Bunn G1 User Manual

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P

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 [phone] 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.

2

10191 070306

SPECIAL

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3

ELECTRICAL REQUIREMENTS

The 120 volt and 240 volt grinders have an attached cordset and requires 2-wire, grounded service rated
120 volts ac and 240 volts ac, 15 amp, single phase, 60 Hz. The 230 volt grinders have a power connector and
requires 2-wire, grounded service rated 230 volts ac, 15 amp, single phase, 50 Hz.

INITIAL SET-UP

CAUTION - Unplug the grinder throughout the initial set-up.

1. Open the top lid. Clear all foreign objects and shipping materials from the hopper compartment and the

entrance to the grind chamber.

2. Tip the machine gently, on its back, so it rests with approximately one inch of the bottom overhanging the

work surface.

3. Remove the drawer from the base assembly.

4. Place the base against the grinder bottom and align the four sets of holes.

5. Securely fasten the base to the grinder bottom using the four screws and washers provided.

6. Raise the grinder to the upright position.

7. Insert the drawer into the base assembly.

8. The grinder can now be plugged-in and put into service.

OPERATING CONTROLS

Off/On/Start Switch

OFF - (upper position)
Switching to this position stops the operation of the grinder.
ON - (center, resting position)
The switch will return to this position after a grind cycle has begun and will remain in this position after grinding
has ceased.
START - (lower, momentary position)
Pressing the switch initiates grinding only when a bag is in place behind the chute.

Grind Selector

Allows the user to vary the grind for each bag of coffee. Each setting will provide precisely the same grind every
time it is selected.

Bag Sensor

Prevents the grinder from operating unless the back of a bag is in place behind the dispense chute.

Do not attempt to bypass this safety device.

CLEANING

The use of a damp cloth rinsed in any mild, non-abrasive, liquid detergent is recommended for cleaning all
surfaces on Bunn-O-Matic equipment. Regular cleaning will keep your grinder looking new for years

4

10191 011500

COFFEE GRINDING

1. Turn the selector knob to align the red arrow with the desired grind.

2. Raise the top lid and add the whole bean coffee. Close the top lid.

3. Locate the back of a bag behind the dispense chute. (The grinder will not operate unless the bag is behind
the chute.)

4. Allow the bag to rest on the screen beneath the chute.

5. Press the start switch.

6. Flip the cleaning lever a few times as dispensing slows.

7. Remove the bag when ground coffee is no longer dispensed from the chute. The grinder will stop automati­cally as the bag is removed.

NOTE - The start switch will have to be pressed again to continue the cycle if the bag is removed while grind-

ing.

ADJUSTMENT

1. Place an empty bag on the screen, with the back of the bag behind the dispense chute.

2. Start the grinder to clear the grind chamber. Leave grinder “ON”.

3. Turn the Grind Selector knob to the “TURKISH” (fully clockwise) position.

4. Using a small flat blade screwdriver, loosen the two set screws on the left side of the grind selector knob.

5. Hold the knob in the “TURKISH” (fully clockwise) position with one hand.

6. Using a large flat blade screwdriver, slowly turn the adjusting screw in the center of the grind selector knob
to the right (clockwise) until a metallic whine can be heard due to the rubbing of the grinding burrs.

7. While holding the knob in the “TURKISH” (fully clockwise) position, back off the screw to the left (counter­clockwise) just until the metallic whine ceases.

8. Turn-off the grinder.

9. Push the knob against the dial plate and tighten both set screws on the left side of the grind selector
knob.

10. Turn the grinder on and listen again for the metallic whine with the grind selector knob in the turkish (fully
clockwise) position. If the metallic whine is heard, repeat steps 7 through 10 until the sound ceases.

11. If no metallic whine is heard, the grinding burrs are adjusted properly.

5

10191 011500

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.

WARNING – • Exercise extreme caution when servicing electrical equipment.

• Disconnect the grinder from the power source when servicing, except when electrical tests
are specified.

• Follow recommended service procedures

• Replace all protective shields or safety notices

PROBLEM

Grinder will not start.

PROBABLE CAUSE

1. No power or incorrect voltage.

2. Off/On/Start Switch.

3. Bag sensor.

REMEDY

(A) Plug-in the grinder.
(B) Check the voltage at the wall out­let with a voltmeter. It must be 120
volts ac for two wire 120 volt models
or 230 volts ac for two wire 230 volt
50 Hz models or 240 volts ac for two
wire 240 volt 60 Hz models.

(A) Press the switch to the “START”
position.

(B) Refer to Service - Off/On/Start
Switch for testing procedures. See
page 16.

(A) The receiving bag must be placed
on the tray screen and have the back
of the bag behind the dispense chute
to activate the sensor switch.

