Blodgett MT3255 Service Manual

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.

 1999 - G.S. Blodgett Corporation All rights reserved.

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. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

i

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. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ii

CHAPTER 1

INTRODUCTION

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.

L1

N

L2

120

120

208Ć240

U.S. Installations Export Installations - Gas Models

L1

N

L2

110

110

380/220

Export Installations - MT3255E

OvenSupply

OvenSupply

FIGURE 1

L1

N

L1

N

220Ć230

415/240

OvenSupply

OvenSupply

Export Installations - MT3255E

1-1

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.

L3

L2

L1

N

Blodgett

Connector

N

L

Connector

L1

N

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

A1

Relay A

1

Fan

s

2

A2

21Air Pressure Regulator

Burner Control Solenoid

MT1828G CE Approved Installations

FIGURE 2

1-2

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

7"

5.5"

mbars

3/4" line

1Ć1/4" 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

mm

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

Air

mm

12.5"

11"

Pilot

Injector

mm

3.11

2.73

Standard

Delivery

Value kW (HS)

31.1

27.4

1-3

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

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

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

3)

M0572 Cord, Axial Fan 30" Power

M0152 Selector Switch, Heat & ConveyĆ

or

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

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

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

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

MT3255E GENERAL EXPORT CONTROL BOX

(Control Plate not shown)

INTRODUCTION

1-10

MT3255 and MT3270

MT3255G AND MT3270 DOMESTIC & GENERAL EXPORT CONTROL BOX

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

1-11

INTRODUCTION

MT3255 AND MT3270 CE CONTROL BOX

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

1-12

MT3255 and MT3270

MT3255 AND MT3270 DOMESTIC GAS BURNER COMĆ

PONENTS

(Control Box not Shown)

1-13

INTRODUCTION

MT3255 AND MT3270 CE GAS BURNER COMPONENTS

(Control Box not Shown)

1-14

MT3255 and MT3270

MT3255 AND MT3270 DOMESTIC & GENERAL EXPORT SB CONTROL

PLATE ASSY

1-15

INTRODUCTION

MT3255 AND MT3270 CE SB CONTROL PLATE ASSY

1-16

MT3255 and MT3270

MT3255 AND MT3270 EXTERIOR OVEN VIEW

1-17

CHAPTER 2

ASSEMBLY

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

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

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

CHAPTER 3

OPERATION

MT3255 and MT3270

STANDARD CONTROL OPTIONS

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

1 53 42

COOK TIME

ON OFF

TEMPERATURE

7

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.

6

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