Blodgett MT3255 Service Manual

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Page 1

MT3255 AND MT3270 SERIES

CONVEYOR OVEN

SERVICE AND REPAIR MANUAL

BLODGETT OVEN COMPANY

www.blodgettcorp.com

50 Lakeside Avenue, Box 586, Burlington, Vermont 05402 USA Telephone (802) 658Ć6600 Fax: (802)864Ć0183

PN M8561 Rev B (6/01)

Duplication of the information in this manual is prohibited without the consent of the Blodgett Service Department.

Page 2

TABLE OF CONTENTS

1. INTRODUCTION

Oven Specifications 1-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Ventilation Requirements 1-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Electrical Specifications 1-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Gas Specifications 1-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Illustrated Parts Lists 1-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2. ASSEMBLY

Oven Assembly Procedures 2-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Return Air Diverters 2-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Air Nozzles 2-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Conveyor Belt Supports 2-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Wire Conveyor Belt 2-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Drive Chain 2-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

End Plugs 2-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Crumb Pans 2-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Window Handle 2-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3. OPERATION

Standard Control Options 3-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

U.E. Temperature Controller with Open Loop DC Drive System 3-1. . . . . . . . . . . . . . . . . . . . .

U.E. Temperature Controller with Closed Loop DC Drive System 3-2. . . . . . . . . . . . . . . . . . . .

Athena Temperature Controller with Open Loop DC Drive System 3-3. . . . . . . . . . . . . . . . . . .

Athena Temperature Controller with Closed Loop DC Drive System 3-4. . . . . . . . . . . . . . . . .

Computer Controller 3-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Sequence of Operation 3-7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

MTĆ70ĆPH Domestic - M2468 Rev E 3-7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

MTĆ70ĆPH General Export - M2501 Rev D 3-9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

MT3270 with Standard Controls - 21575 Rev E 3-11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

MT3270 Twin Belt with Remote Controls - M4410 Rev A 3-13. . . . . . . . . . . . . . . . . . . . . . . . . . .

MT3270 with Closed Loop - M4206 Rev B 3-15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

MT3255E - M4289 Rev B 3-17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

MT3270 CE - M8296 Rev A 3-19. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Oven Adjustments for Cooking 3-28. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Temperature 3-28. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Conveyor Speed Time vs. Temperature 3-28. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Air Flow Adjustments 3-28. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4. CALIBRATION AND ADJUSTMENT

Convection Blower Motors 4-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Regulated Gas Pressure 4-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Standard Controller Configuration 4-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Page 3

TABLE OF CONTENTS

Belt Speed Calibration - Closed Loop 4-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Belt Speed Calibration - Open Loop 4-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Temperature Calibration - United Electric Controller 4-6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Temperature Calibration - Athena Controller 4-7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Computer Controller Configuration 4-9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Computer Controls 4-9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Temperature Calibration 4-11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Belt Speed Calibration 4-12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Motor Control Board Adjustment 4-13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Rerating the Appliance 4-15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Checking the Firing Rate 4-16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5. TROUBLESHOOTING

DC Drive System 5-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Convection System 5-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Heating System 5-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Computer Control System 5-6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6. TECHNICAL APPENDIX

Intermittent Ignition System 6-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Principles of Operation 6-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Service Procedures 6-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Cooking Computer - Temperature vs Resistance 6-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Thermoelectric Voltage in Absoluter Millivolts - Type J Thermocouple 6-5. . . . . . . . . . . . . . . . . .

Conversion Factors 6-6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Pressure Conversion 6-7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Page 4

CHAPTER 1

INTRODUCTION

Page 5

MT3255 and MT3270

OVEN SPECIFICATIONS

VENTILATION REQUIREMENTS

The hood should completely cover the unit with an overhang of at least 6" (15 cm) on all sides not adjaĆ cent to a wall. The distance from the floor to the lower edge of the hood should not exceed 7' (2.1 m). The ventilation system should replace 80% of the exhaust volume with fresh make up air. TABLE 1 should be used as a guideline.

Single Double Triple

CFM 1200Ć1650 2400Ć3300 3600Ć5000

M3/min 34 Ć 47 68Ć93 102Ć142

TABLE 1

ELECTRICAL SPECIFICATIONS

NOTE: Three Phase hookup is not permitted on

gas models.

WARNING: DO NOT INSTALL A HIGH LEG" TO ANY CONVEYOR OVEN!

Installations within the U.S.

The MT3255 and MT3270 require a 15 Amp, 60HZ, 1F, 208Ć240VAC, 4 wire service consisting of L1, L2, neutral and ground. See FIGURE 1. Use 90C wire and size to National Electric or local codes.

Installations outside the U.S.

The MT3255G and MT3270 require a 15 Amp, 50Hz, 1F, 230 VAC, 3 wire service consisting of L1, neutral and ground. See FIGURE 1. Use 90C wire and size wire according to local codes.

The MT3255E is available in two voltage options. The 380/220 VAC oven requires a 52 Amp, 50Hz, 3F, 4 wire service consisting of L1, L2 neutral and ground. The 415/240 oven requires a 48 Amp, 50Hz, 3F, 3 wire service consisting of L1, neutral and ground. See FIGURE 1. Use 90C wire and size wire according to local codes.

120

208Ć240

U.S. Installations Export Installations - Gas Models

110

380/220

Export Installations - MT3255E

OvenSupply

FIGURE 1

220Ć230

415/240

OvenSupply

Export Installations - MT3255E

1-1

Page 6

INTRODUCTION

CE approved installations

Connect the oven to a separate group 230V, 50 hz with rigid connection and circuit breaker. The cirĆ cuit breaker should disconnect all poles, including neutral with a contact separation of at least 3 mm. See FIGURE 2. Use 90C wire and size according to local codes.

Blodgett

Connector

230

1 2

OvenSupply

NOTE: The burner control unit is phase sensitive.

If the phase and neutral are switched the control locks out.

Connect exhaust fan connector 1 and 2. See FIGURE 2. Connect phase + neutral + ground.

2Ć4Ć92

Relay A

Fan

21Air Pressure Regulator

Burner Control Solenoid

MT1828G CE Approved Installations

FIGURE 2

1-2

Page 7

MT3255 and MT3270

GAS SPECIFICATIONS

GAS CONNECTIONS

Domestic and General Export installations

The gas line should be large enough to accommoĆ date the peak demand of all the gas appliances. TABLE 2 reflects a straight line, 50 foot run with no coupling restrictions and no other appliances drawing service. Gas line installations MUST conĆ form to National Fuel Gas Code NFPA 54/ANSI Z223.1 Sec. 1.4 (Latest Edition). TABLE 2 should be used as a guideline only.

NOTE: For any pipe runs over 50 feet (15 m), conĆ

sult the factory.

CE approved installations

1. Connect the oven to the gas line with the propĆ er type of gas according to Local and National Installation Standards. See TABLE 2.

DOMESTIC AND GENERAL EXPORT

Natural Gas Propane Gas

Gas Line Sizing

GAS REQUIREMENTS

The firing rate for the MT3255 and MT3270 is 150,000 BTU/Hr. (43.9 kW/Hr.)

NOTE: For natural gas meter sizing, consult your

local gas company to ensure that your meĆ ter will provide the proper supply.

Installations within the U.S.

1. Add the total BTU's/hr of all the gas appliances.

2. Convert BTU's to cubic ft/hr using the formula Cu Ft/Hr = 1000 BTU/Hr for natural gas.

3. Size the meter accordingly.

Installations outside the U.S.

1. Add the total M3/min of all the appliances.

2. Size the meter accordingly.

Single

Double

Triple

Orifice Size #1 #29

Incoming Gas Pressure W.C. kPa mbar W.C. kPa mbar

Static

Operational

CE APPROVED UNITS

Type of

Gas

G25 25 12 5,80 16 2 x 0,63 46 Nat. Gas

G20 20 8 5,80 16 2 x 0,63 46 Nat. Gas

G20/G25 20/25 Totally Inscrewed

G31 30/37/50 24 3,48 16 2 x 0,30 46 Propane

Inlet

Pressure

mbars

Burner Pressure

Pressure Regulator

5.5"

mbars

3/4" line

1Ć1/4" line

1.74

1.36

Injector

Diameter

TABLE 2

3/4" line

1 line

1Ć1/4" line

17.4

13.7

Opening

5,15 16 2 x 0,63 46 Nat. Gas

Air

12.5"

11"

Pilot

Injector

3.11

2.73

Standard

Delivery

Value kW (HS)

31.1

27.4

1-3

Page 8

ILLUSTRATED PARTS LISTS

CONVEYOR COMPONENTS

NOTE:  = ASAP Distributor Required Stocking Parts

*ą= Item too large for UPS

Ref.

Part

No.

No. Description

Ref.

Part

No.

No. Description

INTRODUCTION

21926 Belt, Wire S/S 32" SB (Per

Foot) (Total Length MT3270 18 FT, MT3255 16 FT)

23112 Belt, Wire S/S 15.75" TB (Per

Foot) (Total Length MT3270 18 FT, MT3255 16 FT)

M2379 Speed Control Board, Bodine

(After 9/90)

M3142 Speed Control Board, Minarik

(Before 9/90)

21170 Speed Control Kit, Dart to MiĆ

narik

M0705 Speed Control Board, KBIC w/

Pot.

M2254 Fuse, Line, Bodine Board, 5

AMP, 125V

M2316 Fuse, Armature, Bodine Board,

200 MA, 250V

M3145 Potentiometer, Bodine, 10 K M3143 Potentiometer, Minarik, 5 K M3144 Potentiometer, Dart, 10 K

21169 Knob, Speed Control PotenĆ

tiometer

M0200 Lock, Speed Control PotenĆ

tiometer

M0201 Dial, Speed Control PotentiomĆ

eter

M3146 Time Display, Digital M3147 Pick-Up, PV-10 (for M3146)

M3393 Speed Control, Dart Micro-

Drive

M0984 Pick-Up, PV-2 (for M3393)

M5770 Conversion Kit, Digital Time

(Open Loop) to MicroĆDrive (Closed Loop)

M3127 Motor, Conv. Drive, Bodine 90V

(Before 9/90)

M2378 Motor, Conv. Drive, Bodine

130V (After 9/90)

M2500 Brush Set, Bodine 21152 Chain, Drive Single Belt (2.33

FT)

M0391 Chain, Drive Twin Belt (Specify

5.50 FT & Order M0112)

M0112 Masterlink, Drive Chain

M2156 Cover, Drive Chain

* M1730 Conveyor Assy., Drive SB

MT3270 (Before 5/3/95)

* M6144 Conveyor Assy., Drive SB

MT3270 (After 5/3/95)

* M1731 Conveyor Assy., Idle SB

MT3270 (Before 5/3/95)

* M6145 Conveyor Assy., Idle SB

MT3270 (After 5/3/95)

* M1686 Conveyor Assy., Drive TB

MT3270 (Before 5/3/95)

* M6147 Conveyor Assy., Drive TB

MT3270 (After 5/3/95)

* M1688 Conveyor Assy., Idle TB

MT3270 (Before 5/3/95)

* M6148 Conveyor Assy., Idle TB

MT3270 (After 5/3/95)

* M1941 Conveyor Assy., Drive MT3255

* M1946 Conveyor Assy., Idle MT3255 M0109 Sprocket, Motor Drive, 12 Tooth

(1 Per Motor)

M0110 Sprocket, Conveyor Drive, 15

Tooth (Qty 1)

M1865 Sprocket, Conveyor Drive, 15

Tooth (TB Qty 1)

M0108 Sprocket, Conveyor Belt, 11

Tooth (Qty 14 SB) (Qty 16 TB)

21301 Sprocket, High Speed (Large)

M0122 Bearing, Conveyor Drive

1-4

Page 9

MT3255 and MT3270

TEMPERATURE CONTROLS

NOTE:  = ASAP Distributor Required Stocking Parts

COMPUTER CONTROLS

Part

Ref.

No. Description

No.

M6474 Computer Control Kit, Closed

Loop SB

FW525 Computer Control Kit, Closed

Loop SB (Reconditioned)

M5635 Computer Control Kit, Open

Loop TB

M3175 Decal, Lexan Control SB

M4400 Decal, Lexan Control TB

M7427 Probe, Temperature RTD, 500

OHMS

M7202 Conversion Kit, Open Loop to

Closed Loop

M3347 Cable, Computer Control, 25

Pin, 10'

M3348 Cable, Computer Control, 9

Pin, 10'

M3490 Cable, Computer Control, 25

Pin, 50'

M3491 Cable, Computer Control, 9

Pin, 50'

M3349 Harness, Inter-Connecting DC

Drive, 3ĆWire (For 9 Pin)

M3353 Harness, Relay Board (Open

Loop) (For 25 Pin) (Before 9/15/95)

M7237 Harness, Relay Board (Closed

Loop) (For 25 Pin) (After 9/15/95)

M3314 Bracket, Computer Wall

M5661 Bracket Assy., Cable Clamp

M0984 Pick-Up, PV-2

Ref.

Part

No.

No. Description

M7236 Board, Relay/Transformer

22672 Relay

M3352 Transformer, 120V to 24V

M3295 Thermostat, High Limit (Manual

Reset)

M0152 Contact, Emergency Stop

Switch

M3296 Activator, Emergency Stop

Switch (Mushroom Shape)

M3297 Nameplate, Emergency Stop

M3136 Breaker, 7 AMP Circuit

M2772 Breaker, 4 AMP Circuit

SOLID STATE CONTROLS

Ref.

Part

No.

No. Description

M7982 Controller, Analog Temperature

(Before Mid 1986)

M3149 Controller, Digital Temperature

(After Mid 1986)

M3439 Relay, Digital Temp. Controller,

10 AMP, 250V

M3150 Control Board, Temperature Hi-

Lo Limit

M3151 Thermocouple, Dual Lead (BeĆ

fore 9/90)

M3152 Thermocouple, Single Lead (AfĆ

ter 9/90)

1-5

Page 10

ELECTRICAL COMPONENTS

NOTE:  = ASAP Distributor Required Stocking Parts

INTRODUCTION

Part

Ref.

No. Description

No.

M2316 Fuse, Armature, Bodine Board,

200 MA, 250V

M2254 Fuse, Line, Bodine Board, 5

AMP, 125V

M0156 Fuse, Convection Motor

FNM-10 (Qty 8)

M0702 Fuse Block

M1821 Fuse, Control SC-4 (Qty 3)

(Before...)

M0158 Fuse Holder (Qty 3) (Before...)

M3389 Fuse, Ceramic MDA-4 (Qty 3)

(After...)

M3390 Fuse Holder (Qty 3) (After...)

M1362 Snap Disc, L140/20F, 2 Pole

SPST

M0635 Snap Disc, F110/20F, 2 Pole

SPST

M2453 Snap Disc, L140/20F, 3 Pole

SPDT (PH)

M0593 Terminal Block, 2 Pole

Ref.

Part

No.

No. Description

M0708 Contactor, 3 Pole, 120V Coil

(Convection)

M0595 Switch, Air Pressure SPDT

21124 Fan Kit, Axial (Old)

21134 Fan, Axial 30 CFM 3-1/2"

M2469 Fan, Axial 110 CFM 4-1/2"

M0571 Guard & Hardware, Fan 4" (Qty

M0572 Cord, Axial Fan 30" Power

M0152 Selector Switch, Heat & ConveyĆ

M0153 Selector Switch, Blower

M0151 Knob, Selector Switch (Heat,

Conveyor or Blower)

M1694 Cord Set & Plug Assy., 10 Foot

M0772 Receptacle, Twist Lock

16998 Relay, Interlock Hood System

SPST, 120V (PH)

16241 Relay, Alarm 3PDT, 120V (PH)

M0791 Indicator Light (PH)

CONVECTION COMPONENTS

Ref.

Part

No.

No. Description

M4224 Motor & Blower Assy., CW

M4225 Motor & Blower Assy., CCW

M5722 Insulation Kit for Blowers

MT3270

M7992 Insulation Kit for Blowers

MT3255

M5131 Nozzle Assy. w/ Diverter

MT3270/MT3255

21161 Diverter, Return Air RH

MT3270/MT3255

21162 Diverter, Return Air LH

MT3270/MT3255

AIR PLATES

Ref. No.

1-6

Part No. Description

M3905 Plate Assy., Air RH (R-L or L-R)

MT3270 Generic

M3906 Plate Assy., Air LH (R-L or L-R)

MT3270 Generic

21399 Plate Assy., Air RH (R-L or L-R)

MT3255 Generic

21400 Plate Assy., Air LH (R-L or L-R)

MT3255 Generic

24613 Hook, Air Pan

22117 Plate Assy., Block Off

MT3270/MT3255 Generic

Page 11

MT3255 and MT3270

GAS BURNER COMPONENTS

NOTE:  = ASAP Distributor Required Stocking Parts

Part

Ref.

No. Description

No.

22132 Burner Assy., Complete (Specify

Model & Gas Type)

M0767 Blower Motor, Combustion w/

Control Box

M2383 Blower Motor, Combustion

M2381 Transformer, 120V to 24V

M2382 Relay, Time Delay

M0454 Orifice, Main Burner, LP MT3270

M0455 Orifice, Main Burner, Natural

MT3270

M0579 Orifice, Main Burner, LP MT3255

M0580 Orifice, Main Burner, Natural

MT3255

M2727 Pilot Burner & Igniter Assy., LP

M2726 Pilot Burner & Igniter Assy., NatĆ

ural

M6378 Shield, Pilot Burner

M0415 Flame Sensor

M2690 Orifice, Pilot LP

M0697 Orifice, Pilot Natural

M0248 Tube, Pilot Aluminum 1/4"

M0959 Fitting, Compression 1/4"

M2799 Union, Compression

21225 Fitting, Elbow

M0279 Union, 1/2 Inch Black

1949 Nipple, Pipe 1/2 x 1-3/16 Close

M0317 Elbow, 1/2 Inch Street 90 Deg.

Ref.

Part

No.