6

10191 011500

TROUBLESHOOTING (cont.)

PROBLEM

Grinder will not start. (cont.)

Grinder will not shut off.

PROBABLE CAUSE

3. Bag Sensor. (cont.)

4. Motor overload protector.

1. Off/On/Start Switch

REMEDY

(B) Refer to Service - Bag Sensor
Switch for testing and adjustment
procedures. See page 9.

Remove the plug located on the
right side of the housing. Press the
red “Reset” button visible through
the opening. Listen carefully for a
“click”. This resets the motor protec­tion circuit and may indicate that an
overload has been encountered by
the motor. (An overload can occur
when something other than coffee is
inserted into the hopper for grinding.
Refer to Service - Motor for disas­sembly.) See page 10 for AC Motors
or see page 13 for DC Motors.

(A) Move the switch to the “OFF”
position.

2. Bag Sensor

3. Relay

(B) Refer to Service - Off/On/Start
Switch for testing procedures. See
page 16.

(A) Remove bag from under the
dispense chute.

(B) Refer to Service - Bag Sensor
Switch for testing procedures. See
page 9.

Refer to Service - Relay for testing
procedures. See page 18.

7

10191 011500

TROUBLESHOOTING (cont.)

PROBLEM

Grinder starts, but will not dis­pense.

PROBABLE CAUSE

1. Hopper

2. Entrance to grind chamber

3.Shear Plate

REMEDY

Coffee must be poured into hopper
before grinding.

Foreign materials must not block
the opening at the bottom of the
hopper.

Remove both black fillister head
screws holding the grinder selector
dial plate to the grinder. Carefully
remove the dial plate and rotor cup.
Inspect the shear plate for wear.
Replace if excessively worn or dam­aged.

8

10191 011500

CONTENTS

Bag Sensor Switch ..............................................9

Motor and Grind Chamber (AC) ........................10

Motor and Grind Chamber (DC) ........................13

Off/On/Start Switch ...........................................16

Rectifier ............................................................17

Relay .................................................................18

Wiring Diagrams ..........................................20,21

9

SERVICE (cont)

BAG SENSOR SWITCH (cont.)

4. Disconnect the grinder from the power source.

If voltage is present as described, proceed to

#5.

If voltage is not present as described, refer to the

Wiring Diagrams and check the grinder wiring
harness.

5. Check for continuity across the terminals on the

bag sensor switch.

If continuity is present as described, reconnect the
wires, the switch is operating properly.
If continuity is not present as described, replace the
switch.

Removal and Replacement:

1. Remove the wires from the switch.

2. Remove the two #8-32 keps nuts securing the

bag sensor assembly to the grinder housing.

3. Remove the two #2-56 screws, nuts and external

tooth lockwashers securing the switch to the bag
sensor assembly.

4. Mount the new switch to the bag sensor assembly

using two #2-56 screws, nuts and external tooth
lockwashers. Adjust the assembly by locating the
corner of the switch housing to the top edge of
the black metal mounting bracket.

5. Reattach the sensor assembly to the grinder

housing and secure with two #8-32 keps nuts.

6. Refer to Fig. 3 when reconnecting the wires.

AC MOTOR AND GRIND CHAMBER

WHI/ORA to
Terminal “A”
on Relay

FIG. 3 BAG SENSOR SWITCH TERMINALS

10

SERVICE (cont,)

AC MOTOR AND GRIND CHAMBER (cont.)

4. Check the voltage across the white, red or red/
black and white/blue wires on terminals L1 &
L2 with a voltmeter. Connect the grinder to the
power source. When the Off/On/Start switch is
momentarily placed in the “START” (lower) posi­tion and then left in the “ON” (center) position
and a bag is in place behind the coffee dispense
chute.Plug-in the grinder. The indication must
be:

a. 120 volts ac for two wire 120 volt models.
b. 230 volts ac for two wire 230 volt models
c. 240 volts ac for two wire 240 volt models.

5. Disconnect the grinder from the power source.

If voltage is present as described replace the motor.
If voltage is not present as described, reconnect the
white, red or red/black and white/blue wires to the
motor, refer to the Wiring Diagrams and check the
grinder wiring harness.

Removal and Replacement - Motor (Refer to FIG.6):

1. Remove the plate on the rear of the motor and
disconnect all wires from the motor.

2. Remove the two .250”-20 screws (1) securing
grind selector dial plate and grind selector knob
(2) to the grind chamber. Remove dial plate and
selector knob as an assembly.

3. Slide burr (7), auger rotor/spring assembly (3),
shear plate (4) and burr rotor cup (5) off the
grinder motor shaft as an assembly.

