Bunn U3A service manual Control Thermostat

Page 17

SERVICE (cont.)

CONTROL THERMOSTAT

FIG. 6 CONTROL THERMOSTAT

P2209.60

 

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.

3.Connect the brewer to the power source.

Model

Check Voltage Across

Voltage

120/208V & 120

Black wire on thermostat

120V

240V - 3 wire w/

from main harness to white

 

ground single phase

wire in terminal block.

 

not be present when the thermostat is in the "OFF" position (fully counterclockwise).

If continuity is present as described, the control ther- mostat is operating properly.

If continuity is not present as described, replace the control thermostat.

Removal and Replacement:

1.

Disconnect the wires from the control thermo-

 

stat.

2.

Remove the thermostat capillary bulb by firmly

 

pulling up on the capillary at the component

 

bracket. This will disengage the grommet from

 

the component bracket.

3.

Remove the #8-32 screw securing the control

 

thermostat and mounting bracket to the component

 

bracket. Remove control thermostat and bracket

 

as an assembly.

4.

Remove knob from control thermostat.

5.

Remove the two #6-32 screws securing the control

 

thermostat to the thermostat mounting bracket.

 

Remove and discard thermostat.

6.

Install new control thermostat on thermostat

 

mounting bracket and secure with two #6-32

 

screw.

7.

Install knob on thermostat.

8.

Install thermostat and mounting bracket on the

 

component bracket and secure with one #8-32

230V - 2 wire w/ ground single phase

208V or 240V - 2 wire w/ground single phase

280V or 440V - 4 wire w/ground 3 phase

380V - 3 wire w/ ground 3 phase w/ stepdown

transformer

Red wire on thermostat

230V

from main harness to black

 

wire in terminal block.

 

Black wire on thermostat

208V or

from main harness to red

240V

wire in the terminal block.

 

Black wire on thermostat

220V or

from main harness to white

254V

wire in terminal block.

 

Black wire on thermostat

120V

from main harness to white

 

wire on step down trans-

 

former.

 

screw.

9. Carefully bend the capillary tube so that the tube

and bulb inside the brewer are in the vertical posi-

tion.

NOTE: The capillary tube must be clear of any electrical termination and not kinked.

10.Refer to Fig. 7 and reconnect the wires.

11.Adjust the control thermostat as required.

BLK from Main Har- ness (All Models Ex- cept 230V CE Models RED from Main Harness (230V CE Models)

4.Disconnect the brewer from the power source. If voltage is present as described, proceed to #5.

If voltage is not present as described, refer to theWiring Diagrams and check the brewer wiring harness.

5.Disconnect the black wires from the control ther- mostat.

6.Check for continuity across the terminals on the control thermostat with the control thermostat in the "ON" position (fully clockwise), continuity must

BLK to Limit Thermostat (All Models Except 230V CE Models

RED to Limit Thermostat (230V CE Models)

P1730.80

FIG. 7 CONTROL THERMOSTAT TERMINALS

Page 17

10060

080900

 

Image 17
Contents Phone 217 529-6601 FAX 217 U3ABUNN-O-MATIC Commercial Product Warranty User Notices IntroductionElectrical Requirements Electrical Installation InstructionsPlumbing Requirements Initial SetupCE Requirements Adjusting Brew Volumes Initial SetupFilter Holder CleaningCoffee Brewing Problem Probable Cause TroubleshootingBrew cycle will not start No water BrewerTroubleshooting Remedy ProblemUse Bunn filters made for the U3 brewer Remove obstruction Refer to Service Circuit Breaker for testing procedures. SeeRemove and clean lime off the tank heater. See Contents ServiceComponent Access Location ServiceWire Models and 440V Four Wire Models Contactor ContactorService Contactor Control Thermostat Fuse and Fuse Hilder Limit thermostat Limit ThermostatLiquid Level Board and Level Probe Reconnect the blue wire to T1 on the liquid level boardModel Voltage Jumper Not TouchingLiquid Level Board Terminals BLK from Main Harness RED to Main Harness ON/OFF SwitchTest Procedures Disconnect the brewer from the power source Pump Assembly Pump AssemblyIf voltage is present as described, proceed to #3 Relay Brewers W/BREW LockoutRefer to and reconnect the wires BLU from Start Switch Removal and Replacement Disconnect the wires from the relayBrew Timer BLU to Start Switch BLU from Brew TimerSelector Switch Half BATCHP1317.30 Selector Switch Half Batch OptionSolenoid SolenoidEarly Models Start Switch Brew Start Switch BrewTank Heater Tank HeatersThermal Fuses 230V-CE Models only Timer Early ModelsDisconnect the black and white wires to the pump Service Timer Early ModelscontIf voltage is present as described, proceed to #8 Harness BLK to Pump Lead WHI to Pump LeadIf voltage is as described, proceed to #7 Service Digital Timer Late ModelsAdjust the timer as described below Timer Setting Digital Timer Terminals Remove the transformer and discard TransformerMaster ON/OFF Switch LOC Service Master ON/OFF Switch Late Models120/208 Volts AC 120/240 Volts AC 3 Wire + GND Single Phase 10060 080900 10060 080900 Schematic Wiring Diagram U3A CE Schematic Wiring Diagram U3833 Schematic Wiring Digram U3833

U3A, U3 specifications

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