No. Description

597 Ell, Black 90 Degree

M0590 Nipple, Pipe 1/2 x 2-1/2

17874 Ell, Black 1/2 x 3/4

23007 Spring, Solenoid Valve, LP to

Natural

18612 Spring, Solenoid Valve, Natural

to LP

23114 Conversion Kit, LP to Natural

MT3270

23113 Conversion Kit, Natural to LP

(Before 5/89) MT3270

21389 Conversion Kit, Natural to LP (AfĆ

ter 5/89) MT3270

M5259 Conversion Kit, LP to Natural

MT3255

M5290 Conversion Kit, Natural to LP

MT3255

M5495 Dual Solenoid/Pressure RegulaĆ

tor, Nat. 24V

22190 Dual Solenoid/Pressure RegulaĆ

tor, LP 24V

20287 Valve, Single Solenoid 110/120V

M0282 Valve, Manual Gas

M1054 Spark Box, 24V

21242 Connector Kit, Gas Flex 48"

21826 Connector Kit, Gas Flex 36"

M7249 Flame Tube Assy., MT3270

M6435 Flame Tube Assy., MT3255

1-7

Page 12

EXTERIOR COMPONENTS

NOTE:  = Doors are not returnable

INTRODUCTION

Part

Ref.

No. Description

No.

M3979 Decal, Control Lexan MT3270

(One Piece)

M3959 Decal, Control Lexan MT3255

(One Piece)

M4607 Crumb Pan, Idle (Solid) (Before

5/3/95)

M6164 Crumb Pan, Idle (Solid) (After

5/3/95)

M2456 Crumb Pan, Idle (w/ Holes)

(Before 5/3/95)

M6166 Crumb Pan, Idle (w/ Holes) (AfĆ

ter 5/3/95)

M4606 Crumb Pan, Drive (Solid) (BeĆ

fore 5/3/95)

M6163 Crumb Pan, Drive (Solid) (After

5/3/95)

M2458 Crumb Pan, Drive (w/ Holes)

(Before 5/3/95)

M6165 Crumb Pan, Drive (w/ Holes)

(After 5/3/95)

NOTE: Note: Crumb pans with holes are used

on middle & topsections only. The solid crumb pans are used on the bottom secĆ tion.

M2875 Stop, Product

M4304 Extension Assy., Product 15"

M4303 Extension Assy., Product 20"

M4222 Extension Assy., Product 30"

M4609 15" Product Extension &

Crumb Pan, Idle

M4608 15" Product Extension &

Crumb Pan, Drive

M4611 20" Product Extension &

Crumb Pan, Idle

M4610 20" Product Extension &

Crumb Pan, Drive

Ref.

Part

No.

No. Description

21293 End Plug, Top

M5610 End Plug, Bottom

 21172 Door, Pull Down Conversion Kit

(Before 7/89) MT3270

 M1963 Door, Pull Down (After 7/89)

MT3270

M2229 Handle, Pull Down 34" MT3270

 21888 Door, Pull Down MT3255

M2189 Handle, Door Pull Down 22"

MT3255

21935 Latch Conversion, Pull Down

Door

M1872 Plate, RH Pivot Slotted

M1871 Plate, LH Pivot Slotted

16470 Nameplate, Blodgett 10"

22229 Stacking Assy., Double

22067 Triple Base w/ Casters

21390 Legs, 17-1/4" w/ Casters

(Double) (Set of 4)

21391 Legs, 23-1/4" w/ Casters

(Single) (Set of 4)

14444 Casters, Cradle (Triple)

(Set of 4)

M5032 Chimney Kit, Single

MT3270/MT3255

M7160 Chimney Kit, Double

MT3270/MT3255

M7200 Chimney Kit, Triple

MT3270/MT3255

M2472 Body Back, MT3270 S/S

22109 Body Back, MT3255 S/S

M5020 Panel Assy., Control Box

1-8

Page 13

MT3255 and MT3270

EXCLUSIVE TO EXPORT 50 HZ

NOTE:  = ASAP Distributor Required Stocking Parts

Part

Ref.

No. Description

No.

M2245 Valve, Solenoid

M2276 Burner Assy., Complete (SpeciĆ

fy Gas Type)

M0706 Orifice, Main Burner (Specify

MTD)

M4597 Motor & Blower Assy., CW

M4598 Motor & Blower Assy., CCW

M3153 Digital Speed Control Board,

Bodine

M3154 Time Display, Digital

M3128 Motor, Straight Shaft, 180V

23034 Fan, Axial 110 CFM 4-1/2"

240V

21430 Fan, Axial 34 CFM 3-1/2" 240V

M5282 Element Assy., 220V MT3255E

M5281 Element Assy., 240V MT3255E

M6897 Element, Individual, 220V

MT3255E

M6898 Element, Individual, 240V

MT3255E

M2247 Contactor, 240V, 50 HZ

M2384 Transformer

M2385 Relay

M2386 Blower Motor, Combustion

M2630 Fuse, Line & Armature, Bodine

Board, 5 AMP 250V

M3155 Digital Temperature Controller

C

M7880 Computer Control Kit, Closed

Loop SB (CE)

M7333 Pilot Burner & Ignitor Assy., LP

(CE)

Ref.

Part

No.

No. Description

M7334 Pilot Burner & Ignitor Assy.,

Natural (CE)

M3237 Burner Assy. (CE)

M2497 Switch, Push Button (CE)

M2498 Switch, Contact (CE)

M0595 Switch, Air Pressure SPDT (CE)

M3172 Timer, Fixed, 2 Second (CE)

M3173 Timer, Fixed, 10 Second (CE)

R1530 Contactor, Mercury, 240V Coil

(CE)

M3166 Fuse, GDA-4A (CE)

M3167 Fuse Holder (CE)

M2549 Strip, Terminal (CE)

M3168 Spark Box, 240V (Landis &

Gyr) (CE)

R1586 Terminal Block, Power (CE)

R0166 Terminal Block, Ground (CE)

R1580 Stop, End (CE)

16037 Indicator Light, 250V, Red,

Round (CE & Australia)

90250 Relay, 240V 3PDT (CE)

16775 Relay, SPST, 240V, 30 AMP

(CE)

M6000 Dual Solenoid/Pressure ReguĆ

lator, Nat. (CE)

M6001 Dual Solenoid/Pressure ReguĆ

lator, LP (CE)

M3330 Switch, Air Pressure Differential

(mbr) (CE)

1-9

Page 14

MT3255E GENERAL EXPORT CONTROL BOX

(Control Plate not shown)

INTRODUCTION

1-10

Page 15

MT3255 and MT3270

MT3255G AND MT3270 DOMESTIC & GENERAL EXPORT CONTROL BOX

(Control Plate and/or Gas Burner Components not Shown)

1-11

Page 16

INTRODUCTION

MT3255 AND MT3270 CE CONTROL BOX

(Control Plate and/or Gas Burner Components not Shown)

1-12

Page 17

MT3255 and MT3270

MT3255 AND MT3270 DOMESTIC GAS BURNER COMĆ

PONENTS

(Control Box not Shown)

1-13

Page 18

INTRODUCTION

MT3255 AND MT3270 CE GAS BURNER COMPONENTS

(Control Box not Shown)

1-14

Page 19

MT3255 and MT3270

MT3255 AND MT3270 DOMESTIC & GENERAL EXPORT SB CONTROL

PLATE ASSY

1-15

Page 20

INTRODUCTION

MT3255 AND MT3270 CE SB CONTROL PLATE ASSY

1-16

Page 21

MT3255 and MT3270

MT3255 AND MT3270 EXTERIOR OVEN VIEW

1-17

Page 22

CHAPTER 2

ASSEMBLY

Page 23

MT3255 and MT3270

OVEN ASSEMBLY PROCEDURES

RETURN AIR DIVERTERS

1. Slide the return air diverters into the oven. The edge of the diverter should be 3" (7.6 cm) from the outside edge of the oven cavity.

Left Hand

Diverter

Right Hand

Diverter

CONVEYOR BELT SUPPORTS

1. Slide the left conveyor belt support (with the sprocket on the end of the shaft) into the supĆ port tracks. The sprocket must be located inĆ side the control panel after being pushed into the oven.

2. Fasten the 1/4Ć20 hex head screw from the control box into the belt support.

3. Older Oven Models - install the washer beĆ tween the control box and the tracks.

Later Oven Models - use a formed metal dimple in place of the washer.

4. Slide the right conveyor belt support into the support tracks until it touches the left support. Make sure that the rack sides do not overlap.

WIRE CONVEYOR BELT

NOTE: The conveyor belt has loops on both sides.

The belt must be installed so the loops travĆ el as shown in FIGURE 2.

1. Thread the wire belt from the right side of the oven, lower level first.

Note Orientation Of Return Air Diverters!

IMPORTANT:

FIGURE 1

AIR NOZZLES

1. Install the nozzles from the center of the oven working toward the ends. Make sure the botĆ tom of the nozzle fits into the slot of the nozzle support located at the front of the oven.

2. Secure the nozzle holdĆdown strip across the inside front of the oven using the existing screws on the wall.

2. After pushing the belt through on the lower levĆ el, leave about 12" (30.5 cm) hanging out on the left side.

3. Take the remainder of the belt, loop it around the right shaft, and push it through on the upĆ per level. The two ends of the belt should be approximately 6Ć9" (15Ć22 cm) past the left shaft (right shaft if right to left travel is required) on the upper level of the belt support.

Side Belt Loops

Direction of

Travel

FIGURE 2

2-1

Page 24

ASSEMBLY

4. Install the inner and outer master links as shown in FIGURE 3.

Master Link

Direction of

Travel

FIGURE 3

DIRECTION OF TRAVEL

7 holes

Burner Side

Slots

Closed

Unless otherwise specified, the conveyor travel is factory set for leftĆtoĆright operation when facing the drop down door. If a direction change is reĆ quired, the polarity of the drive motor must be reĆ versed. To change the polarity of the drive motor, disconnect the oven from the power source and inĆ terchange the black and white motor leads at the D.C. Controller Board located within the control box. If the polarity of the motor is changed to

rightĆtoĆleft belt travel, the conveyor belt must be installed from the left side of the oven inĆ stead of the right side.

NOTE: Reconfigure the air plates whenever the

conveyor belt direction of travel is changed. See FIGURE 4.

Slots

Closed

Air Hole

BlockĆoff

Slots

Closed

Air Hole

BlockĆoff

Front Of Oven

DIRECTION OF TRAVEL

Burner Side

Front Of Oven

FIGURE 4

7 holes

Slots

Closed

2-2

Page 25

MT3255 and MT3270

DRIVE CHAIN

1. Install the drive chain around the drive motor and then around the sprocket on the conveyor belt support.

2. Push the conveyor motor back to tighten the drive chain.

3. Lock the motor into position by tightening the four 1/4Ć20 hex head screws and dimples (washers on older models) between the conĆ veyor motor and the control box.

NOTE: Twin belt models have a double

sprocket, chain and motor.

END PLUGS

1. Install the upper and lower end plugs at both ends of the oven.

CRUMB PANS

1. Install the crumb pans under each end of the conveyor.

NOTE: On stacked ovens, either use perfoĆ

rated crumb pans or install the pans on the lower oven only.

WINDOW HANDLE

1. Install the window handle.

2-3

Page 26

CHAPTER 3

OPERATION

Page 27

MT3255 and MT3270

STANDARD CONTROL OPTIONS

U.E. TEMPERATURE CONTROLLER WITH OPEN LOOP DC DRIVE SYSTEM

1 53 42

COOK TIME

ON OFF

TEMPERATURE

CONVEYOR

FIGURE 1

CONTROL DESCRIPTION

1. COOK TIME DISPLAY - Displays the belt speed.

2. CONVEYOR ADJUSTMENT KNOB - Turn to adjust the conveyor speed.

3. TEMPERATURE CONTROL KNOB - Turn to set cook temperature.

4. HEAT LIGHT - Indicates the control is calling for heat.

5. HEAT SWITCH - Controls power to the burner.

6. BLOWER SWITCH - Controls power to the blowers.

7. CONVEYOR SWITCH - Controls power to the conveyor motor.

CONTROL OPERATION

1. Turn the manual gas valve to the OPEN posiĆ tion. This is only necessary on initial startĆup.

2. Turn the BLOWER SWITCH (6) to ON.

3. Push and turn the TEMPERATURE CONTROL KNOB (3) clockwise to the desired setting.

4. Turn the HEAT SWITCH (5) to ON. The burner purge timer will be energized. After approxiĆ mately thirty (30) seconds, a spark ignites the burner. Initial start may require longer due to air in the gas line.

ON OFF

HEAT

ON OFF

BLOWER

NOTE: If the oven fails to ignite after the thirty

(30) second purge, turn the HEAT SWITCH (5) to OFF and wait 5 minutes before turning back to ON.

5. Turn the CONVEYOR SWITCH (7) to ON. The conveyor belt starts to travel through the oven. This circuit is independent and can be turned on or off without affecting any other operaĆ tions. Adjust the conveyor speed as follows:

Turn the ADJUSTMENT KNOB (2) clockwise to increase speed, counterĆclockwise to deĆ crease speed. Turn the knobĆlock behind the control knob to hold the desired belt speed

6. Turn the BLOWER (6), CONVEYOR (7) and HEAT (8) SWITCHES to OFF. The Cool Down circuit is energized. The blower motor(s) conĆ tinue to run until the oven temperature is beĆ tween 135-170F (57-77C). The digital temperature display remains lit until the cool down circuit deĆenergizes.

The oven will hold these parameters daily and will require no further adjustments unless a different product is placed in the oven.

NOTE: Each oven contains different components

and must be adjusted individually.

3-1

Page 28

OPERATION

U.E. TEMPERATURE CONTROLLER WITH CLOSED LOOP DC DRIVE SYSTEM

1 532 4

COOK TIME

ON OFF

TEMPERATURE

CONVEYOR

FIGURE 2

CONTROL DESCRIPTION

1. COOK TIME DISPLAY - Displays the belt speed.

2. CONVEYOR ADJUSTMENT KEYS - Press to adjust the conveyor speed.

3. TEMPERATURE CONTROL KNOB - Turn to set cook temperature.

4. HEAT LIGHT - Indicates the control is calling for heat.

5. HEAT SWITCH - Controls power to the burner.

6. BLOWER SWITCH - Controls power to the blowers.

7. CONVEYOR SWITCH - Controls power to the conveyor motor.

CONTROL OPERATION

1. Turn the manual gas valve to the OPEN posiĆ tion. This is only necessary on initial startĆup.

2. Turn the BLOWER SWITCH (6) to ON.

3. Push and turn the TEMPERATURE CONTROL KNOB (3) clockwise to the desired setting.

4. Turn the HEAT SWITCH (5) to ON. The burner purge timer will be energized. After approxiĆ mately thirty (30) seconds, a spark ignites the

ON OFF

HEAT

ON OFF

BLOWER

burner. Initial start may require longer due to air in the gas line.

NOTE: If the oven fails to ignite after the thirty

(30) second purge, turn the HEAT SWITCH (5) to OFF and wait 5 minutes before turning back to ON.

Press the UP ARROW (2) to increase the conĆ veyor speed and the DOWN ARROW (2) to deĆ crease the conveyor speed.

The oven will hold these parameters daily and will require no further adjustments unless a different product is placed in the oven.

NOTE: Each oven contains different components

and must be adjusted individually.

3-2

Page 29

MT3255 and MT3270

ATHENA TEMPERATURE CONTROLLER WITH OPEN LOOP DC DRIVE SYSTEM

1 2

COOK TIME

ON OFF

ACTUAL SETPOINT HEAT

TEMPERATURE

CONVEYOR

FIGURE 3

CONTROL DESCRIPTION

1. COOK TIME DISPLAY - Gives the belt speed.

2. CONVEYOR ADJUSTMENT KNOB - Turn to adjust the conveyor speed.

3. ACTUAL TEMPERATURE KEY - Press to disĆ play the actual oven temperature.

4. ACTUAL TEMPERATURE LIGHT - When lit inĆ dicates the control is displaying the actual oven temperature.

5. SETPOINT LIGHT - When lit indicates control is displaying desired cook temperature.

6. HEAT LIGHT - When lit indicates that the conĆ trol is calling for heat.

7. UP and DOWN ARROW KEYS - Used to inĆ crease/decrease desired cook temperature.

8. HEAT SWITCH - Controls power to the burner.

9. BLOWER SWITCH - Controls power to the blowers.

10. CONVEYOR SWITCH - Controls power to the conveyor motor.

CONTROL OPERATION

1. Turn the manual gas valve to the OPEN posiĆ tion. This is only necessary on initial startĆup.

2. Turn the BLOWER SWITCH (9) to ON.

3. Press the UP or DOWN ARROW keys (7) to enĆ ter the desired cook temperature.

4. Turn the HEAT SWITCH (8) to ON.

83 4 5 7

ON OFF

HEAT

ON OFF

BLOWER

NOTE: If the oven fails to ignite after the thirty

(30) second purge, turn the blower switch OFF and wait 5 minutes before turning back ON.

5. Press the ACTUAL TEMPERATURE KEY (3). If the actual temperature matches the setpoint the oven is ready to cook.

NOTE: The display will flash until the actual

temperature is within the preset deviĆ ation alarm band. The default setting is  20F of the setpoint.

6. Turn the CONVEYOR SWITCH (10) to ON. The conveyor belt starts to move. Turn the CONĆ VEYOR ADJUSTMENT KNOB (2) clockwise to increase speed, counterĆclockwise to deĆ crease speed. Turn the knobĆlock behind the control knob to hold the desired belt speed

7. Turn the BLOWER (6), CONVEYOR (7) and HEAT (8) SWITCHES to OFF. The Cool Down circuit is energized. The blower motor(s) conĆ tinue to run until the oven temperature is beĆ tween 135-170F (57-77C). The digital temperature display remains lit until the cool down circuit deĆenergizes.

The oven will hold these parameters daily and will require no further adjustments unless a different product is placed in the oven.

NOTE: Each oven contains different components

and must be adjusted individually.

3-3

Page 30

OPERATION

ATHENA TEMPERATURE CONTROLLER WITH CLOSED LOOP DC DRIVE SYSTEM

COOK TIME

ON OFF

ACTUAL SETPOINT HEAT

TEMPERATURE

CONVEYOR

FIGURE 4

CONTROL DESCRIPTION

1. COOK TIME DISPLAY - Gives the belt speed.

2. ACTUAL TEMPERATURE KEY - Press to disĆ play the actual oven temperature.

3. CONVEYOR ADJUSTMENT KEYS - Press to adjust the conveyor speed.

4. ACTUAL TEMPERATURE LIGHT - When lit inĆ dicates the control is displaying the actual oven temperature.

5. SETPOINT LIGHT - When lit indicates control is displaying desired cook temperature.

6. HEAT LIGHT - When lit indicates that the conĆ trol is calling for heat.

7. UP and DOWN ARROW KEYS - Used to inĆ crease/decrease desired cook temperature.

8. HEAT SWITCH - Controls power to the burner.

9. BLOWER SWITCH - Controls power to the blowers.

10. CONVEYOR SWITCH - Controls power to the conveyor motor.

11. CONVEYOR ADJUSTMENT KNOB - Turn to adjust the conveyor speed.

CONTROL OPERATION

1. Turn the manual gas valve to the OPEN posiĆ tion. This is only necessary on initial startĆup.

2. Turn the BLOWER SWITCH (9) to ON.

83 4 5 7

ON OFF

HEAT

ON OFF

BLOWER

4. Turn the HEAT SWITCH (8) to ON.

NOTE: If the oven fails to ignite after the thirty

(30) second purge, turn the blower switch OFF and wait 5 minutes before turning back ON.

