Blodgett MT3255 Series Installation and operating 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 [phone] Fax: [phone]
PN M8561 Rev B (6/01)
E1999 --- G.S. Blodgett Corporation All rights reserved.
Duplication of the information in this manual is prohibited without the consent of the Blodgett Service Department.

TABLE OF CONTENTS
i
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............................................................
MT-70-PH Domestic --- M2468 Rev E 3---7.............................................
MT-70-PH 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.....................................................
Te m p e r a t u r e 3 --- 2 8..................................................................
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..................................................

TABLE OF CONTENTS
ii
B e l t S p e e d C a li b r a t i o n --- C l o s e d L o o p 4 --- 3...........................................
B e l t S p e e d C a l i b r a t i o n --- O p e n L o op 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 --- 1 5............................................................
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...........................................................
C o o k i n g C o m p u t e r --- Te m p e r a t u r e v s R e s i s t a n c e 6 --- 4....................................
Thermoelectric Voltage in Absoluter Millivolts --- Type J Thermocouple 6---5..................
Conversion Factors 6 --- 6...............................................................
Pressure Conversion 6 --- 7..............................................................

INTRODUCTION
CHAPTER 1

MT3255 and MT3270
1 --- 1
OVEN SPECIFICATIONS
VENTILATION REQUIREMENTS
The hood should completely cover the unit with an
overhang of at least 6” (15 cm) on all sides not adja-
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 1200-1650 2400-3300 3600-5000
M
3
/min 34 - 47 68-93 102-142
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,
1Φ, 208-240VAC, 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, 1Φ, 230 VAC, 3 wire service consisting of L1,
neutral and ground. See FIGURE 1. Use 90_Cwire
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,
3Φ,4 wire service consisting of L1, L2 neutral and
ground. The 415/240 oven requires a 48 Amp,
50Hz, 3Φ,3 wire service consisting of L1, neutral
and ground. See FIGURE 1. Use 90_Cwireand
size wire according to local codes.
U.S. Installations Export Installations --- Gas Models
L1
N
L2
120
120 208-240 OvenSupply
L1
N220-230 OvenSupply
Export Installations --- MT3255E
L1
N
L2
110
110 380/220 OvenSupply
Export Installations --- MT3255E
L1
N415/240 OvenSupply
FIGURE 1

INTRODUCTION
1 --- 2
CE approved installations
Connect the oven to a separate group 230V, 50 hz
with rigid connection and circuit breaker. The cir-
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.
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.
s
Connector 1
2
L3
L2
L1
N
Fan
N
L
Blodgett
Connector
2-4-92
A2
A1
2
1
Relay A
2
1
Air Pressure Regulator
Burner Control Solenoid
MT1828G CE Approved Installations
L1
N230 OvenSupply
FIGURE 2

MT3255 and MT3270
1 --- 3
GAS SPECIFICATIONS
GAS CONNECTIONS
Domestic and General Export installations
The gas line should be large enough to accommo-
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 con-
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), con-
sult the factory.
CE approved installations
1. Connect the oven to the gas line with the prop-
er type of gas according to Local and National
Installation Standards. See TABLE 2.
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 me-
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 M
3
/min of all the appliances.
2. Size the meter accordingly.
DOMESTIC AND GENERAL EXPORT
Natural Gas Propane Gas
Gas Line Sizing
Single
Double
Triple
3/4” line
1-1/4” line
1-1/4” line
3/4” line
1Iline
1-1/4” line
Orifice Size #1 #29
Incoming Gas Pressure W.C. kPa mbar W.C. kPa mbar
Static
Operational
7”
5.5”
1.74
1.36
17.4
13.7
12.5”
11”
3.11
2.73
31.1
27.4
CE APPROVED UNITS
Type of
Gas
Inlet
Pressure
mbars
Burner Pressure
mbars
Injector
Diameter
mm
Air
Opening
mm
Pilot
Injector
mm
Standard
Delivery
Value kW (H
S
)
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
Pressure Regulator
5,15 16 2 x 0,63 46 Nat. Gas
G31 30/37/50 24 3,48 16 2 x 0,30 46 Propane
TABLE 2

INTRODUCTION
1 --- 4
ILLUSTRATED PARTS LISTS
CONVEYOR COMPONENTS
NOTE: n= ASAP Distributor Required Stocking Parts
*=ItemtoolargeforUPS
Ref.
No.
Part
No. Description
Ref.
No.
Part
No. Description
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)
nM2379 Speed Control Board, Bodine
(After 9/90)
nM3142 Speed Control Board, Minarik
(Before 9/90)
n21170 Speed Control Kit, Dart to Mi-
narik
M0705 Speed Control Board, KBIC w/
Pot.
nM2254 Fuse, Line, Bodine Board, 5
AMP, 125V
nM2316 Fuse, Armature, Bodine Board,
200 MA, 250V
nM3145 Potentiometer, Bodine, 10 K
nM3143 Potentiometer, Minarik, 5 K
nM3144 Potentiometer, Dart, 10 K
21169 Knob, Speed Control Poten-
tiometer
nM0200 Lock, Speed Control Poten-
tiometer
nM0201 Dial, Speed Control Potentiom-
eter
nM3146 Time Display, Digital
nM3147 Pick---Up, PV---10 (for M3146)
M3393 Speed Control, Dart Micro---
Drive
nM0984 Pick---Up, PV---2 (for M3393)
M5770 Conversion Kit, Digital Time
(Open Loop) to Micro-Drive
(Closed Loop)
nM3127 Motor, Conv. Drive, Bodine 90V
(Before 9/90)
nM2378 Motor, Conv. Drive, Bodine
130V (After 9/90)
nM2500 Brush Set, Bodine
n21152 Chain, Drive Single Belt (2.33
FT)
M0391 Chain, Drive Twin Belt (Specify
5.50 FT & Order M0112)
nM0112 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
nM0109 Sprocket, Motor Drive, 12 Tooth
(1 Per Motor)
nM0110 Sprocket, Conveyor Drive, 15
Tooth (Qty 1)
M1865 Sprocket, Conveyor Drive, 15
Tooth (TB Qty 1)
nM0108 Sprocket, Conveyor Belt, 11
Tooth (Qty 14 SB) (Qty 16 TB)
21301 Sprocket, High Speed (Large)
nM0122 Bearing, Conveyor Drive