4. Remove the two .250”-20 screws (8) securing
the stationary burr (9) to the grind chamber.

5. Remove bushing (10) and shaft extension (11)
from the grinder motor shaft.

6. Remove the two #8 thread forming screws (12)
securing the fill plate (13) to grinder housing and
remove plate (13).

7. Remove the four #10-24 screws (14) securing
the chute assembly (15) to the grind chamber
and remove chute assembly (15).

8. Remove the four .250”-20 screws, flat washer
and rubber washers securing the motor to the
mounting bracket.

9. Remove motor out the rear of the grinder hous­ing.

10. Remove the four .250”-20 cage nuts from the
motor mount.

11. Clean all grinding burrs and mounting surfaces
before reassembly.

12. Install the four .250”-20 cage nuts on the new
motor.

13. Place the new motor with hopper collar and bush­ing into position on the bushings on the motor
mounting bracket.

14. Using four .250”-20 screws, flat washers and
rubber washers secure the motor to the mounting
bracket.

15. Install stationary burr (9) to the grind chamber
housing using two .250”-20 screws.

16. Install burr (7) and burr auger rotor/spring as­sembly (3) on to motor shaft.

17. Install motor shaft extension (11) on motor
shaft.

18. Align the slot in the motor shaft extension (11)
with the slot in the burr auger rotor/spring as­sembly (6) and install shear plate (4).

19. Install burr rotor cup (5).

20. Install grind selector dial plate and grind selector
knob assembly on the grind chamber housing and
secure with two .250”-20 screws.

21. Refer to Fig. 5 and reconnect the wires.

22. Refer to ADJUSTMENTS on page 5 and reset the
burrs.

WHI/BLU to
Relay N.O.(K4)
WHI to Cordset (120V)
RED/BLK to Cordset (230V)

GRN to Ground (120V)
GRN/YEL to Ground (230V)

FIG. 5 AC MOTOR TERMINALS

Removal and Replacement - Grind Chamber - Refer
to Fig. 6:

1. Loosen the two set screws (16) securing the grind
selector knob to the grind selector dial plate (18)
and remove knob.

2. Remove the adjusting screw w/bearing (19).
Inspect adjusting screw w/bearing for wear.
Replace if excessively worn or damaged.

11

P1310

10191 011500

SERVICE (cont.)

12

SERVICE (cont.)

17. Install grind selector dial plate (18) with adjusting
screw w/bearing (19) onto the grind chamber and
secure with two .250”-20 screws (1).

18. Install grind selector knob (17) onto the grind
selector dial plate (18).

NOTE: Refer to ADJUSTMENTS and reset the burrs.

DC MOTOR AND GRIND CHAMBER - G1MD ONLY

13

SERVICE (cont,)

DC MOTOR AND GRIND CHAMBER - G1MD ONLY
(cont.)

14

SERVICE (cont,)

DC MOTOR AND GRIND CHAMBER - G1MD ONLY
(cont.)

15

SERVICE (cont,)

OFF/ON/ START SWITCH

Location:
The Off/On/Start switch is located in the up­per front wrapper above and to the right of the grind
selector knob (left side when viewed from rear).
Test Procedure:

1. Disconnect the grinder from the power source.

2. Check the voltage across the black wire on the
Off/On/Start switch and the white wire or the red/
black on the relay coil with a voltmeter. Connect
the grinder to the power source. The indication
must be:

a. 120 volts ac for two wire 120 volt models.
b. 230 volts ac for two wire 230 volt models.
c. 240 volts ac for two wire 240 volt models.

3. Disconnect the grinder from the power source.

If voltage is present as described, proceed to #4.
If voltage is not present as described, refer to the
Wiring Diagrams and check the grinder wiring har­ness.

If continuity is present as described, proceed to #6.
If continuity is not present as described, replace the
switch.

6. Check for continuity across the two 3/16” ter­minals when the switch is held in the “START”
(lower) position. Continuity must not be present
across these terminals in the “OFF” (upper) or
“ON” (center) positions.

If continuity is present as described, the Off/On/Start
switch is operating properly, reconnect the four
wires.
If continuity is not present as described, replace the
switch.

Removal and Replacement:

1. Remove all wires from the switch terminals.

2. Compress the clips inside the front wrapper and
gently push the switch through the opening.

3. Push the new switch into the opening and spread
the clips to hold the switch in the hood.

4. Refer to Fig. 11 when reconnecting the wires.

WHI/RED

WHI/VIO to
Bag Sensor
Switch

WHI/RED to
Relay 7

BLK to
Cordset

WHI/VIO to
Relay 6

P606

FIG. 11 OFF/ON/START SWITCH TERMINALS

4. Remove all four wires from the switch.

5. Check for continuity across the two 1/4” terminals
when the switch is held in both the “ON” (center)
and “START” (lower) positions. Continuity must
not be present across these terminals in the “OFF”
(upper) position.