5. Press the ACTUAL TEMPERATURE KEY (3). If the actual temperature matches the setpoint the oven is ready to cook.

NOTE: The display will flash until the actual

temperature is within the preset deviĆ ation alarm band. The default setting is  20F of the setpoint.

6. Press the UP ARROW (2) to increase the conĆ veyor speed and the DOWN ARROW (2) deĆ creases the conveyor speed.

The oven will hold these parameters daily and will require no further adjustments unless a different product is placed in the oven.

NOTE: Each oven contains different components

and must be adjusted individually.

3. Press the UP or DOWN ARROW keys (7) to enĆ ter the desired cook temperature.

3-4

Page 31

MT3255 and MT3270

COMPUTER CONTROLLER

45678

FIGURE 5

CONTROL DESCRIPTION

1. DIGITAL DISPLAY - Displays the time, temĆ perature and controller related information.

2. OVEN ON/OFF - Controls power to the oven.

3. NUMERIC KEYS - Used to enter numerical data in the programming mode.

4. CLEAR KEY - Used to clear the display if an error is made in the programming mode.

5. SET TEMP KEY - Used to view or program the temperature setpoint.

6. ACT TEMP KEY - Used to view the current oven temperature.

7. TIME KEY - Used to view or program the cook time.

8. PROG/ENTER KEY - Used to enter and exit the programming mode. Also used to lock in programmed settings.

9. STATUS LAMPS - When lit indicate that the fan or burners are operating.

This oven, supplied with remote control, is equipped with an emergency shut down switch. Should you need to stop the belt, fans, or heat press the emergency switch.

CONTROL OPERATION

To turn the oven on:

1. Press and hold the ON/OFF key (2). The disĆ play reads OFF when the oven is idle.

2. The display flashes WAIT  LOW  SET  TIME.

3. The FAN and HEAT status lamps (9) light. The fans begin to run. The heat rises to the proĆ grammed temperature. The conveyor belt travels at the programmed speed.

To view the cook time setting:

1. Press the TIME key (7). The LED on the key lights and the display flashes SET  TIME.

To display the actual oven temperature:

1. Press the ACT TEMP key (6). The LED on the key lights and the display reads ACTUAL  F.

To view the temperature set point:

1. Press the SET TEMP key (5). The LED on the key lights and the display flashes SET  TEMP

 F.

To turn the oven off:

1. Press the ON/OFF key (2). The blower moĆ tor(s) continue to run regardless of the controlĆ ler status until the temperature drops below 180F (82C).

Do not use the emergency switch as a GENERAL on/off switch!

3-5

Page 32

OPERATION

PROGRAMMING PROCEDURES

Programming the Cook Time:

1. Press the PROGRAM/ENTER key (8).

2. Press the TIME key (7). The display reads

PROGĆ?  SET  TIMEĆ?  _ _ _ _.

3. Use the NUMERIC keys (3) to enter the desired cook time. The display will read the numbers as they are entered. If an error is made, press the CLEAR key (4) and reĆenter the number.

4. Press the PROGRAM/ENTER key (8) a second time to lockĆin the new time. The new cook time will be stored in the computer's memory.

Programming the Temperature:

1. Press the PROGRAM/ENTER key (8).

2. Press the SET TEMP key (5). The display reads

PROGĆ?  SET  TEMPĆ?  _ _ _ _F.

3. Use the NUMERIC keys (3) to enter the desired temperature set point. The control displays the numbers as they are entered. If an error is made, press the CLEAR key (4) and reĆenter the number.

4. Press the PROGRAM/ENTER key (8) a second time to lockĆin the new temperature. The new temperature setpoint will be stored in the comĆ puter's memory.

Operation at the Programmed Settings:

DISPLAY INFORMATION

 WAIT  LOW - indicates that the present oven

temperature is lower than the set point temperĆ ature. When the oven reaches the set point temperature the display changes to READY.

 READY - indicates that the oven is ready to acĆ

cept product.

 SET  TEMP  mmss - indicates the current

cook time setting.

 HIGH  TIME - indicates that the temperature

is well above the set point. This usually occurs when moving from a higher āto a lower temperaĆ ture. Wait until the display reads ready before loading product.

 HIGH  TEMP  LIMIT - indicates that the oven

temperature exceeds the high limit from the 2nd level program. The Over Temperature Alarm buzzer will sound. Shut the oven off and wait for the unit to cool down.

 HIGH  TEMP  PANEL - indicates that the conĆ

trol area reaches an excessive temperature. Shut the oven off and wait for the unit to cool down. Error code generally means loose ground wire.

 PROBE  OPEN  PROBE  SHORT - indicates

that the temperature sensor has failed. The Alarm buzzer sounds. Shut the oven off and contact a service representative.

1. Press and hold the ON/OFF key (2).

2. The FAN and HEAT status lamps (9) light. The fans begin to run. The heat rises to the temperĆ ature setting stored in the computer's memory. The conveyor belt begins to travel at the timed speed stored in memory.

3. The display will flash WAIT  LOW  SET  TIME until the programmed bake temperature is reached. The HEAT lamp (9) will remain lit until the oven reaches the temperature set point.

4. The display reads READY and the HEAT lamp (9) goes out.

5. The oven is now ready to accept product.

6. Press and hold the ON/OFF key (2) to turn the oven off. The fans continue to run while the oven cools to a safe temperature.

3-6

Page 33

MT3255 and MT3270

SEQUENCE OF OPERATION

NOTE: The following instructions represent the most common configurations. For questions regarding othĆ

er options call the Blodgett Service Department at (800)331Ć5842.

MTĆ70ĆPH DOMESTIC - M2468 REV E

NOTE: The following is also applicable to the

MT3255 with 3 blower motors.

COMPONENT REFERENCE

NOTE: Refer to FIGURE 6 page 3-21 for compoĆ

nent locations.

1. BLOWER SWITCH (M0153)

2. TEMPERATURE CONTROLLER (M3149)

3. SPST RELAY (16988)

4. MOTOR CONTACTORS A & B (M0708)

5. CONVECTION FANS (Clockwise - M4224, CounterĆclockwise - M4225)

6. THERMOCOUPLES (Dual lead - M3151, Single - M3152)

7. HI/LO LIMIT BOARD (M3150)

8. HEAT SWITCH (M0152)

9. SPDT THERMAL SWITCH (M2453)

10. SINGLE SOLENOID GAS VALVE (20287)

11. PRESSURE SWITCH (M0595)

12. 220/24 VAC TRANSFORMER (M2381)

13. PURGE RELAY (M2385)

14. COMBUSTION MOTOR (M0767)

15. CENTRIFUGAL SWITCH

16. IGNITION CONTROL (M1054)

17. PILOT VALVE (LP - 22190, Natural - M5495)

18. MAIN VALVE (LP - 22190, Natural - M5495)

19. SPDT THERMAL SWITCH (M2453)

20. COOLING FANS (4Ć1/2" - M2469, 3Ć1/5" - 21134)

21. MOMENTARY SWITCH (M2497)

22. 120 VOLT RELAY (16241)

23. BUZZER

24. CONVEYOR SWITCH (M0152)

25. 10kW POTENTIOMETER (M3145)

26. #10 PICKUP (M3147)

27. TIME DISPLAY (M3146)

28. D.C. MOTOR (M2378)

29. D.C. SPEED CONTROL BOARD (M2379)

30. INDICATOR LIGHT (M0791)

OPERATION

1. Turn the blower switch (1) to ON. The N.O. conĆ tacts close, the N.C. contacts open. 115 VAC runs to L1 of the temperature controller (2), both coils of the motor contactors (4) and terĆ minal #7 of the hi/lo limit board (7). Terminal #7 is an output. It remains powered after the oven is shut down to keep the convection fans (5) operating until the unit reaches 135-170F (57-77C) as sensed by the thermocouples (6).

NOTE: Two thermocouples are located beĆ

tween the middle convection fans in the rear of the oven. One thermocouple provides DC millivolts to the Hi/Lo limit board. The other provides DC milivolts to the temperature controller. Check thermocouples with a millivolt meter.

2. Turn the heat switch (8) to ON. Power goes to the common terminal of the temperature conĆ troller (2) and terminal #5 of the Hi/Lo limit board (7). A switch is made between terminals #5 and #6 of the Hi/Lo limit board. This switch opens if the oven cavity temperature exceeds 600F (316C). Terminal #6 of the Hi/Lo board is an output and sends power to a pressure switch (11). The switch reacts from a vacuum created by the convection fans. If the switch is closed, power runs to the primary side of a 115/24 VAC transformer (12) and a contact on the purge relay (13).

NOTE: These components are located in a

box mounted on top of the combustion motor.

When 24 VAC is applied to this relay, the conĆ tacts close sending 115 VAC to start the comĆ bustion motor (14). When the combustion moĆ tor reaches full speed, a centrifugal switch (15) closes sending 24 VAC to the ignition module (16). After the module's self diagnostics are complete, the pilot valve (17) opens. When a proof of flame is established, the main burner valve (18) opens.

3. Output from the temperature controller (2) goes from N.O. terminal to the common termiĆ

3-7

Page 34

OPERATION

nal of a SPDT thermal switch (9). The switch toggles if the temperature passing its face exĆ ceeds the rating on the back of the switch.

NOTE: The switch is located in the front conĆ

trol compartment. It protects the other components from hi ambient heat.

If this switch is cold, it should be made beĆ tween common and N.C. terminals sending power to the single solenoid gas valve (10).

4. When power is applied to the coils of both moĆ tor contactors (4) the contacts close sending power to the four convection fans (5) located in the back of the oven. Power is also applied to the coil of the SPST relay (3).

NOTE: The SPST relay acts as a hood interĆ

lock and is sometimes used as a means of starting the hood.

5. The oven has six cooling fans (19). Two on the front control panel keep the panel below 140F (60C). The fan's airflow is from left to right for flow through ventilation. The other four, in the rear of the oven, keep the convection fans from overheating. The cooling fans start when the motor contactor powers up and closes beĆ tween terminals #13 and #14. Power goes to the N.C. terminal of a SPDT thermal switch (18). The switch toggles if the temperature passing its face exceeds the rating on the back of the switch and may start the fans even if the oven is off. If this switch is cold, it should be made between common and N.C. terminals sending power to the cooling fans.

6. The conveyor is driven by an open loop D.C. control system consisting of a conveyor switch (23), time display (26), 10kW potentiometer (24), D.C. speed control board (28), 130 VDC motor (27) and #10 Hall effect pickup (25). ReĆ fer to page 5-1 for pickup troubleshooting. AfĆ ter the conveyor switch is turned on, the time display illuminates. The D.C. control board powers up. The output voltage measured on terminals A1 and A2 of the board to the motor varies from 20 to130 VDC based on the posiĆ tion of the potentiometer. The speed of the moĆ tor should also vary. The time display varies deĆ pending on the speed of the Hall effect pickup. The pickup sends an R.P.M value to the disĆ play. The display converts this value to minĆ utes:seconds.

NOTE: This type of system does not sense the

weight of the product and will slow down slightly if the belt is fully loaded.

7. If the thermal switch (9) in the control panel toggles due to high heat, the single solenoid valve (10) closes. Power runs through a moĆ mentary switch (20) to the coil of a 115 volt relay (21). When this relay closes, a buzzer (22) sounds and an indicator lamp (29) lights, indiĆ cating a control compartment high temperaĆ ture. Pressing the momentary switch disenĆ gages the relay, silencing the buzzer. The indicator lamp remains lit until the temperature drops 20F across the face of the thermal switch, allowing the burner to refire.

NOTE: The switch is located on the ceiling of

the convection fan compartment.

3-8

Page 35

MT3255 and MT3270

MTĆ70ĆPH GENERAL EXPORT - M2501 REV D

NOTE: The following is also applicable to the

MT3255 with 3 blower motors.

COMPONENT REFERENCE

NOTE: Refer to FIGURE 7 page 3-22 for compoĆ

nent locations.

1. BLOWER SWITCH (M0153)

2. TEMPERATURE CONTROLLER (M3155)

3. SPST RELAY (16988)

4. MOTOR CONTACTORS A & B (M0708)

5. CONVECTION FANS (Clockwise - M4597, CounterĆclockwise - M4598)

6. THERMOCOUPLES (Dual lead - M3151, Single - M3152)

7. HI/LO LIMIT BOARD (M3150)

8. HEAT SWITCH (M0152)

9. SPDT THERMAL SWITCH (M2453)

10. SINGLE SOLENOID GAS VALVE (M2245)

11. PRESSURE SWITCH (M0595)

12. 220/24 VAC TRANSFORMER (M2384)

13. PURGE RELAY (M2385)

14. COMBUSTION MOTOR (M2276)

15. IGNITION CONTROL (M1054)

16. PILOT VALVE (LP - 22190, Natural - M5495)

17. MAIN VALVE (LP - 22190, Natural - M5495)

18. SPDT THERMAL SWITCH (M2453)

19. COOLING FANS (4Ć1/2" - 23034, 3Ć1/5" - 21430)

20. MOMENTARY SWITCH (M2497)

21. 240 VOLT RELAY (90250)

22. BUZZER

23. CONVEYOR SWITCH (M0152)

24. 10kW POTENTIOMETER (M3145)

25. #10 PICKUP (M3147)

26. TIME DISPLAY (M3154)

27. D.C. MOTOR (M3128)

28. D.C. SPEED CONTROL BOARD (M3153)

29. INDICATOR LIGHT (16037)

OPERATION

1. Turn the blower switch (1) to ON. The N.O. conĆ tacts close, the N.C. contacts open. 220 or 240 VAC runs to terminal #3 of the temperature controller (2), both coils of the motor contacĆ tors (4) and terminal #7 of the hi/lo limit board (7). Terminal #7 is an output. It remains powĆ ered after the oven is shut down to keep the convection fans (5) operating until the unit reaches 135-170F (57-77C) as sensed by the thermocouples (6).

NOTE: Two thermocouples are located beĆ

2. Turn the heat switch (8) to ON. Power goes to terminal #6 of the temperature controller (2) and terminal #5 of the Hi/Lo limit board (7). A switch is made between terminals #5 and #6 of the Hi/Lo limit board. This switch opens if the oven cavity temperature exceeds 600F (316C). Terminal #6 of the Hi/Lo board is an output and sends power to a pressure switch (11). The switch reacts from a vacuum created by the convection fans. If the switch is closed, power runs to the primary side of a 220/24 VAC transformer (12) and a contact on the purge relay (13).

NOTE: These components are located in a

box mounted on top of the combustion motor.

When 24 VAC is applied to this relay, the conĆ tacts close sending 220 VAC to start the comĆ bustion motor (14). The relay also sends powĆ er to terminal #2 of the ignition control system (15). After the module's self diagnostics are complete, the pilot valve (16) opens. When a proof of flame is established, the main burner valve (17) opens.

3. Output from the temperature controller (2) goes from terminal #4 to the common terminal of a SPDT thermal switch (9). The switch toggles if the temperature passing its face exĆ ceeds the rating on the back of the switch.

3-9

Page 36

OPERATION

NOTE: The switch is located in the front conĆ

trol compartment. It protects the other components from hi ambient heat.

If this switch is cold, it should be made beĆ tween common and N.C. terminals sending power to the single solenoid gas valve (10).

NOTE: The SPST relay acts as a hood interĆ

lock and is sometimes used as a means of starting the hood.

5. The oven has six cooling fans (19). Two on the front control panel keep the panel below 140F (60C). The fan's airflow is from left to right for flow through ventilation. The other four, in the rear of the oven, keep the convection fans from overheating. The cooling fans start when the motor contactor powers up and closes beĆ tween terminals #5 and #6. Power goes to the N.C. terminal of a SPDT thermal switch (18). The switch toggles if the temperature passing its face exceeds the rating on the back of the switch and may start the fans even if the oven is off. If this switch is cold, it should be made between common and N.C. terminals sending power to the cooling fans.

NOTE: The switch is located on the ceiling of

the convection fan compartment.

6. The conveyor is driven by an open loop D.C. control system consisting of a conveyor switch (23), time display (26), potentiometer (24), D.C. speed control board (28), 180 VDC motor (27) and #10 Hall effect pickup (25). Refer to page 5-1 for pickup troubleshooting. After the conveyor switch is turned on, the time display illuminates. The D.C. control board powers up. The output voltage measured on the A1 and A2 of the board to the motor varies from 20 to180 VDC based on the position of the potentiomeĆ ter. The speed of the motor should also vary. The time display varies depending on the speed of the Hall effect pickup. The pickup sends an R.P.M value to the display. The disĆ play converts this value to minutes:seconds.

NOTE: This type of system does not sense the

weight of the product and will slow down slightly if the belt is fully loaded.

7. If the thermal switch (9) in the control panel toggles due to high heat, the single solenoid valve (10) closes. Power runs through a moĆ mentary switch (20) to the coil of a 240 volt relay (21). When this relay closes, a buzzer (22) sounds and an indicator lamp (29) lights, indiĆ cating a control compartment high temperaĆ ture. Pressing the momentary switch disenĆ gages the relay, silencing the buzzer. The indicator lamp remains lit until the temperature drops 20F across the face of the thermal switch, allowing the burner to refire.

3-10

Page 37

MT3255 and MT3270

MT3270 WITH STANDARD CONTROLS - 21575 REV E

NOTE: The following is also applicable to the

MT3255 with 3 blower motors.

COMPONENT REFERENCE

NOTE: Refer to FIGURE 8 page 3-23 for compoĆ

nent locations.