MT3255 and MT3270
1 --- 5
TEMPERATURE CONTROLS
NOTE: n= ASAP Distributor Required Stocking Parts
COMPUTER CONTROLS
Ref.
No.
Part
No. Description
Ref.
No.
Part
No. Description
nM6474 Computer Control Kit, Closed
Loop SB
nFW525 Computer Control Kit, Closed
Loop SB (Reconditioned)
M5635 Computer Control Kit, Open
Loop TB
M3175 Decal, Lexan Control SB
M4400 Decal, Lexan Control TB
nM7427 Probe, Temperature RTD, 500
OHMS
M7202 Conversion Kit, Open Loop to
Closed Loop
nM3347 Cable, Computer Control, 25
Pin, 10’
nM3348 Cable, Computer Control, 9
Pin, 10’
M3490 Cable, Computer Control, 25
Pin, 50’
M3491 Cable, Computer Control, 9
Pin, 50’
nM3349 Harness, Inter---Connecting DC
Drive, 3-Wire (For 9 Pin)
M3353 Harness, Relay Board (Open
Loop)(For25Pin)(Before
9/15/95)
M7237 Harness, Relay Board (Closed
Loop)(For25Pin)(After
9/15/95)
M3314 Bracket, Computer Wall
M5661 Bracket Assy., Cable Clamp
nM0984 Pick---Up, PV---2
M7236 Board, Relay/Transformer
n22672 Relay
nM3352 Transformer, 120V to 24V
nM3295 Thermostat, High Limit (Manual
Reset)
nM0152 Contact, Emergency Stop
Switch
M3296 Activator, Emergency Stop
Switch (Mushroom Shape)
M3297 Nameplate, Emergency Stop
nM3136 Breaker, 7 AMP Circuit
nM2772 Breaker, 4 AMP Circuit
SOLID STATE CONTROLS
Ref.
No.
Part
No. Description
M7982 Controller, Analog Temperature
(Before Mid 1986)
nM3149 Controller, Digital Temperature
(After Mid 1986)
nM3439 Relay, Digital Temp. Controller,
10 AMP, 250V
nM3150 Control Board, Temperature Hi---
Lo Limit
nM3151 Thermocouple, Dual Lead (Be-
fore 9/90)
nM3152 Thermocouple, Single Lead (Af-
ter 9/90)

INTRODUCTION
1 --- 6
ELECTRICAL COMPONENTS
NOTE: n= ASAP Distributor Required Stocking Parts
Ref.
No.
Part
No. Description
Ref.
No.
Part
No. Description
nM2316 Fuse, Armature, Bodine Board,
200 MA, 250V
nM2254 Fuse, Line, Bodine Board, 5
AMP, 125V
nM0156 Fuse, Convection Motor
FNM---10 (Qty 8)
M0702 Fuse Block
nM1821 Fuse, Control SC---4 (Qty 3)
(Before...)
nM0158 Fuse Holder (Qty 3) (Before...)
nM3389 Fuse, Ceramic MDA---4 (Qty 3)
(After...)
nM3390 Fuse Holder (Qty 3) (After...)
nM1362 Snap Disc, L140/20F, 2 Pole
SPST
nM0635 Snap Disc, F110/20F, 2 Pole
SPST
nM2453 Snap Disc, L140/20F, 3 Pole
SPDT (PH)
M0593 Terminal Block, 2 Pole
nM0708 Contactor, 3 Pole, 120V Coil
(Convection)
nM0595 Switch, Air Pressure SPDT
21124 Fan Kit, Axial (Old)
n21134 Fan, Axial 30 CFM 3---1/2”
nM2469 Fan, Axial 110 CFM 4---1/2”
M0571 Guard & Hardware, Fan 4” (Qty
3)
nM0572 Cord, Axial Fan 30” Power
nM0152 Selector Switch, Heat & Convey-
or
nM0153 Selector Switch, Blower
nM0151 Knob, Selector Switch (Heat,
Conveyor or Blower)
M1694 Cord Set & Plug Assy., 10 Foot
M0772 Receptacle, Twist Lock
n16998 Relay, Interlock Hood System
SPST, 120V (PH)
16241 Relay, Alarm 3PDT, 120V (PH)
nM0791 Indicator Light (PH)
CONVECTION COMPONENTS
Ref.
No.
Part
No. Description
nM4224 Motor & Blower Assy., CW
nM4225 Motor & Blower Assy., CCW
nM5722 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.
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