funnel lock is functional, the lock will come down to hold the funnel in place.

14. Press OFF to retract the funnel lock.

15. Press NEXT to advance to the next component to be tested.

16. (SH models only) To test SERVER on SINGLE brewers or LEFT SERVER on DUAL brewers, press ON. If the server and the sensor are functional, the light on the lower right corner of the server will illuminate.

17. Press OFF to end testing of server.

18. Press NEXT to advance to the next component to be tested.

19. For DUAL brewers, follow steps 7 through 16 to test the right side components.

20. To test REFILL VALVE, press ON. If the reﬁll valve is functional, the sound of the valve operating will be heard.

21. Press OFF to end testing of reﬁll valve.

22. Press NEXT to advance to the next component to be tested.

23. To test TANK HEATERS, connect a voltmeter across each of the tank heaters to check for voltage.

24. Press ON. The correct voltage should be present at the heater terminals.

25. Press OFF to end testing of the tank heaters.

41746 112008

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