1. BLOWER SWITCH (M0153)

2. TEMPERATURE CONTROLLER (M3149)

3. MOTOR CONTACTOR A & B (M0708)

4. THERMOCOUPLES (Dual lead - M3151, Single - M3152)

5. HI/LO LIMIT BOARD (M3150)

6. CONVECTION FANS (Clockwise - M4224, CounterĆclockwise - M4225)

7. HEAT SWITCH (M0152)

8. COMBUSTION MOTOR (22132)

9. PRESSURE SWITCH (M0595)

10. 110/24 VAC TRANSFORMER (M2381)

11. PURGE RELAY (M2382)

12. CENTRIFUGAL SWITCH

13. IGNITION MODULE (M1054)

14. PILOT VALVE (LP - 22190, Natural - M5495)

15. MAIN VALVE (LP - 22190, Natural - M5495)

16. SPST THERMAL SWITCH (M1362)

17. SINGLE SOLENOID GAS VALVE (20287)

18. COOLING FANS (4Ć1/2" - M2469, 3Ć1/5" - 21134)

19. SPST THERMAL SWITCH (M0635)

20. CONVEYOR SWITCH (M0152)

21. TIME DISPLAY (M3146)

22. 10KW POTENTIOMETER (M3145)

23. D.C. SPEED CONTROL BOARD (M2379)

24. 130 VDC MOTOR (M2378)

25. #10 PICK UP (M3147)

OPERATION

1. Turn the blower switch (1) to ON. The N.O. conĆ tacts close, the N.C. contacts open. 115 VAC runs to terminal #1 of the temperature controlĆ ler (2), both coils of the motor contactors (3) and terminal #7 of the hi/lo limit board (5). TerĆ minal #7 is an output. It remains powered after the oven is shut down to keep the convection fans (6) operating until the unit reaches 135-170F (57-77C) as sensed by the therĆ mocouples (4).

NOTE: Two thermocouples are located beĆ

2. Turn the heat switch (7) to ON. Power goes to terminal #6 of the temperature controller (2) and terminal #5 of the Hi/Lo limit board (5). A circuit is made between terminals #5 and #6 of the Hi/Lo limit board. This switch opens if the oven cavity temperature exceeds 600F (316C) as sensed by the thermocouples. TerĆ minal #6 of the Hi/Lo board is an output and sends power to a pressure switch (9). The switch reacts from a vacuum created by the convection fans. If the switch is closed, power runs to the primary side of a 115/24 VAC transĆ former (10) and a contact on the purge relay (11).

NOTE: These components are located in a

box mounted on top of the combustion motor.

When 24 VAC is applied to this relay, the conĆ tacts close sending 115 VAC to start the comĆ bustion motor (8). When the combustion moĆ tor reaches full speed, a centrifugal switch (12) closes sending 24 VAC to the ignition module (13). After the module's self diagnostics are complete, the pilot valve (14) opens. When a proof of flame is established, the main burner valve (15) opens.

3. Output from the temperature controller (2) goes from terminal #4 to a terminal of a SPDT thermal switch (16). The switch toggles if the temperature passing its face exceeds the ratĆ ing on the back of the switch.

3-11

Page 38

OPERATION

NOTE: The switch is located in the front conĆ

trol compartment. It protects the other components from hi ambient heat.

If this switch is cold, it should be closed sendĆ ing power to the single solenoid gas valve (17).

4. When power is applied to the coils of both moĆ tor contactors (3) the contacts close sending power to the four convection fans (6) located in the back of the oven.

NOTE: The switch is located on the ceiling of

the convection fan compartment.

6. The conveyor is driven by an open loop D.C. control system consisting of a conveyor switch (20), time display (21), 10kW potentiometer (22), D.C. speed control board (23), 130 VDC motor (24) and #10 Hall effect pickup (25). ReĆ fer to page 5-1 for pickup troubleshooting. AfĆ ter the conveyor switch is turned on, the time display illuminates. The D.C. control board powers up. The output voltage measured at A1 and A2 of the board to the motor varies from 20 to130 VDC based on the position of the potenĆ tiometer. The speed of the motor should also vary. The time display varies depending on the speed of the Hall effect pickup. The pickup sends an R.P.M value to the display. The disĆ play converts this value to minutes:seconds.

NOTE: This type of system does not sense the

weight of the product and will slow down slightly if the belt is fully loaded.

3-12

Page 39

MT3255 and MT3270

MT3270 TWIN BELT WITH REMOTE CONTROLS - M4410 REV A

COMPONENT REFERENCE

NOTE: Refer to FIGURE 9 page 3-24 for compoĆ

nent locations.

1. COMPUTER (FW525)

2. BLOWER RELAY (22672)

3. MAIN CONTROL RELAY (22672)

4. BURNER VALVE RELAY (22672)

5. SPEED CONTROL BOARDS A & B (M2379)

6. SPST THERMAL SWITCH (M1362)

7. MANUAL RESETABLE HI LIMIT (M3295)

8. PRESSURE SWITCH (M0595)

9. 115/24 VAC TRANSFORMER (M2381)

10. PURGE RELAY (M2382)

11. COMBUSTION MOTOR (22132)

12. CENTRIFUGAL SWITCH

13. IGNITION CONTROL SYSTEM (M1054)

14. PILOT VALVE (LP - 22190, Natural - M5495)

15. MAIN VALVE (LP - 22190, Natural - M5495)

16. MOTOR CONTACTOR (M0708)

17. CONVECTION FANS (Clockwise - M4224, CounterĆclockwise - M4225)

18. COOLING FANS (4Ć1/2" - M2469, 3Ć1/5" - 21134)

19. SPDT THERMAL SWITCH (M2453)

20. D.C. MOTOR (M2378)

21. RTD PROBE (M7427)

22. EMERGENCY SHUTDOWN SWITCH (M0152)

OPERATION

1. Apply power to the oven. Program the time and temperature into the computer (1). The burner valve relay (4), blower relay (2) and main conĆ trol relay (3) energize powering up the oven.

2. The main control relay (3) sends power to the front and rear speed control boards (5) and the SPST thermal switch (6). The switch toggles if the temperature passing its face exceeds the rating on the back of the switch. If the thermal switch is closed, power is supplied to the manual reset high limit switch (7). The high limĆ it switch is a bulb and capillary style switch. It reacts when the oven cavity temperature exĆ ceeds the high limit programmed into the cooking computer.

If the high limit switch is closed power flows to the convection fan pressure switch (8). The switch reacts from a vacuum created by the convection fans.

If the pressure switch is closed, power runs to the primary side of a 115/24 VAC transformer (9) and a contact on the purge relay (10). These components are located in a box mounted on top of the combustion motor.

When 24 VAC are applied to the purge relay, the contacts close sending 115 VAC to start the combustion motor (11). When the combusĆ tion motor reaches full speed, a centrifugal switch (12) closes sending 24 VAC to the igniĆ tion module (13). After the module's self diagĆ nostics are complete, the pilot valve (14) opens. When a proof of flame is established, the ignition control module (13) sends 24 VAC to terminal #6 of the burner valve relay (4). If this relay is closed on a call for heat, as sensed by an RTD probe, a circuit is completed beĆ tween terminal #6 and #5 sending 24 VAC to the main valve (15).

NOTE: The RTD probe is located between the

two middle convection fans in the rear of the oven. Check the probe with an ohm meter.

3. The blower relay (2) sends 115 volts to the coil of the motor contactor (16) starting the four convection fans (18) in the rear of the oven. This contactor also supplies power to the N.C. terminal of a SPDT thermal switch (19). The switch toggles if the temperature passing its

3-13

Page 40

OPERATION

face exceeds the rating on the back of the switch and may start the fans even if the oven is off. If this switch is cold, it should be made between common and N.C. terminals sending power to the cooling fans (18).

NOTE: The SPDT thermal switch is located in

the ceiling of the convection fan compartment.

4. The conveyors are driven by an open loop DC control system consisting of two DC speed control boards (5), two 130 VDC motors (20) and the DAC located in the cooking computer (1). If a time is programmed into the cooking computer, a voltage ranging between .47 and

4.7 is applied to the DC speed control boards. The output voltage measured at A1 and A2 of the boards to the motors varies from 20 to130 VDC based on the DAC voltage applied to the

board or the time programmed into the comĆ puter.

NOTE: The DAC receives 20 VDC from the

speed control boards. The DAC reĆ turns a portion of the voltage (between .47 and 4.7 VDC). The amount of voltĆ age is dependent on the time proĆ grammed into the computer.

NOTE: This type of system does not sense the

weight of the product and will slow down slightly if the belt is fully loaded.

NOTE: This oven, supplied with remote conĆ

trol, is equipped with an emergency shut down switch. Should you need to stop the belt, fans, or heat press the emergency switch. Do not use the

emergency switch as a GENERAL on/off switch!

3-14

Page 41

MT3255 and MT3270

MT3270 WITH CLOSED LOOP - M4206 REV B

NOTE: The following is also applicable to the

MT3255 with 3 blower motors.

COMPONENT REFERENCE

NOTE: Refer to FIGURE 10 page 3-25 for compoĆ

nent locations.

1. BLOWER SWITCH (M0153)

2. TEMPERATURE CONTROL (M3149)

3. MOTOR CONTACTORS A & B (M0708)

4. HI/LO LIMIT BOARD (M3150)

5. CONVECTION FANS (Clockwise - M4224, CounterĆclockwise - M4225)

6. THERMOCOUPLES (Dual lead - M3151, Single - M3152)

7. HEAT SWITCH (M0152)

8. COMBUSTION MOTOR (22132)

9. PRESSURE SWITCH (M0595)

10. 115/24 TRANSFORMER (M2381)

11. PURGE RELAY (M2382)

12. CENTRIFUGAL SWITCH

13. IGNITION CONTROL MODULE (M1054)

14. PILOT VALVE (LP - 22190, Natural - M5495)

15. MAIN VALVE (LP - 22190, Natural - M5495)

16. SPST THERMAL SWITCH (M1362)

17. SINGLE SOLENOID GAS VALVE (20287)

18. COOLING FANS (4Ć1/2" - M2469, 3Ć1/5" - 21134)

19. SPDT THERMAL SWITCH (M2453)

20. CONVEYOR SWITCH (M0152)

21. D.C. MOTOR (M2378)

22. TIME DISPLAY/MOTOR DRIVE (M3393)

23. #2 HALL EFFECT PICKUP (M0984)

OPERATION

1. Turn the blower switch (1) to ON. The N.O. conĆ tacts close, the N.C. contacts open. 115 VAC runs to terminal #1 of the temperature controlĆ ler (2), both coils of the motor contactors (3) and terminal #7 of the hi/lo limit board (4). TerĆ minal #7 is an output. It remains powered after the oven is shut down to keep the convection fans (5) operating until the unit reaches 135-170F (57-77C) as sensed by the therĆ mocouples (6).

NOTE: Two thermocouples are located beĆ

2. Turn the heat switch (7) to ON. Power goes to terminal #6 of the temperature controller (2) and terminal #5 of the Hi/Lo limit board (4). A circuit is made between terminals #5 and #6 of the Hi/Lo limit board. This switch opens if the oven cavity temperature exceeds 600F (316C) as sensed by the thermocouples. TerĆ minal #6 of the Hi/Lo board is an output and sends power to a pressure switch (9). The switch reacts from a vacuum created by the convection fans. If the switch is closed, power runs to the primary side of a 115/24 VAC transĆ former (10) and a contact on the purge relay (11).

NOTE: These components are located in a

box mounted on top of the combustion motor.

3. Output from the temperature controller (2) goes from terminal #4 to a terminal of a SPST thermal switch (16). The switch toggles if the temperature passing its face exceeds the ratĆ ing on the back of the switch.

3-15

Page 42

OPERATION

NOTE: The switch is located in the front conĆ

trol compartment. It protects the other components from hi ambient heat.

If this switch is cold, it should be closed sendĆ ing power to the single solenoid gas valve (17).

4. When power is applied to the coils of both moĆ tor contactors (3) the contacts close sending power to the four convection fans (5) located in the back of the oven.

5. The oven has six cooling fans (18). Two on the front control panel keep the panel below 140F (60C). The fan's airflow is from left to right for flow through ventilation. The other four, in the rear of the oven, keep the convection fans from overheating. The cooling fans start when the motor contactor powers up and closes beĆ tween terminals #13 and #14. Power goes to the N.C. terminal of a SPDT thermal switch (19). The switch toggles if the temperature passing its face exceeds the rating on the back of the switch and may start the fans even if the oven is off. If this switch is cold, it should be made between common and N.C. terminals sending power to the cooling fans.

6. The conveyor belt is driven by a closed loop D.C. drive system consisting of a conveyor switch (20), 130 VDC motor (21), time display and motor drive (22) and a #2 Hall effect pickĆ up (23). Refer to page 5-1 for pickup troubleĆ shooting. The motor speed varies based on the time programmed into the digital time disĆ play. To slow the belt down, press the down arĆ row key. To increase belt speed, press the up arrow key.

NOTE: When this component is replaced it

must be reprogrammed for the apĆ propriate tunnel length. Reference Calibration section page 4-4.

NOTE: This system senses the weight of the

product and compensates by increasĆ ing the voltage output.

NOTE: The switch is located on the ceiling of

the convection fan compartment.

3-16

Page 43

MT3255 and MT3270

MT3255E - M4289 REV B

COMPONENT REFERENCE

NOTE: Refer to FIGURE 11 page 3-26 for compoĆ

nent locations.

1. BLOWER SWITCH (M0153)

2. TEMPERATURE CONTROLLER (M3155)

3. MOTOR CONTACTORS (M0708)

4. HI/LO LIMIT BOARD (M3150)

5. CONVECTION FANS (Clockwise - M4597, CounterĆclockwise - M4598)

6. THERMOCOUPLES (Dual lead - M3151, Single - M3152)

7. HEAT SWITCH (M0152)

8. SPST THERMAL SWITCH (M1362)

9. ELEMENT CONTACTORS (M2247)

10. HEATING ELEMENTS (220 - M5282, 240 - M5281)

11. COOLING FANS (4Ć1/2" - 23034, 3Ć1/2" - 21430)

12. SPDT THERMAL SWITCH (M2453)

13. CONVEYOR SWITCH (M0152)

14. D.C. MOTOR (M2378)

15. TIME DISPLAY/MOTOR DRIVE (M3393)

16. #2 HALL EFFECT PICKUP (M0984)

OPERATION

1. Turn the blower switch (1) to ON. The N.O. conĆ tacts close, the N.C. contacts open. 115 VAC runs to L1 of the temperature controller (2), both coils of the motor contactors (3) and terĆ minal #7 of the hi/lo limit board (4). Terminal #7 is an output. It remains powered after the oven is shut down to keep the convection fans (5) operating until the unit reaches 135-170F (57-77C) as sensed by the thermocouples (6).

NOTE: Two thermocouples are located beĆ

tween two of the convection fans in the rear of the oven. One thermocouple provides DC millivolts to the Hi/Lo limit board. The other provides DC milivolts to the temperature controller. Check thermocouples with a millivolt meter.

2. Turn the heat switch (7) to ON. Power goes to the N.O. terminal of the temperature controller (2). On a call for heat the temperature controlĆ ler closes a switch between the N.O. and comĆ mon terminals. Power is sent to one side of a SPST thermal switch (8). The switch toggles if the temperature passing its face exceeds the rating on the back of the switch.

NOTE: The switch is located in the front conĆ

trol compartment. It protects the other components from hi ambient heat.

If this switch is cold it should be closed, sendĆ ing power to terminal #5 of the hi/lo limit board. A switch is made between terminals #5 and #6 of the Hi/Lo limit board. This switch opens if the oven cavity temperature exceeds 600F (316C). Terminal #6 of the Hi/Lo board is an output and sends power to the coil of the eleĆ ment contactor. When the element contactor closes it sends power to the heating elements.

3. The oven has six cooling fans (11). Two on the front control panel keep the panel below 140F (60C). The fan's airflow is from left to right for flow through ventilation. The other four, in the rear of the oven, keep the convection fans (5) from overheating. The cooling fans start when the motor contactor powers up and closes beĆ tween terminals #5 and #6. Power goes to the N.C. terminal of a SPDT thermal switch (12). The switch toggles if the temperature passing its face exceeds the rating on the back of the

3-17

Page 44

OPERATION

switch and may start the fans even if the oven is off. If this switch is cold, it should be made between common and N.C. terminals sending power to the cooling fans.

NOTE: The switch is located on the ceiling of

the convection fan compartment.

4. The conveyor belt is driven by a closed loop D.C. drive system consisting of a conveyor switch (13), 130 VDC motor (14), time display and motor drive (15) and a #2 Hall effect pickĆ up (16). Refer to page 5-1 for pickup troubleĆ shooting. The motor speed varies based on

the time programmed into the digital time disĆ play. To slow the belt down, press the down arĆ row key. To increase belt speed, press the up arrow key.

NOTE: When this component is replaced it

must be reprogrammed for the apĆ propriate tunnel length. Reference Calibration section page 4-4.

NOTE: This system senses the weight of the

product and compensates by increasĆ ing the voltage output.

3-18

Page 45

MT3255 and MT3270

MT3270 CE - M8296 REV A

NOTE: The following is also applicable to the

MT3255 with 3 blower motors.

COMPONENT REFERENCE

NOTE: Refer to FIGURE 12 page 3-27 for compoĆ

nent locations.

1. BLOWER SWITCH (M0153)

2. TEMPERATURE CONTROLLER (M3155)

3. MOTOR CONTACTOR (M2247)

4. SPST RELAY/HOOD INTERLOCK(16998)

5. HI/LO LIMIT BOARD (M3150)

6. CONVECTION FANS (Clockwise - M4597, CounterĆclockwise - M4598)

7. THERMOCOUPLES (Dual lead - M3151, Single - M3152)

8. HEAT SWITCH (M0152)

9. CONVECTION PRESSURE SWITCH (M0595)

10. COMBUSTION MOTOR (M2386)

11. BURNER PRESSURE SWITCH (M3330)

12. TPDT RELAY/LATCHING RELAY (M6519)

13. 10 SECOND PURGE TIMER (M3173)

14. SPST RELAY (16775)

15. SPDT THERMAL SWITCH (M2453)

16. IGNITION CONTROL MODULE/ LANDIS & GYR (M3168)

17. 2 SECOND PURGE TIMER (M3172)

18. PILOT VALVE (LP - M6001, Natural - M6000)

19. MAIN VALVE (LP - M6001, Natural - M6000)

20. IGNITION ALARM LIGHT (16037)

21. COOLING FANS (4Ć1/2" - 23034, 3Ć1/2" - 21430)

22. SPDT THERMAL SWITCH (M2453)

23. CONVEYOR SWITCH (M0152)

24. TIME DISPLAY (M3154)

25. 10KW POTENTIOMETER (M3145)

26. D.C. SPEED CONTROL BOARD (M3153)

27. 180 VDC MOTOR (M3128)

28. #10 HALL EFFECT PICKUP (M3147)

29. MOMENTARY SWITCH (M2497)

30. BUZZER

31. INDICATOR LAMP (16037)

32. TPDT RELAY (90250)

OPERATION

1. Turn the blower switch (1) to ON. The N.O. conĆ tacts close, the N.C. contacts open. 220 or 240 VAC runs to terminal #3 of the temperature controller (2), both coils of the motor contacĆ tors (3) and terminal #7 of the hi/lo limit board (5). Terminal #7 is an output. It remains powĆ ered after the oven is shut down to keep the convection fans (6) operating until the unit reaches 135-170F (57-77C) as sensed by the thermocouples (7).