16

+

A

C

A

C

SERVICE (cont.)

RECTIFIER - G1MD ONLY

Removal and Replacement:

1. Disconnect the wires from the rectifier.

2. Remove the #10-32 screw securing the rectifier
to the motor mounting bracket.

3. Remove the rectifier and discard.

4. Install new rectifier on the rear of the motor
mounting bracket and secure with a #10-32
screw.

5. Refer to Fig. 13 and reconnect the wires.

BLK from Motor (+)

BLU to BLU from Motor (AC)

WHI from Main Harness (AC)

RED from Motor (-)

FIG. 13 RECTIFIER TERMINALS

P1381

17

SERVICE (cont,)

RELAY

Location:
The relay is located on the grinder base inside
the lower housing.

Test Procedure:

1. Disconnect the grinder from the power source
and place a coffee bag behind the dispense
chute.

2. Check the voltage across the white/orange and
white or red/black wires on terminals A & B of
the relay with a voltmeter. Hold the Off/On/Start
switch in the “START” (lower) position and con­nect the grinder to the power source. The indica­tion must be:

a. 120 volts ac for two wire 120 volt models.
b. 230 volts ac for two wire 230 volt models.
c. 240 volts ac for two wire 240 volt models

3. Disconnect the grinder from the power source.

If voltage is present as described, proceed to #4.
If voltage is not present as described, refer to the Wir­ing Diagrams and check the grinder wiring harness.

4. Remove the white/red wires from relay contacts
7 & 9.

5. Check the voltage across the white wire or red/
black on terminal B and either white/red wire with
a voltmeter. Place the Off/On/Start in either the

“ON” (center) position or “START” (lower) posi­tion. Connect the grinder to the power source.

The indication must be:
a. 120 volts ac for two wire 120 volt models.
b. 230 volts ac for two wire 230 volt 50 Hz mod-

els.
c. 240 volts ac for two wire 240 volt 60 Hz mod-

els.

6. Disconnect the grinder from the power source.

7. Check the voltage across terminal B and the

remaining white/red wire with a voltmeter. Place

the Off/On/Start switch in either the “ON” (center)

position or “START (lower) position. Connect the

grinder to the power source. The indication must

be:
a. 120 volts ac for two wire 120 volt models.
b. 230 volts ac for two wire 230 volt 50 Hz mod-

els.
c. 240 volts ac for two wire 240 volt 60 Hz mod-

els.

8. Disconnect the grinder from the power source.

If voltage is present as described, proceed to #9.
If voltage is not present as described, refer to the Wir­ing Diagrams and check the grinder wiring harness.

9. Remove the white/violet wire from terminal 6 and

white/blue wire from terminal 4.

10. Check for continuity across terminals 7 & 4.

Connect the grinder to the power source. Continu-

itymust be present when the Off/On/Start switch

is momentarily placed in the “START” (lower)

position and a bag is in place behind the coffee

dispense chute.

11. Check for continuity across terminals 9 & 6. Con-

nect the grinder to the power source. Continuity

must be present when the Off/On/Start switch

is momentarily placed in the “START” (lower)

position and a bag is in place behind the coffee

dispense chute.

12. Disconnect the grinder from the power source.

If continuity is present as described, reconnect the
wires, the relay is operating properly.
If continuity is not present as described, replace the
relay.

18

19

WHI/VIO

WHI/VIO

WHI/BLU

WHI/ORA

1 or A

GRN

L1

N

SW1

BLK WHI/RED

SW2

K

0 or B

M

L1 L2

120 VOLT AC

2 WIRE

SINGLE PHASE 60 HZ

WHI

WHI

K-2 or K-7

K-8 or K-9

K-6

K-4

SCHEMATIC WIRING DIAGRAM G1, G2 & G3

10190.0000G 07/05 © 1985 BUNN-O-MATIC CORPORATION

20

10191 070306

WHI/VIO

WHI/VIO

WHI/BLU

WHI/ORA

SCHEMATIC WIRING DIAGRAM G1A, G2A & G3A

GRN/YEL

L1

L2

SW1

BLK

WHI/RED

WHI/RED

SW2

N.O.

N.O.

M

L1

L2

RED (230V)

RED/BLK (240V)

RED (230V)

RED/BLK (240V)

10754.0000E 07/05 © 1993 BUNN-O-MATIC CORPORATION

K-4

K-6

230 VOLTS AC
240 VOLTS AC

2 WIRE

SINGLE PHASE

K

1 or A 0 or B

K-2 or K-7

K-8 or K-9

21

10191 070306