NOTE: Two thermocouples are located beĆ

2. Turn the heat switch (8) to ON. Power goes to terminal #6 of the temperature controller (2) and terminal #5 of the Hi/Lo limit board (5). A switch is made between terminals #5 and #6 of the Hi/Lo board. This switch opens if the oven cavity temperature exceeds 600F (316C). Terminal #6 of the Hi/Lo board is an output and sends power to a convection presĆ sure switch (9). The switch reacts from a vacuĆ um created by the convection fans. If the switch is closed, power runs to the combustion motor (10), the common terminal of the burner pressure switch (11), and terminal #7 of a TPDT relay (12).

NOTE: This relay acts as a latching relay and

remains powered up even after the burner pressure switch changes state.

The burner pressure switch should be made between common and N.C., sending power to terminal #4 and the coil of the latching relay.

3. When the combustion motor (10) reaches full speed, the burner pressure switch (11) toggles between common and N.C. to common and N.O. Power goes to terminal #9 of the latching relay (12). This relay is latched due to voltage passing from terminal #7 through a set of closed contacts to terminal #4 to its coil. A set of contacts are also closed between terminals #9 and #6 of the same relay, sending power to a 10 second purge timer (13). When the timĆ

3-19

Page 46

OPERATION

er times out, power goes to the coil of a SPST relay (14), allowing its contacts to close.

4. On a call for heat from the temperature controlĆ ler (2), as sensed by the thermocouples, a set of contacts closes sending power out of termiĆ nal #4 of the temperature controller to the common terminal of the SPDT thermal switch (15). The switch toggles if the temperature passing its face exceeds the rating on the back of the switch.

NOTE: The switch is located in the front conĆ

trol compartment. It protects the other components from hi ambient heat.

If this switch is cold, it should be made beĆ tween common and N.C. terminals sending power to one side of the SPST relay (14). This relay was closed shortly after the 10 second purge timer (13) timed out. Power is sent to terĆ minal #1 of the Landis and Gyr ignition control system (16). Terminal #8 of the ignition control module is an output. It sends power to a 2 secĆ ond purge timer (17) and the pilot valve (18). The main valve (19) opens when the 2 second purge timer times out. If the ignition control senses a flame the system remains energized. If not, the control locks out within 1 to 3 secĆ onds. The ignition alarm light (20) illuminates.

NOTE: This system is polarity specific. If the

unit locks out repeatedly and the D.C. microamps are within the acceptable range, check for proper polarity.

5. When power is applied to the coils of both moĆ tor contactors (3) the contacts close sending power to the four convection fans (6) located in the back of the oven. Power is also applied to the coil of the SPST relay (4).

NOTE: The SPST relay acts as a hood interĆ

lock and is sometimes used as a means of starting the hood.

6. The oven has six cooling fans (21). Two on the front control panel keep the panel below 140F (60C). The fan's airflow is from left to right for flow through ventilation. The other four, in the rear of the oven, keep the convection fans from

overheating. The cooling fans start when the motor contactor powers up and closes beĆ tween terminals #3 and #4. Power goes to the N.C. terminal of a SPDT thermal switch (22). The switch toggles if the temperature passing its face exceeds the rating on the back of the switch and may start the fans even if the oven is off. If this switch is cold, it should be made between common and N.C. terminals sending power to the cooling fans.

NOTE: The switch is located on the ceiling of

the convection fan compartment.

7. The conveyor is driven by an open loop D.C. control system consisting of a conveyor switch (23), time display (24), 10kW potentiometer (25), D.C. speed control board (26), 180 VDC motor (27) and #10 Hall effect pickup (28). ReĆ fer to page 5-1 for pickup troubleshooting. AfĆ ter the conveyor switch is turned on, the time display illuminates. The D.C. control board powers up. The output voltage measured on terminals A1 and A2 of the board to the motor varies from 20 to180 VDC based on the posiĆ tion of the potentiometer. The speed of the moĆ tor should also vary. The time display varies deĆ pending on the speed of the Hall effect pickup. The pickup sends an R.P.M value to the disĆ play. The display converts this value to minĆ utes:seconds.

NOTE: This type of system does not sense the

weight of the product and will slow down slightly if the belt is fully loaded.

8. If the thermal switch (15) in the control panel toggles due to high heat power is interrupted to the ignition control system. Power runs through a momentary switch (29) to the coil of a 220 or 240 volt relay (32). When this relay closes, a buzzer (30) sounds and an indicator lamp (31) lights, indicating a control compartĆ ment high temperature. Pressing the momenĆ tary switch disengages the relay, silencing the buzzer. The indicator lamp remains lit until the temperature drops 20F (11C) across the face of the thermal switch, allowing the burner to refire.

3-20

Page 47

MT3255 and MT3270

5 5 5

2020

FIGURE 6

3-21

Page 48

OPERATION

5 5 5

4A 4B

1919

FIGURE 7

3-22

Page 49

MT3255 and MT3270

18 18

FIGURE 8

3-23

Page 50

OPERATION

17 17 17

FIGURE 9

3-24

Page 51

MT3255 and MT3270

5 5 5

17 17

FIGURE 10

3-25

Page 52

OPERATION

5 5 5

FIGURE 11

3-26

Page 53

MT3255 and MT3270

21 21

FIGURE 12

3-27

Page 54

OVEN ADJUSTMENTS FOR COOKING

OPERATION

TEMPERATURE

The internal temperature of your product is very imĆ portant; and should be taken as soon as the prodĆ uct completely exits the cooking chamber. This reading will give a general indication of whether or not the product is fully cooked. A multiple topping pizza, for example, will be cooked if the internal temperature is over 160Ć165F (64Ć67C). For a single topping, such as cheese, the temperature should be greater than 170Ć180F (69Ć74C).

CONVEYOR SPEED TIME VS. TEMPERATURE

Typically, as the temperature increases, the time decreases. Conversely, as the temperature deĆ creases, the time increases. To find a good bake time and temperature, one or the other should reĆ main constant. For example, if the temperature is set at 480F (224C) and the belt speed is set at 7 minutes 30 seconds, but the pizza is not as brown as desired, keep the time setting the same and inĆ crease the temperature to 500F (234C).

ing the screws and wing nuts provided, (one strip covers one group of holes). Locate the Air Flow Plate into the track, sliding it back into the oven. Replace the End Plug.

Here are some suggestions for setting up the air flow. Keep in mind that the first half of the oven is used for the initial baking of the product and the last half is used for browning. We will use pizza as an example.

EXAMPLE:

A good bake time and temperature have been esĆ tablished, but more browning on top of the pie is desired. Relocate one of the blockĆoff plates" above the belt to open a few rows of holes toward the exit end of the oven. This will allow more of the superheated air to brown the top just prior to exitĆ ing the oven.

EXAMPLE:

The bottom of the pie is golden brown, but the top is a little too dark. Closing off some of the air flow from the top at the exit end of the oven will cure this problem. Leave the time and temperature at the same settings.

AIR FLOW ADJUSTMENTS

Since a variety of products can be cooked in this oven, special settings for air flow must be made for your product. Unless otherwise specified, Blodgett Mastertherm conveyor ovens are shipped from the factory with only partial air flow above the conĆ veyor. This means that most of the air flow holes are blockedĆoff" via steel strips which stop the heated air from reaching the item being cooked. These strips or blockĆoff plates" can be easily relocated to regulate the amount of air for your particular needs. The area below the belt has all air flow holes open.

1. Remove the End Plug from the side of the oven that needs adjusting.

2. Using the handle supplied with the oven, pull out the Air Flow Plate. On occasion, it may be necessary to bang" the air plate from underĆ neath to pop" it from it's air seals.

3. Notice the Air Flow BlockĆoff" Plates. After the amount of air flow required has been deterĆ mined, either remove or relocate the plate usĆ

EXAMPLE:

The top of the pie is too dark, but either the bottom is not done enough, the center of the pie is doughy, or the ingredients are not fully cooked. Open some of the rows of holes above the conveyor at the entry half of the oven and close off the holes at the exit. This will allow the superheated air to penetrate the pie from the top and bottom (at the beginning of the cooking cycle) quicker. As a result the center of the crust and/or ingredients will be cooked before the pie starts the browning stage. Leave the time and temperature at the same settings.

WARNING!!

In the event of a power failure, all switches should be turned off, and no atĆ tempt should be made to operate the appliance until power is restored.

In the event of a shut-down of any kind, allow a five (5) minute shut off period beĆ fore attempting to restart the oven.

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MT3255 and MT3270

This page intentionally left blank.

3-29

Page 56

CHAPTER 4

CALIBRATION AND

ADJUSTMENT

Page 57

MT3255 and MT3270

CONVECTION BLOWER MOTORS

TO CHECK MOTOR ROTATION

1. Remove the back of the oven body and verify proper motor rotation. (See FIGURE 1)

For motor placement, the direction of rotation is viewed left to right from the oven's rear. Typically the motor direction is referenced to the end of the shaft (EOS). However due to the vertical positionĆ ing of the motors in Mastertherm ovens, it is more instructive to reference the end of the motor (EOM) as looking from the rear of the oven. In FIGURE 1 all directions are taken from EOM. The correct rotaĆ tion amperage draw is approximately 1 amp. If the measured amperage is less than .5, check for proper motor rotation direction.

Blower

Motor

TO CHECK LOWĆLIMIT

1. Turn the oven on and let it heat up to approxiĆ

mately 200F (93C).

2. Shut the oven off. The blowers should come back on in several seconds.

3. When the blowers shut off, turn the oven on.

If computer controlled press the ACT TEMP" key to verify that the blowers shut off between 135F (57C) and 170F (77C). If the blowers do not shut off refer to the Troubleshooting section page 5-3.

For standard controls, turn the blower switch to on to record the temperature. Adjust the hi/ lo board if necessary. See page 4-6 for temĆ perature calibration procedure.

Slinger

Cooling Blade

MT3270 BLOWER WHEEL ROTATION

Motor

(Side view)

Motor #1

(CW)

Motor #2

(CCW)

Motor #3

(CW)

(Top view)

Motor

Motor #4

(CCW)

Control

Box

Control

Box

FIGURE 1

MT3255 BLOWER WHEEL ROTATION

Motor

(Side view)

Motor #1

(CW)

Motor #2

(CCW)

Motor #3

(CCW)

(Top view)

Control

Box

Control

Box

4-1

Page 58

REGULATED GAS PRESSURE

CALIBRATION AND ADJUSTMENT

1. Let the oven run up to 510F (266C). You may

now verify the operational and regulated gas pressures.

Incoming static gas pressure to the unit, with all the gas appliances drawing from the supply, should be a minimum of 5.5" W.C. (13.7 mbar) for natural gas and 11" W.C. (28 mbar) for propane gas. The manĆ ifold pressure, if measured after the regulator loĆ cated inside the control box, must be 3.5" W.C. (9 mbar) for natural gas and 10" W.C. (25 mbar) for propane gas. For CE pressures reference TABLE 2 on page 1-3 of the Introduction.

The pressure can be checked at the tap on the dual regulated gas valve or at the tap on the tee valve.

Pressure

Ta p

Regulator Cap

Regulator

Adjustment

If pressure adjustments are needed, turn the adĆ justing screw located under a screw cap of the dual regulated valve. Adjust the gas pressure by turning the screw clockwise to raise the gas pressure and counterĆclockwise to lower the gas pressure. Be sure to reinstall the screw cap; should the diaĆ phragm rupture this cap acts as a flow limiter

The air shutter disc on the burner blower motor, loĆ cated inside the control box at the top of the asĆ sembly, is factory adjusted to provide the most effiĆ cient blue flame possible at sea level. Visually examine the flame to verify it's quality. Should it need adjustment, increase or decrease the air mixĆ ture to attain the best flame quality.

Pressure Tap

Inlet

Regulator

Cap

Regulator

Adjustment

Outlet Pressure Ta p

Pressure Regulator (U.S. models)

FIGURE 2

Setting Equipment for Other Types of Gas - CE Models

1. Shut off the gas valve and turn off the operating switch.

2. Dismantle the gas block by means of couĆ plings.

3. Dismantle the main burner and replace the inĆ jector.

4. Replace pilot injector.

5. Install the burner and gas block.

6. Check for leakage and possible loose electriĆ cal connections.

7. Adjust gas pressure if necessary, See FIGURE 3.

Pressure Regulator (Some export models)

Gas Pressure Adjustment

Pressure Ta p

Pressure Regulator (CE models)

FIGURE 3

4-2

Page 59

MT3255 and MT3270

STANDARD CONTROLLER CONFIGURATION

BELT SPEED CALIBRATION - CLOSED LOOP

DART MICRODRIVE MDP

1. Remove the top cover from the unit. The interĆ nal dip switch is located next to the transformĆ er. See FIGURE 4.

Cover Slides

Out

Dip Switch Detail

12345678

O N

Display

Increase Time

(Slow Down Belt)

Decrease Time (Speed Up Belt)

FIGURE 4

DIP SWITCH FUNCTION TABLE

Switch 1 Program Constant

Switch 2 Program Minimum Setting

Switch 3 Program Maximum Setting

Switch 4 Rate/Time Mode and Decimal Decimal Point

Select

0 thru 4 = Rate/Follower Decimal 5 = Time Mode/Colon

Switch 5 Master/Follower Select OFF=MasterąON=Follower

Switch 6 DO NOT USE - SET TO OFF

Switch 7 Program/Run Select OFF=RunąON=Program

Switch 8 DO NOT USE - SET TO OFF

TABLE 1

4-3

Page 60

CALIBRATION AND ADJUSTMENT

FIELD PROGRAMMING MDP CONTROLS

While in Programming Modes, set decimal place/ mode variable to the proper position (0 thru 4 = Rate 5 = Time). This allows settings to be made in the proper units. Only set the variables that you wish to change. You can change any variable WITHOUT having to reset the others.

SETTING UP CUSTOM VALUES

To Enter Programming Mode (Motor Will Stop)

1. Make sure DIP switches 1, 2, 3, 4, 5, 6 and 8 are OFF. Flip DIP switch 7 ON.

2. Display reads PROG (in rate mode the current decimal point is also displayed.

3. Use the following instructions to view and/or edit any variable.

Displayed Decimal Place, Rate or Time Mode Select

1. Flip DIP switch 4 (Rate-Time Mode/Program Decimal Place) to ON.

2. Present decimal point (if any) will be lit, as well as the current value of the decimal place variĆ able.

3. Use Up and Down buttons to change. Use a value of 5 for Time Mode.

4. When finished, flip DIP switch 4 to OFF.

5. The display reads PROG.

The Constant

1. Calculate the constant for your application. For ovens with a 70 inch tunnel, 130 Volt DC or 90 VDC motor and #2 pickĆup, the constant is 5:20. For ovens with a 55 inch tunnel, 130 Volt DC or 90 VDC motor and #2 pickĆup, the conĆ stant is 4:08.

2. Flip DIP switch 1 (Program Constant) ON.

3. Present value for constant will appear in the display.

4. Use Up and Down buttons to change.

5. When finished, flip DIP switch 1 OFF.

6. The display reads PROG.

NOTE: If you change the constant, the display setĆ

ting will be set to the slowest speed when you exit the Programming Mode.

Program Minimum Setting

1. Flip DIP switch 2 (Program Minimum Setting) ON.

2. Present value for Lower Limit will appear in the display.

3. Use Up and Down buttons to change.

4. When finished flip DIP switch 2 OFF.

5. The display reads PROG.

Program Maximum Setting

1. Flip DIP switch 3 (Program Maximum Setting) ON.

2. Present value for Upper Limit will appear in the display.

3. Use Up and Down buttons to change.

4. When finished flip DIP switch 3 OFF.

5. The display reads PROG.

To Exit Programming Mode

1. Make sure DIP switch 5 (Master/Follower Mode select) is in the desired position (ON = Follower; OFF= Master).

NOTE: In most cases DIP switch 5 should be

set to the master position (OFF).

2. Make sure DIP switches 1, 2, 3, 4, 6 and 8 are OFF.

3. If satisfied with programming values, set DIP switch 7 to OFF.

4. The control begins to operate, using the values and modes you have programmed.

Check the Belt Speed Calibration

To check the belt speed calibration place a pan on the belt and start the conveyor.

1. Begin timing the belt's speed when the trailing edge of the pan enters the oven.

2. End the timing cycle when the trailing edge of the pan exits the oven.

3. If the displayed time differs from the actual more than 5 seconds, reprogram the K" constant. If the measured time is lower than 5 seconds, raise the K" constant in increments of 05. If the measured time is higher than 5 secĆ onds, lower the K" constant in increments of

05.

4-4

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MT3255 and MT3270

BELT SPEED CALIBRATION - OPEN LOOP

NOTE: The following procedures must be perĆ

formed after dc voltage levels have been set and are known to be accurate.

The cooking time digital display should be adĆ justed when changing any of the system compoĆ nents. Prior to adjusting the display, determine the following two specifications:

1. The number of pulses per spindle revoluĆ

tion generated by the Hall effect pickup.

Move the plastic endĆcaps on the pickup loĆ cated on the DC motor. If the pickup is marked with the number 2, it is a single pulse per revoĆ lution pickup. If the pickup is marked with the number 10 (Standard After 6Ć1Ć91) it is a five pulse per revolution pickup. Replace the endĆ caps. Refer to page 5-1 for pickup troubleĆ shooting.

2. The manufacturer and the voltage rating of

the DC drive motor.

This information is embossed on the nameĆ plate located on the motor's case.

Once the above specifications have been deterĆ mined, perform the following calibration proceĆ dures.

Set The Belt Speed DIP Switches.

Set the DIP switches using the data from the table below.

Pickup DIP Switch Setting

MT3255 - 60 Hz Motors

Single 7, 6, 5, 4, 3 ,2 , 1 - set to OFF

5 Pulse 7 - set to OFF

MT3270 - 60 Hz Motors

Single 8, 6, 2 - set to OFF

5 Pulse 7, 5, 1 - set to OFF

MT3255 - 50 Hz Motors

Single 8, 5, 3, 2 - set to OFF

5 Pulse 7, 4, 2, 1 - set to OFF

MT3270 - 50 Hz Motors

Single 8, 6, 5, 4, 3, 2, 1 - set to OFF

5 Pulse 7, 5, 4, 3, 2, 1 - set to OFF

TABLE 2

1. Remove the screws securing the cooking time display lens cover. Remove the lens cover. If a 5 pulse pickup is used, verify that the multiplier potentiometer is set to the x10 position (refer to FIGURE 5 for the potentiometer location).

Belt speed DIP switch located

behind cooking time digital display

Cooking Time

INCREASE DECREASE

X10

Multiplier potentiometer located behind cooking time digital display

For 5 pulse pickups set to x10

FIGURE 5

Rear Of

Control

OFF

Switch Number

87654321

128 64 32 16 8 4 2 1

Switch Value

FIGURE 6

4-5

Page 62

CALIBRATION AND ADJUSTMENT

TEMPERATURE CALIBRATION - UNITED ELECTRIC CONTROLLER

NOTE: Th U.E. and Zytron boards get input from eiĆ

ther single or dual lead thermocouples.

LOW LIMIT ADJUSTMENT

1. Bring the oven to 200F (93C).

2. Turn both the blower and the heat switches to OFF. The blower should continue to run.

3. Monitor the digital temperature control display. The blower motors should shut off within the range of 170Ć135Fāāā(77Ć57C).

4. To adjust the temperature, turn the lowĆlimit potentiometer. A clockwise rotation increases the setting, counterĆclockwise decreases it. See FIGURE 7.

TEMPERATURE CALIBRATION

1. With the conveyor turned off, place a pyromeĆ ter in the center of the oven cavity.

2. Adjust the set point for 500F (260C). Monitor the Indicator Lamp. See FIGURE 7. When the lamp goes out, compare the pyrometer with the temperature of the display. If the display difĆ fers by +/Ć5F (3C), open the access panel on the temperature controller and continue with STEPS 3 and 4.

lowers the display reading and raises the temĆ perature. A counterĆclockwise rotation raises the reading and decreases the temperature. Check the oven set point. Adjustment of the potentiometer may affect this reading. Bring the oven up to 525F (274C). Verify the caliĆ bration.

4. Set Point Adjustment Ć Adjust the Coarse ManĆ

ual so the controller calls for heat at 522F (272C) and shutĆoffs at 525F (274C). A clockwise rotation raises the temperature, counterĆclockwise lowers it.

HIGH LIMIT ADJUSTMENT

1. Turn both the blower and the heat switches to ON.

2. Set the temperature to 620F (327C). When the display reads 600F (316C), the burner blower motor should shut off. If the temperaĆ ture rises above 600F (316C), adjust the hiĆ limit pot (See FIGURE 7) so the burner shuts off at 600F (316C). A clockwise rotation of the highĆlimit pot increases the temperature, counterĆclockwise decreases it.

NOTE: Repeat Low Limit Adjustment STEPS 1Ć3 to

verify new settings.

3. Adjust the Meter High Set so the display matches the pyrometer. A clockwise rotation

INCREASE

DECREASE

ZYTRON

SERIES 300

13 265

230

115

NO C NC

OUTPUT 1

Zytron Board

INCREASEDECREASE

INCREASE

HI LIMIT

1 2 3 4 5 6 7 8

230 115 NC C NO NO C

DECREASE

LOW LIMIT

United Electric Board

INCREASE

DECREASE LOW LIMITP2HI LIMIT

FIGURE 7

910

T/C

RED

478

NO C

OUTPUT 2

Lamp

Set Point

Coarse Manual

Meter

High Set

Panel

Flips Down

Band

Width

Set Fully

CCW

Cycle Time

Set Fully

Temperature Control Board

4-6

Page 63

MT3255 and MT3270

TEMPERATURE CALIBRATION - ATHENA CONTROLLER

THE CONFIGURATION MENUS

1. Press and hold the actual temperature key for approximately 10 seconds. When the menu system has been accessed, the display toggles between and either or .

Setting the Default Display

The default display determines whether the conĆ troller displays the actual or the setpoint temperaĆ ture.

1. Use the arrow keys to select the desired disĆ play default.

NOTE: We recommend using the setpoint disĆ

play default.

2. Press the actual temperature key to enter the selected display default. The display will toggle between and a numerical value.

Setting the Control Hysteresis

The control hysteresis, or the burner cycle is used to prevent rapid cycling around the setpoint. The hysteresis is adjustable from 2F to 252 F (0C to 140C).

1. Use the arrow keys to select the desired conĆ trol hysteresis.

NOTE: We recommend using the 5 F initially.

2. Press the actual temperature key to enter the selected hysteresis value. The display will toggle between and a numerical value.

Setting the Display Offset

The display offset is used to provide a limited adĆ justment of the displayed temperature as a comĆ pensation for offsets between the actual temperaĆ ture and the temperature seen by the thermocouple. The display offset is adjustable from Ć126F to +126F (Ć70C to 70C).

1. Use the arrow keys to select the desired disĆ play offset.

2. Press the actual temperature key to enter the selected offset value. The display will toggle between and a numerical value.

Setting the Deviation Band Alarm

The deviation band alarm causes the display to flash when the actual temperature varies (in either direction) from the setpoint. The deviation band alarm is adjustable to off or values from 1F to 252F (1C to 740C).

1. Use the arrow keys to select the desired deviĆ ation band alarm.

2. Press the actual temperature key to enter the selected alarm value.

To exit the Configuration Menus

1. Push and hold the actual temperature key for approximately 3 seconds.

NOTE: The unit exits the configuration menus if the

controller is not touched for 1 minute at any time during the programming process.

SETTING THE DISPLAY UNITS

1. Disconnect the power from the control. ReĆ move all wires and the back of the control.

2. Locate the black jumper on the microcontroller board next to the thermocouple connection. Install the jumper on both pins.

3. Reconnect the power to the control.

4. Press and hold the actual temperature key for approximately 10 seconds until the display reads and flashes or . Press the up or down arrow key to toggle between F and C.

5. Press and hold the actual temperature key unĆ til the control exits the programming mode.

NOTE: DO NOT disconnect power and move the

jumper back to single pin until the control has returned to normal operation.

LOW LIMIT ADJUSTMENT

1. Bring the oven to 200F (93C).

2. Turn both the blower and the heat switches to OFF. The blower should continue to run.

3. Monitor the digital temperature control display. The blower motors should shut off within the range of 170Ć135Fāāā(77Ć57C).

4. To adjust the temperature, turn the lowĆlimit potentiometer. A clockwise rotation increases

4-7

Page 64

CALIBRATION AND ADJUSTMENT

the setting, counterĆclockwise decreases it. See FIGURE 8.

HIGH LIMIT ADJUSTMENT

NOTE: Refer to the wiring diagram located on the

oven or on page 3-21 of the Operation section. For additional assistance call the Blodgett Service department.

1. Remove the wires from the common and N.O. terminals. Touch the wires together to energize

INCREASE

DECREASE

ZYTRON

SERIES 300

13 265

230

115

NO C NC

OUTPUT 1

Zytron Board

INCREASEDECREASE

INCREASE

HI LIMIT

1 2 3 4 5 6 7 8

230 115 NC C NO NO C

DECREASE

LOW LIMIT

United Electric Board

INCREASE

DECREASE LOW LIMITP2HI LIMIT

the heat circuit. This enables the oven to heat above the highest temperature allowed by the controller.

2. When the display reads 600F (316C), the

burner blower motor should shut off. If the temĆ perature rises above 600F (316C), adjust the hiĆlimit pot (FIGURE 8) so the burner shuts off at 600F (316C). A clockwise rotation of the highĆlimit pot increases the temperature, counterĆclockwise decreases it.

910

T/C

RED

ACTUAL SETPOINT HEAT

Athena Temperature Controller

478

NO C

OUTPUT 2

FIGURE 8

4-8

Page 65

MT3255 and MT3270

COMPUTER CONTROLLER CONFIGURATION

COMPUTER CONTROLS

INITIATING ACCESS MODE

The Cooking Computer provides a special Access Mode for setting and displaying certain computer special functions. To initiate the Access Mode place the control in the OFF state, (OFF is shown in the display when power is first applied to the control). Press the following sequence of keys to set the control to Access Mode: CLEAR 1 2 3 4 5 6 ENTER. The display reads ACCESS.

DISPLAY ACTION

DISPLAY ACTION TAKEN

TAKEN

F/CMODE? Press

POS OFFSET? Press

NEG OFFSET? Press

MAXĆT ENTRY? Press

PROG

T  F(C)

ENTER

PROG

0(0) Press

ENTER

PROG

0(0) Press

ENTER

PROG

600(315) Press or change then

ENTER

CONFIGURATION

When the controller is in the ACCESS" mode, press the following buttons: CLEAR 1 1 1 ENTER. With the exception of the positive and negative offĆ sets, to be addressed later, all display data should correspond to the entries in the chart below. If the data does not match the chart, it should be changed accordingly. When the correct data is disĆ played press the PROG/ENTER key, the display will cycle on to the next screen. If a step is missed, press the CLEAR button to backup.

Press again or hit any number and

press again.

PROG

ENTER

PROG

ENTER

PROG

ENTER

PROG

ENTER

it will change.

MAXĆT LIMIT? Press

READY BAND? Press

MINĆHT ON? Press

DISPLAY INTEG? Press

TĆCTRL INTEG? Press

PROG

625(330) Press

ENTER

PROG

10 Press

ENTER

PROG

60 Press

ENTER

PROG

30 Press

ENTER

PROG

10 Press

ENTER

NOTE: Press the CLEAR key to back up one paĆ

rameter.

TABLE 3

PROG

ENTER

PROG

ENTER

PROG

ENTER

PROG

ENTER

PROG

ENTER

4-9

Page 66

Boost Option - (versions 2.00 or 3.00)

When the controller is in the ACCESS" mode, press the following buttons: CLEAR 2 1 2 ENTER to enter the boost option.

CALIBRATION AND ADJUSTMENT

DISPLAY

ACTION

DISPLAY ACTION TAKEN

TAKEN

BOOST / MODEĆ? (Flash alternately)

Press

PROG

ENTER

OPTĆ1 or OPTĆ2

Select OPTĆ1 to turn off boost mode.

OPTĆ1 Press

PROG

ENTER

DONE SAVE EXIT

EXITING THE ACCESS MODE

After pressing PROG/ENTER the last time, the disĆ play will show EXIT" then beep and return to the ACCESS" mode. Pressing and holding the ON/ OFF key will turn the oven on. A new time and temĆ perature must be entered upon exiting the ACĆ CESS" mode since the oven will automatically default to 0. The oven will not fire until both time and temperature are entered.

TABLE 4

Press any numeric key to toggle between OPTĆ1 and OPTĆ2

Press

PROG

ENTER

Firmware Model Version Display

Password: CLEAR 1 2 3 ENTER

MODEL Ć Computer Model Number - 6028 (Blodgett Conveyor Oven With Speed Control)

SWĆVER Ć Firmware version number. VĆxxyy xx = major version, yy = minor version

DATEĆ? ĆFirmware release date

CHKSUM Ć ROM checksum stored in PROM. xxxx Ć Value is display in hexadecimal format.

4-10

Page 67

MT3255 and MT3270

TEMPERATURE CALIBRATION

TO ENTER THE CALIBRATION MODE

1. Press the ON/OFF key until OFF is displayed.

2. Press CLEAR 1 2 3 4 5 6 ENTER to enter the access mode. The display reads ACCESS.

3. Press CLEAR ACT_TEMP ACT_TEMP ACT_TEMP ENTER to access the Temperature Calibration mode.

4. Disconnect the white wire from the D.C. motor. Secure so the wire will not ground against any part of the oven. This will disable the conveyor.

NOTE: Disregard the controller display. The only

numbers of concern are the pyrometer reading and the temperature set point.

TO CALIBRATE THE OVEN TEMPERATURE

During operation, the temperature control is based on the measured temperature and the temperaĆ ture offset which is programmed into the control. If the temperature measured in the center of the oven is below the oven setpoint a positive offset is needed. If the temperature measured in the center of the oven is above the oven setpoint a negative offset is needed.

NOTE: In the calibration mode the display gives

the current measured temperature only.

To view the current temperature setpoint:

1. Press the SET_TEMP, key.

To change the temperature setpoint :

1. Press PROG/ENTER SET_TEMP.

2. Enter the desired setpoint.

3. Press the PROG/ENTER key.

To program the temperature offset:

To change the temperature calibration an offset, positive or negative, must be programmed.

1. Press PROG/ENTER followed by ACT_TEMP. The display flashes either POS * OFFSET or

NEG * OFFSET

NOTE: POS OFFSET is displayed if a value has

been programmed in for a positive offĆ set. NEG OFFSET is displayed if a valĆ ue has been programmed for a negaĆ tive offset. The only time both will be displayed is if a value of 0 has been enĆ tered for both.

2. Enter a value for the desired offset. The display flashes DISPLAY * INTEG?.

3. Press the PROG/ENTER key. The default value of 30 will be displayed.

4. Press the PROG/ENTER key. The display will flash TĆCTRL * INTEG?.

5. Press the PROG/ENTER key. The default value of 10 will be displayed.

6. Press the PROG/ENTER key.

The control will now resume using the new paramĆ eters.

Verify the temperature calibration once the unit has cycled for 5 minutes with the new settings. Repeat calibration using a new offset value if necessary.

TO EXIT THE CALIBRATION MODE

1. Press the CLEAR key twice.

2. The display flashes REBOOT then displays the set time and temperature. You must reĆenter a temperature for the oven to start heating again.

A.) Press PROG/ENTER SET_TEMP

B.) Enter the desired temperature.

C.) Press the PROG/ENTER key. The heat

light turns on and the burner begins to cycle at set point.

4-11

Page 68

BELT SPEED CALIBRATION

CALIBRATION AND ADJUSTMENT

To enter the calibration mode:

1. Press the ON/OFF key until OFF is displayed.

2. Press CLEAR FRONT BELT, FRONT BELT, FRONT BELT, PROG/ENTER to enter the AcĆ cess mode. The display flashes ACCESS.

3. The display reads ACTIVE BELT-?. Press front belt for Front Belt Calibration

4. The display reads FRONT-INIT-F.

Belt speed calibration:

1. The display reads BELT SIZE-?. Enter the length of the conveyor belt for your model. See TABLE 5. Press the PROG/ENTER key.

2. The display reads STEP-1. The controller is in Step 1 of the calibration procedure: maximum belt speed. The motor control is automatically set to its maximum output. Place an object on the belt and note the time from entrance to exit.

NOTE: Be certain to measure either the leadĆ

ing edge in and out or the trailing edge in and out. Do not use the leading edge in and the trailing edge out.

A.) The display reads STEP-1TIME-?. Enter

the time measured in STEP-1. Min: 0 Max: 59:59 (min:sec). Press the PROG/ ENTER key.

B.) The display reads STEP-1DIST-?. Enter

the belt length for your model. See NO TAG. Press the PROG/ENTER key.

3. The display reads STEP-2. The controller is in Step 2 of the calibration procedure: minimum belt speed. The motor control is automatically set to its minimum output.

The belt will travel very slowly during this part of the calibration procedure. To minimize the time spent on STEP-2, measure off 10" on the conveyor support. Place an object on the belt and note the travel time for the 10" measured distance.

A.) The display reads STEP-2 TIME-?. Enter

the measured travel time for STEP-2. Min: 0 Max: 59:59 (min:sec). Press the PROG/ ENTER key.

B.) The display reads STEP-2 DIST-?. Enter

10". Press the PROG/ENTER key.

4. The display reads MIN-TM ENTRY? (the fastĆ est belt speed). Limits of this value are deterĆ mined by the Step-1 and Step-2 calibration values. See TABLE 5 for correct entry for this model. Press the PROG/ENTER key.

5. The display reads MAX-TM ENTRY? (slowest belt speed). Limits of this value are determined by the Step 1 and Step 2 calibration values. Use 1600 (16 min). Press the PROG/ENTER key.

6. The display flashes DONE and SAVE.

Repeat the procedure for the rear belt by pressing, CLEAR, REAR BELT, REAR BELT, REAR BELT, PROG/ENTER.

NOTE: During these adjustments, pressing the

clear button will abort all entries and reĆ quire reprogramming of belt time mode. When exiting the Belt Speed Calibration Mode, enter a time. Otherwise the time deĆ faults to zero and the oven will not heat, and the belt will not move.

Oven

Type

MT1828 28 330 (3 min, 30 sec) MT3270 70 330 (3 min, 30 sec)

MT2136 36 200 (2 min) MT3855 55 330 (3 min, 30 sec)

MT3240 40 300 (3 min, 00 sec) MT3870 70 330 (3 min, 30 sec)

MT3255 55 300 (3 min, 00 sec)

Belt Length/

Distance

Minimum

Oven Entry

TABLE 5

4-12

Oven

Type

Belt Length/

Distance

Minimum

Oven Entry

Page 69

MT3255 and MT3270

MOTOR CONTROL BOARD ADJUSTMENT

NOTE: This procedure does not apply to Dart MiĆ

crodrive systems.

High/low speed motor control board adjustĆ ment for 180 and 130 volt DC motors

NOTE: The motor control board is located on the

slide out control panel.

High Speed Motor Adjustment:

Follow Belt Speed Calibration through STEP 2 (see page 4-12).

1. With the motor connected (make no open cirĆ cuit voltage readings) measure the voltage at the motor leads (A1 & A2 in FIGURE 9) on the DC control board. If the voltage is not within 3 VDC of the specified voltage continue with step 3.

2. Turn the MAX trim pot counterĆclockwise to lower and clockwise to raise the voltage until it is within 3VDC of the specified voltage.

NOTE: For computerized closed loop sysĆ

tems this adjustment must be made quickly.

Low Speed Motor Adjustment:

Continue Belt Speed Calibration through STEP 3 (see page 4-12).

1. With the motor connected (make no open cirĆ cuit voltage readings) measure the voltage at the motor leads on the DC control board (A1 & A2 in FIGURE 9). If the voltage is not 26VDC +/Ć 1 VDC, continue with step 3.

COMPUTERIZED OVENS

130 Volt System 180 Volt System

Model Low High Low High

MT1828 20 130 26 180

MT2136 20 130 26 180

MT3240 20 130 26 180

MT3270 26 130 26 180

MT3855 26 130 26 180

MT3870 26 130 26 130

NONĆCOMPUTERIZED OVENS

MT2136 20 130 26 180

MT3255 26 130 26 180

MT3270 26 130 26 180

MG3270 26 130

24 VDC SYSTEM

MT1820 3.0 21

TABLE 6

2. Turn the MIN SPEED pot clockwise to lower the voltage and counterĆclockwise to raise the voltĆ age.

NOTE: If any voltage adjustments were made hit

the CLEAR key to abort the calibration mode. Reenter the calibration mode to verify that voltage is locked in.

4-13

Page 70

CALIBRATION AND ADJUSTMENT

Acceleration Adjustment

Yellow or Violet (pin 12)

Orange or Gray (pin 10)

Blue (pin 8)

Violet

Gray

Blue

Speed Pot

NOTE: Colors may vary

between early ovens.

Line Fuse

Minimum Speed

Maximum Speed

Socket J1

TB1

ACC MAX MIN

Test

Points

L N A1 A2

TP1

TP2

Torque (current) limiting adjustment (DO NOT ADJUST)

Switches 2,4,5,6,7

TORQ

DIP Switch on

early models only

REG

Regulation Adjustment

Armature Fuse

Line Hot (VAC)

Line Neutral (VAC)

PM Motor Armature

Barrier Terminal Block TB1

Power Line and Motor Ground

REMOVE RED PLUG FROM TOP OF DC MOTOR PRIOR TO OPERATING!

Warning: Circuit components are not at ground potential! Use only a nonĆmetallic or

insulated adjustment tool. Shock hazards may occur with conducting tools!

FIGURE 9

4-14

Page 71

MT3255 and MT3270

RERATING THE APPLIANCE

Due to the lack of oxygen at higher elevations, the unit may need to be rerated. (The orifice size may need to be adjusted to accommodate different air pressures at higher elevations.) If not rerated, inĆ complete combustion may occur releasing AldeĆ hydes and CO or Carbon Monoxide. Any of these

are unacceptable and may be hazardous to the health of the operator.

To choose the correct orifice for different altitudes several factors must be known:

1. Altitude

2. BTUs per burner

3. Manifold pressure

4. Correct orifice size at sea level

5. BTU value of the gas

The following are generally accepted heating values:

A.) Natural Gas - 1000 BTU/Cu Ft

B.) Propane - 2550 BTU/Cu Ft

C.) Butane - 3000 BTU/Cu Ft

6. Specific gravity

The following are generally accepted values (Air = 1.0):

A.) Natural Gas - 0.63

B.) Propane - 1.50

C.) Butane - 2.00

NOTE: For other gases contact your local gas supĆ

plier for values.

Use the following formulas to calculate the correct orifice:

Firing rate

1. # of burners

BTU per burner

2. Heating value of Gas

CuFt/Hr

3. Specific Gravity Multiplier

4. Use TABLE FĆ1 from the National Fuel Gas

Code Handbook to determine the proper oriĆ fice size at sea level.

NOTE: The sea level orifice size is needed to

determine the proper orifice at any elevation.

5. Use TABLE FĆ4 from the National Fuel Gas

Code Handbook to determine the correct oriĆ fice for the applicable elevation.

6. Use TABLE FĆ3 from the National Fuel Gas

Code Handbook to determine the specific gravity multiplier.

EXAMPLE

Known factors:

1. Altitude = 5000 ft.

2. BTUs per appliance = 55,000

3. Number of burners = 2

4. BTU value of the gas = 900

5. Specific gravity = .50

Calculations:

=ąBTU per burner

=ąCuFt/hr

=ąEquiv. CuFt/h

55,000

1. 2

27,500

2. 900

30.55

1.10

Using the tables in the National Fuel Gas Code Handbook we can determine that:

1. Correct orifice size at sea level = #40

2. Correct orifice size at 5000 ft = #42

4-15

=ą27,500 BTU per burner

=ą30.55 CuFt/hr

=ą27.77 Equiv. CuFt/hr

Page 72

CHECKING THE FIRING RATE

CALIBRATION AND ADJUSTMENT

Method #1

1. Turn off all other appliances on the line. Turn on the appliance to be measured.

2. Using either the 1/2 cu. ft. or the 2 cu. ft. dials located on the gas meter, note the time it takes the indicator to complete one revolution. See FIGURE 10.

3. Use the following formula to determine the firĆ ing rate of the meter.

3600 x size of test dial x 1000

=ĂBTU/burner

# of seconds per revolution

Example:

A.) 3600 x 2 = 7200

7200

B.)

=Ă120 Cu. Ft./Hr

C.) To convert to BTU/Hr, multiply by one of the

following generally accepted heating valĆ ues:

Natural Gas - 1000 x 120 = 120,000 BTU Propane - 2550 x 120 = 306,000 BTU Butane - 3000 x 120 = 360,000 BTU

NOTE: You may also use TABLE XII from the

National Fuel Gas Code Handbook to aid in determining the firing rate of the appliance. This table eliminates the use of the formulas above.

Locate the time observed in STEP 2. Move across the table to either the 1/2 cu. ft. or the 2 cu. ft. column to find the gas input to the burner.

FOOT

HALF

100 THOUSAND 10 THOUSAND 1 THOUSAND1 MILLION

TWO

FEET

CUBIC FEET

TYPICAL DOMESTIC GAS METER INDEX

FIGURE 10

Method #2

You may also determine the firing rate by sizing the main burner orifice and measuring manifold gas pressure. Either way is accurate, however method #1 is faster.

4-16

Page 73

MT3255 and MT3270

This page intentionally left blank.

4-17

Page 74

CHAPTER 5

TROUBLESHOOTING

Page 75

MT3255 and MT3270

DC DRIVE SYSTEM

POSSIBLE CAUSE(S) SUGGESTED REMEDY

Symptom #1 - Belt does not move (standard controls)

 Conveyor switch is turned off.

 Armature fuse on Bodine board is blown.

 Turn switch to on.

 Ohm this fuse out to determine if blown. If necesĆ

sary, replace with 250 milliamp fuse. Determine the amp draw of the motor.

 Line fuse on Bodine board is blown.

 DC motor is leaking oil.

 Motor ohms out higher then 162W.

 Motor ohms out lower then 100W.

 Brushes worn.

 Control fuses blown.

 Replace with 5 amp fuse.

 Replace motor.

 Replace brushes.

 Check wiring going from the front control panel

to the burner compartment for damage.

 Potentiometer does not ohm out correctly, 10kW.

 Replace potentiometer.

Symptom #2- Belt does not move (closed loop systems)

 Conveyor switch is turned off.

 DC motor is leaking oil.

 Motor ohms out higher than 162W.

 Motor ohms out lower than 100W.

 Brushes worn.

 Turn switch to on.

 Replace motor.

 Replace brushes.

 Control fuses blown.

 Dart microdrive not programmed.

 Hall effect pickup defective.

 Check wiring going from the front control panel

to the burner compartment for damage.

 See page 4-4 for programming.

 To check the pickup, run the belt as slow as posĆ

sible. Connect the leads of the meter to the termiĆ nals with the black and red wires. The meter should read 5VDC. (The meter should have an anolog bar in it for the remainder of the test.) ConĆ nect the leads of the meter to the terminals with the white and red wires. The bar should pulse. Connect the leads to the white and black wires. The bar should pulse, if not replace pickup.

5-1

Page 76

POSSIBLE CAUSE(S) SUGGESTED REMEDY

Symptom #3 - Belt does not move (computer controls)

TROUBLESHOOTING

 Oven in OFF mode.

 Loose computer controller cord connection.

 Time not programmed into computer.

 Emergency stop switch on OFF.

 Control circuit breaker tripped.

 Belt hooked on something in oven.

 5 amp line fuse blown.

 200 milliamp armature fuse blown.

 Hall Effect Pickup not connected. (Closed loop

systems only)

 Motor brushes worn out.

 Defective conveyor drive motor.

 Defective conveyor drive motor controller.

 Wire from pickup open or misplaced.

 DAC defective.

 9 or 25 pin cable defective.

 Turn to ON position.

 Adjust and retighten cables and set screws.

 Program in a cook time. See Operation Section

(page 3-6).

 Pull switch out to ON.

 Reset breaker.

 Turn oven OFF, unhook and repair problem.

 Replace fuse. Determine amp draw.

 Verify the unit is set for a single pulse pickup. If

not, reset for a single pulse pickup. If yes reattach the pickup.

 Replace brushes.

 Replace conveyor drive motor.

 Replace conveyor drive motor controller.

 Repair or replace wire.

 Replace computer.

 Replace cables.

 Belt speed relay defective.

 Replace relay.

Symptom #4 - Computer error code MOTOR Ć SPEED Ć ERROR

 Belt speed needs calibration.

 Voltage from Bodine controller to DAC not presĆ

 See Calibration and Adjustments (page 4-12).

 Replace the drive motor controller.

ent. The DAC (Digital Analog Control) is a nonĆreĆ pairable component of the computer. There should be approximately 20 VDC between the red and green wires on the 3 pin connection of the DC drive board.

 DAC voltage is present but not regulated beĆ

 Replace the computer.

tween 4.7 and .47 VDC when different times are programmed into the cooking computer. MeaĆ sure the voltage between the green and blue wires of the 3 pin connection.

5-2

Page 77

MT3255 and MT3270

CONVECTION SYSTEM

POSSIBLE CAUSE(S) SUGGESTED REMEDY

Symptom #1 - Blower motor(s) not running

 Blower switch off.

 No power to the oven.

 Motor fuse blown.

 Faulty start capacitor.

 Motor burned out.

 Thermal overload tripped.

 No voltage at the motor contactor coil.

 Faulty motor contactor.

Symptom #2 - Blower motor(s) do not shut off

 Faulty motor contactor.

 Faulty thermocouple on Hi/Lo board.

 Turn switch to on position.

 Verify power to the oven. If there is no power deĆ

termine cause.

 Replace fuse. Determine the amp draw.

 Replace capacitor.

 Check draw (3 amps or greater).

 Determine if the cooling blower (or fans) are operĆ

ating. If not, verify voltage to the cooling blower. If voltage is present, replace the cooling blower motor. If voltage is not present, verify voltage through the thermal switch. If no voltage is presĆ ent, replace the thermal switch.

 Check for blown fuse or bad blower switch.

 Replace motor contactor.

 Replace contactor.

 Refer to the chart on page 6-5 of the Technical

Appendix. If the readings do not match replace the thermocouple.

 Faulty Hi/Lo board.

 Hi/Lo board is not adjusted properly.

Symptom #3 - Blower motor running backward

 Motor off by thermal overload (other fans forcing

blower to spin).

 Faulty capacitor.

 Determine if 115 VAC is coming out of #7 with the

adjustable potentiometer turned completely counterĆclockwise. If voltage is still present, reĆ place the board.

 Check and readjust Hi/Lo board. Refer to page

4-6 of Calibration and Adjustment.

 Determine if the cooling blower (or fans) are operĆ

 Replace capacitor.

5-3

Page 78

HEATING SYSTEM

POSSIBLE CAUSE(S) SUGGESTED REMEDY

Symptom #1 - Burner will not fire (standard controls)

TROUBLESHOOTING

 Oven in off mode.

 No power to the oven.

 Fuse blown on the control panel.

 Determine if the controller setpoint is above actuĆ

al.

 Intermittent Ignition Device (IID) system locked

out.

 Air pressure switch may be open.

 Blower motor(s) not running.

 High limit in front panel open.

 Hi limit on Hi/Lo limit board has been hit.

 Verify that the pilot goes out when unit is shut

down.

 Verify that combustion motor is spinning and that

the centrifugal switch is closed.

 Turn the oven on.

 Determine if the circuit breaker is tripped.

 Replace the fuse.

 If the setpoint is not above the actual, reset acĆ

cordingly.

 Reference Technical Appendix (page 6-1

through 6-3).

 Check convection blower for proper operation.

 Verify voltage to motor. If voltage is present, reĆ

place the motor or start capacitor.

 Verify that the temperature in the front panel is

lower than 140F (60C).

 Verify that the oven temperature exceeded 600F

(316C).

 If pilot does not extinguish, replace the pilot valve.

 If the motor is not spinning, check the transformĆ

er and time delay relay in the control box on the top of the combustion motor. If one or both are bad, replace. If the motor is spinning and there are not 24 volts to the ignition control box, the centrifugal switch is bad. Replace the combusĆ tion motor.

 Temperature not programmed into cooking comĆ

puter.

 Time not programmed into cooking computer.

 Heat relay defective (computer controlled

ovens).

 Gas pressure to oven too high.

 Gas pressure to oven too low.

 Program cook temperature into the computer.

 Programm cook time into the computer.

 Replace relay.

 Lower to specified gas pressure.

 Raise to specified gas pressure.

5-4

Page 79

MT3255 and MT3270

POSSIBLE CAUSE(S) SUGGESTED REMEDY

Symptom #2 - Burner will not fire (computer controls)

 Oven in OFF mode.

 Emergency stop switch on OFF.

 Control circuit breaker tripped.

 Combustion motor not running.

 Main Temperature Controller not set above ambiĆ

ent temperature.

 Manual gas valve closed.

 Intermittent Ignition Device (IID) system locked

out.

 Air pressure switch may be open.

 Blower motor(s) not running.

 High Limit control tripped.

 Turn to ON position.

 Pull switch out to ON.

 Reset breaker.

 Check transformer for primary and secondary

voltage.

 Check main control and burner valve relays to

see if closed.

 Check relay in combustion burner box. If bad reĆ

place relay.

 Set to desired temperature.

 Open valve.

 Reference Technical Appendix (page 6-1

through 6-3).

 Check convection blower for proper operation.

 Verify voltage to motor. If voltage is present, reĆ

place the motor or start capacitor.

 Verify that 625F (330C) high limit is proĆ

grammed into the controller. If so reset the high limit. Set the computer to 500F (260C). Use a pyrometer to verify the oven temperature. If the oven climbs significantly above the setpoint, use the chart in the Technical Appendix (page 6-4) to check the probe. If the probe is alright the comĆ puter may need replacement.

 Thermal switch in control compartment tripped.

 Excessive intake air temperature.

 If pilot fails to go out when the unit is shut down,

the solenoid valve is bad.

 Check hood system.

 Replace valve.

5-5

Page 80

TROUBLESHOOTING

COMPUTER CONTROL SYSTEM

POSSIBLE CAUSE(S) SUGGESTED REMEDY

Symptom #1 - Computer controller displays: PROBE Ć OPEN Ć PROBE Ć SHORT and

alarm buzzer sounds

 Internal problem with computer controller.

 Verify display integ. in the 2nd level programĆ

ming. If the controller has been programmed the computer may need to be replaced.

 Loose connections at computer controller.

 Shorted or open RTD probe.

 Tighten connections.

 Use the chart in the Technical Appendix (page

6-4) to determine if probe is bad. Replace if necĆ essary.

Symptom #2 - Computer controller displays: ERROR Ć HIGH Ć TEMP Ć LIMIT

 Actual temperature exceeds programmed limit

 Faulty burner valve relay. Replace relay.

value. Default 605F (319C).

 Internal problem with computer controller.

 Verify display integ. in the 2nd level programĆ

ming. If the controller has been programmed the computer may need to be replaced.

Symptom #3 - Oven will not reach desired temperature

 Gas pressure to oven is too low.

 Top air plates missing or not adjustable.

 Faulty RTD probe.

 Contact local gas representatives.

 Install/adjust air plates.

 Use the chart in the Technical Appendix (page

6-4) to determine if probe is bad. Replace if necĆ essary.

 Blower motor(s) running backward.

 Controller out of calibration.

 Excessive food/debris accumulation blocking

the airflow.

 Verify voltage to motor. If voltage is present, reĆ

place the motor or start capacitor.

 Recalibrate the controller. See Calibration secĆ

tion (page 4-11).

 The inside of the oven should be cleaned to reĆ

move any materials that could have dropped off the conveyor belt and possibly blocked some of the air flow holes. This would include the removal of the conveyor belt, conveyor belt supports, and the nozzles. The oven interior and all parts reĆ moved should then be cleaned with an appropriĆ ate oven cleaner safe for aluminum.

5-6

Page 81

MT3255 and MT3270

Symptom #4 - Burner operates sporadically

 Air pressure switch may be open.

 Thermal switch tripped.

 Faulty RTD probe.

 Excessive food/debris accumulation blocking

the airflow.

 Check convection blower (or 4 convection fans)

for proper operation.

 Determine the ambient temperature in the conĆ

trol compartment. If above 140F (60C) check the cooling fan operation.

 Use the chart in the Technical Appendix (page

6-4) to determine if probe is bad. Replace if necĆ essary.

 The inside of the oven should be cleaned to reĆ

5-7

Page 82

CHAPTER 6

TECHNICAL APPENDIX

Page 83

MT3255 and MT3270

INTERMITTENT IGNITION SYSTEM

PRINCIPLES OF OPERATION

Pilot flame sensing is a very important aspect of the ignition controls operation. Three zones are needĆ ed to give the proper airĆgas ratio to produce a blue pilot flame.

Zone 1 - an inner cone that will not burn because excess fuel is present.

Zone 2 - around the inner, fuel rich cone is a blue envelope. This zone contains a mixture of vapor from the fuel rich inner cone and the secondary or surrounding air. This is where combustion occurs, and is the area of highest importance for proper flame sensor location.

Zone 3 - Outside the blue envelope is third zone that contains an excessive quantity of air.

FLAME RECTIFICATION

To identify a current conducted by the flame, we use flame rectification. Place two probes in Zone 2 of the pilot flame. When the surface area of one probe is larger than the other, current tends to flow more in one direction. DC current flows in only one direction, as opposed to AC current, which alterĆ nates its direction. The current is rectified from AC to DC by increasing the surface area of one probe and decreasing the surface area of the other.

In the IID system the probes exposed to the pilot flame are the Flame Sensor and the Pilot Burner Hood. Since the surface area of the pilot hood is larger than the flame sensor, the current rectificaĆ tion process takes place. Current is conducted from terminal 4 at the control through the flame sensor cable to the flame sensor. As the current is conducted through the flame to the pilot hood, it is rectified from AC to DC because of the difference in surface area. The pilot hood is grounded back to the control, thereby completing the circuit.

Flame Sensing Circuit Current

For the ignition control to function properly, a miniĆ mum amount of current must flow through the flame sensing circuit.

As the pilot flame is established and current begins to flow in the flame sensing circuit, the current enĆ ergizes a relay. A minimum amount of current is reĆ quired to pullĆin the relay. When the relay pulls in, one set of contacts opens which shuts off the high energy spark. Another set of contacts closes, puttĆ ing 24 volts on terminal 3 which opens the main gas valve.

Current vs. Voltage

In normal operation an AC voltage will be present from terminal 4 to ground and a current will be present in the flame sensing circuit.

DC Current

AC Voltage

Positive Probe

FIGURE 1

DC Current

Current

AC Voltage

Transformer

Flame

Negative Probe

Ground

Even though an AC voltage is present, flame rectifiĆ cation occurs and a DC current flows in the sensing circuit.

For service checkout purposes, measuring these voltages and currents can provide useful informaĆ tion regarding the integrity of the ignition control.

Measuring the current flow rather than voltage is the preferred procedure. Due to the internal circuitĆ ry of the ignition control and varying input impedĆ ance of voltmeters, the measured voltage will vary depending on type and model of voltmeter being used. However, measuring the current provides a more precise evaluation of the ignition control and flame sensing circuit.

A proper reading not only indicates a functional control, but also verifies all components of the cirĆ cuit such as flame sensor, cable and ground.

6-1

Page 84

TECHNICAL APPENDIX

SERVICE PROCEDURES

Service the IID system as follows:

1. Make certain the thermostat contacts are open.

2. Check for proper supply voltage at primary and secondary of system transformer.

3. Close thermostat contacts and observe sysĆ tem.

4. Determine which system condition exists:

A.) No spark, system does not function

B.) Spark present but pilot will not light

C.) Pilot lights but main valve will not open

5. Follow the appropriate service checkout proĆ cedure to troubleshoot and repair the system.

6. Observe the system through several complete operating cycles.

VOLTAGE AND CURRENT MEASUREMENTS

When servicing the electronic ignition control there are several times when voltages and currents must be measured or observed.

NOTE: All voltages measured will be AC voltage

and all current measured will be DC curĆ rent.

Terminal Terminal Use

1 Pilot valve connection between terĆ

minal #1 and ground

2 Wire from thermostat

3 Main valve connection between terĆ

minal #3 and ground

4 Flame sensor

TABLE 1

To Measure AC Voltages:

1. Set the selector switch on the voltmeter to the AC voltage position.

2. Connect the meter leads in parallel with the voltage to be measured.

To Measure DC Flame Sensing Current:

1. Turn off the power supply to the ignition conĆ trol.

2. Disconnect the flame sensor cable from termiĆ nal #4 on Johnson units or terminal #15 on Landis & Gyr units.

3. Set the selector switch on the meter to microĆ amp scale. Connect the positive (red) lead to terminal #4 and the negative (black) lead to the sensor cable.

4. Disconnect the main valve lead from terminal #3. This will prevent the main burner from ignitĆ ing. A proper measurement of flame sensing current is taken with the pilot light only.

5. Turn the power back on and close the thermoĆ stat contacts. Read the current at the meter.

NOTE: The minimum current required for the

Johnson G770 is 0.15DCmA. The miniĆ mum current required for the Landis & Gyr is 2.0DCmA. (This unit is polarity specific.)

6. Turn the power off to disconnect the meter and reconnect terminal #3 and #4.

To Measure DC Flame Sensing Current Using the Johnson Y99AUĆ3 Signal Transducer:

1. Set the function selector switch to the DC voltĆ age position.

2. Turn off the supply voltage to the control.

3. Disconnect the flame sensor cable from termiĆ nal #4 on the ignition control.

4. Connect the male 1/4" spade connector (-) to the flame sensor cable. Connect the female 1/4" spade connector (+) to terminal #4.

5. Disconnect the main valve lead from terminal #3 on the ignition control.

6. Turn the supply voltage on and close the therĆ mostat contacts to cycle the system.

7. When the pilot lights, read the current on the meter display.

NOTE: The conversion factor is 1DC volt - 1

DC microamp.

3. Read the voltage at the meter.

6-2

Page 85

MT3255 and MT3270

REPAIRING THE ELECTRONIC IGNITION SYSTEM

Flame Sensing Current Maintenance:

The flame sensor is made of carbon steel and subĆ ject to contamination and oxidation buildup. Any buildup on the sensor can add enough resistance to drop the signal below the required minimum. Carbon and oxidation can also build up on the pilot hood. The pilot hood is part of the circuit and must be kept as clean as the flame sensor.

1. Clean the flame sensor with steel wool or an emery cloth.

2. Clean the pilot hood with a small wire brush to remove any carbon or oxidation buildup.

Flame Sensor Replacement:

If the ceramic portion of the flame sensor is broken or if the contamination is extensive, the flame senĆ sor may have to be replaced.

CAUTION!

Shut off all gas to the appliance by closing the shutoff valve in the supply line to that appliance. Disconnect the power supply to prevent electrical shock or possible damage to the equipment.

1. Disconnect the sensing probe cable from the old sensing probe.

2. Remove the old sensing probe from the pilot burner.

3. Check the length of dimension B to be sure the correct replacement probe is being used. See FIGURE 2.

4. Compare the sensing probe rod lengths, diĆ mension A. If required, trim the length of the Y75 rod being installed to the same length as the sensing rod being replaced.

5. Install the Y75 sensing probe into the pilot burner. Reconnect the sensing probe cable. The connections to the sensing probe and control terminal must be secure.

6. Restore the power and the gas supply to the appliance.

7. IMPORTANT: Using a microammeter, check the signal passing through the sensing probe.

8. If the microamp signal is marginal, trim the flame sensing probe in increments of 1/8". Be sure that there is still proper flame impingeĆ ment on the flame sensing probe.

Flame must surround sensing probe tip for approximately 1/2".

9. Observe at least three complete operating cycles to see that all components are functionĆ ing correctly.

Ground Connection

Another important requirement for proper operaĆ tion is the existence of a good electrical ground beĆ tween the pilot assembly and the ignition control. This ground provides the path for sensing current to return to the control, thereby completing the sensing circuit.

In most systems we assume the pilot burner is grounded back to the control through the pilot tubĆ ing and gas valve. The gas valve would be grounded to the ignition control when the control is mounted on the valve. Controls that are not mounted to a gas valve require a separate groundĆ ing wire connecting the control to the pilot assemĆ bly.

In some instances this ground can become weak and cause a low sensing current signal. To assure that a proper ground exists between the control and pilot, a wire can be installed from one of the ground terminals to the pilot bracket. This will asĆ sure a strong ground and maintain a proper sensĆ ing current signal.

FIGURE 2

Using a 1/4" female spade connector, connect one end of the new wire to the ground strip on the igniĆ tion control. Attach the other end of the wire to a bolt or screw on the pilot burner bracket. Be sure to use a wire with a high temperature rated insulaĆ tion.

6-3

Page 86

TECHNICAL APPENDIX

COOKING COMPUTER - TEMPERATURE VS RESISTANCE

T/F Res/Ohms T/F Res/Ohms T/F Res/Ohms T/F Res/Ohms

70 541.12 230 711.43 390 877.15 550 1038.293

75 546.51 235 716.68 395 882.26 555 1043.255

80 551.9 240 721.92 400 887.36 560 1048.212

85 557.28 245 727.16 405 892.46 565 1053.165

90 562.66 250 732.4 410 897.55 570 1058.113

95 568.04 255 737.63 415 902.63 575 1063.057

100 573.4 260 742.85 420 907.72 580 1067.997

105 578.77 265 748.05 425 912.8 585 1072.931

110 584.13 270 753.29 430 917.87 590 1077.862

115 589.48 275 758.5 435 922.94 600 1087.709

120 594.84 280 763.71 440 928.002 605 1092.626

125 600.18 285 768.91 445 933.062 610 1097.539

130 605.53 290 774.11 450 938.118 615 1102.447

135 610.86 295 779.31 455 943.17 620 1107.35

140 616.2 300 784.5 460 948.216 625 1112.249

145 621.52 305 789.68 465 953.259 630 1117.1

150 626.85 310 794.87 470 958.296 635 1122

155 632.17 315 800.04 475 963.33 640 1126.9

160 637.48 320 805.21 480 968.359 645 1131.8

165 642.8 325 810.38 485 973.383 650 1136.7

170 648.1 330 815.54 490 978.403 655 1141.6

175 653.4 335 820.7 495 983.419 660 1146.4

180 658.7 340 825.86 500 988.43 665 1151.3

185 663.99 345 831.01 505 993.436 670 1156.1

190 669.28 350 836.15 510 998.438 675 1161

195 674.57 355 841.29 515 1003.436 680 1165.8

200 679.85 360 846.43 520 1008.429 685 1170.7

205 685.12 365 851.56 525 1013.417 690 1175.5

210 690.39 370 856.69 530 1018.402 695 1180.4

215 695.66 375 861.81 535 1023.381 700 1185.2

220 700.92 380 866.93 540 1028.356

225 706.18 385 872.04 545 1033.327

TABLE 2

6-4

Page 87

MT3255 and MT3270

THERMOELECTRIC VOLTAGE IN ABSOLUTER MILLIVOLTS TYPE J THERMOCOUPLE

F Reading +5F

10 -0.611 -0.473

20 -0.334 -0.195

30 -0.056 0.084

40 0.224 0.365

50 0.507 0.648

60 0.791 0.933

70 1.076 1.220

80 1.363 1.507

90 1.652 1.797

100 1.942 2.088

110 2.233 2.380

120 2.526 2.673

130 2.820 2.967

140 3.115 3.263

150 3.411 3.560

160 3.708 3.857

170 4.006 4.156

180 4.305 4.455

190 4.605 4.755

200 4.906 5.057

210 5.207 5.358

220 5.509 5.661

230 5.812 5.964

240 6.116 6.268

250 6.420 6.572

260 6.724 6.877

270 7.029 7.182

280 7.335 7.488

290 7.641 7.794

300 7.947 8.100

310 8.253 8.407

320 8.560 8.714

330 8.867 9.021

340 9.175 9.329

350 9.483 9.636

F Reading +5F

360 9.790 9.944

370 10.098 10.252

380 10.407 10.561

390 10.715 10.869

400 11.023 11.177

410 11.332 11.486

420 11.640 11.794

430 11.949 12.103

440 12.257 12.411

450 12.566 12.720

460 12.874 12.029

470 13.183 13.337

480 13.491 13.645

490 13.800 13.954

500 14.108 14.262

510 14.416 14.570

520 14.724 14.878

530 15.032 15.186

540 15.340 15.494

550 15.648 15.802

560 15.956 16.110

570 16.264 16.417

580 16.571 16.725

590 16.879 17.032

600 17.186 17.339

610 17.493 17.646

620 17.800 17.953

630 18.107 18.260

640 18.414 18.567

650 18.721 18.874

660 19.027 19.180

670 19.334 19.487

680 19.640 19.793

690 19.947 20.100

TABLE 3

6-5

Page 88

CONVERSION FACTORS

TECHNICAL APPENDIX

COMMON CONVERSION FACTORS

Multiply By To Get

BTU/hr .001054804 MJ/hr

.0002931 kW

.29285 W

BTU/Ft

.0372589 MJ/m

8.905102 kcal/m

MJ/hr 948.0434279 BTU/hr

Mj/m

26,839225 BTU/ft

kW 3414.71732 BTU/hr

.02832 m

.09290304 m

inches 25.40005 mm

feet .3048 meters

PRESSURE CONVERSIONS FACTORS

Multiply By To Get

in/H2O 0.0361 P.S.I.

25.41 mm/H2O

1.868 mm/Hg

.0025 kg/cm

.0025 bar

2.489 mbar

248.9 Pa

.2489 kPa

P.S.I 27.71 in. H2O

2.036 in. Hg

703.1 mm/H2O

51.75 mm/Hg

meters 3.281 feet

pounds .4536 kg

inches W.C. .249082 kPa

2.49082 mbar

kPa 4.01885 inches W.C.

10 mbar

mbar 0.401474 inches W.C.

kW 3.6 Mj/hr

kcal/m

Kwh/m

.1122952 BTU/ft

96.65 BTU/ft

TABLE 4

.0703 kg/cm

.0689 bar

68.95 mbar

6895 Pa

6.895 kPa

TABLE 5

UNIT CONVERSIONS

1F = .5556C

1C = 1.8F

TABLE 6

6-6

Page 89

MT3255 and MT3270

PRESSURE CONVERSION

PRESSURE CONVERSION CHART

in/H2O P.S.I in/Hg mm/H2O mm/Hg kg/cm

1 .0361 .0735 25.41 1.868 .0025 .0025 2.489 248.9 .2489

2 .0722 .1470 50.81 3.736 .0051 .0050 4.978 497.8 .4978

3 .1083 .2205 76.22 5.604 .0076 .0075 7.467 746.7 .7467

4 .1444 .2940 101.62 7.472 .0102 .0099 9.956 995.6 .9956

5 .1804 .3673 127.0 9.335 .0127 .0124 12.44 1244 1.244

6 .2165 .4408 152.4 11.203 .0152 .0149 14.93 1493 1.493

7 .2526 .5143 177.8 13.072 .0178 .0174 17.42 1742 1.742

8 .2887 .5878 203.2 14.940 .0203 .0199 19.90 1990 1.990

9 .3248 .6613 228.6 16.808 .0228 .0224 22.39 2239 2.239

10 .3609 .7348 254.0 18.676 .0254 .0249 24.88 2488 2.488

11 .3970 .8083 279.4 20.544 .0279 .0274 27.37 2737 2.737

12 .4331 .8818 304.8 22.412 .0304 .0299 29.86 2986 2.986

13 .4692 .9553 330.2 24.280 .0330 .0324 32.35 3235 3.235

14 .5053 1.029 355.6 26.148 .0355 .0348 34.84 3484 3.484

bar mbar Pa kPa

15 .5414 1.102 381.0 28.016 .0381 .0373 37.33 3733 3.733

16 .5774 1.176 406.4 29.879 .0406 .0398 39.81 3981 3.981

17 .6136 1.249 431.8 31.752 .0431 .0423 42.31 4231 4.231

18 .6496 1.322 457.2 33.616 .0457 .0448 44.79 4479 4.479

19 .6857 1.396 482.6 35.484 .0482 .0473 47.28 4728 4.728

20 .7218 1.470 508.0 37.352 .0507 .0498 49.77 4977 4.977

21 .7579 1.543 533.4 39.22 .0533 .0523 52.26 5226 5.226

22 .7940 1.616 558.8 41.09 .0558 .0547 54.74 5474 5.474

23 .8301 1.690 584.2 42.96 .0584 .0572 57.23 5723 5.723

24 .8662 1.764 609.6 44.82 .0609 .0597 59.72 5972 5.972

25 .9023 1.837 635.0 46.69 .0634 .0622 62.21 6221 6.221

26 .9384 1.910 660.4 48.56 .0660 .0647 64.70 6470 6.470

27 .9745 1.984 685.8 50.43 .0685 .0672 67.19 6719 6.719

6-7

Page 90

TECHNICAL APPENDIX

in/H2O kPaPambarbarkg/cm

28 1.010 2.056 710.8 52.26 .0710 .0696 69.64 6964 6.964

29 1.047 2.132 736.8 54.18 .0736 .0722 72.19 7219 7.219

30 1.083 2.205 762.2 56.04 .0761 .0747 74.67 7467 7.467

31 1.119 2.278 787.5 57.91 .0787 .0772 77.15 7715 7.715

32 1.155 2.352 812.8 59.77 .0812 .0796 79.63 7963 7.963

33 1.191 2.425 838.2 61.63 .0837 .0821 82.12 8212 8.212

34 1.227 2.498 863.5 63.49 .0862 .0846 84.60 8460 8.460

35 1.263 2.571 888.9 65.36 .0888 .0871 87.08 8708 8.708

36 1.299 2.645 914.2 67.22 .0913 .0896 89.56 8956 8.956

37 1.335 2.718 939.5 69.08 .0938 .0920 92.04 9204 9.204

38 1.371 2.791 964.9 70.95 .0964 .0945 94.53 9453 9.453

39 1.408 2.867 990.9 72.86 .0990 .0971 97.08 9708 9.708

40 1.444 2.940 1016 74.72 .1015 .0996 99.56 9956 9.956

41 1.480 3.013 1042 76.59 .1040 .1020 102.0 10204 10.20

mm/Hgmm/H2Oin/HgP.S.I

42 1.516 3.086 1067 78.45 .1066 .1045 104.5 10452 10.45

43 1.552 3.160 1092 80.31 .1091 .1070 107.0 10701 10.70

44 1.588 3.233 1118 82.18 .1116 .1095 109.5 10949 10.95

45 1.624 3.306 1143 84.04 .1142 .1120 112.0 11197 11.20

46 1.660 3.378 1168 85.90 .1167 .1144 114.5 11445 11.44

47 1.696 3.453 1194 87.76 .1192 .1169 116.9 11694 11.69

48 1.732 3.526 1219 89.63 .1218 .1194 119.4 11942 11.94

49 1.768 3.600 1244 91.49 .1243 .1219 121.9 12190 12.19

50 1.804 3.673 1270 93.35 .1268 .1244 124.4 12438 12.44

51 1.841 3.748 1296 95.27 .1294 .1269 126.9 12693 12.69

52 1.877 3.822 1321 97.13 .1320 .1294 129.4 12941 12.94

53 1.913 3.895 1346 98.99 .1345 .1319 131.9 13190 13.19

54 1.949 3.968 1372 100.8 .1370 .1344 134.4 13438 13.44

55 1.985 4.041 1397 102.7 .1395 .1369 136.9 13686 13.69

56 2.021 4.115 1422 104.6 .1421 .1393 139.3 13934 13.93

TABLE 7

6-8

Blodgett MT3255 Service Manual

Specifications and Main Features

Frequently Asked Questions

User Manual