Blodgett MT3240E Service Manual
MT3240 SERIES
CONVEYOR OVENS
SERVICE AND REPAIR MANUAL
BLODGETT OVEN COMPANY
www.blodgett.com
50 Lakeside Avenue, Box 586, Burlington, Vermont 05402 USA Telephone (802) 658Ć6600 Fax: (802)864Ć0183
PN M9911 Rev C (11/01)
2001 - G.S. Blodgett Corporation
TABLE OF CONTENTS
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ii
TABLE OF CONTENTS
1. INTRODUCTION
Oven Specifications 1-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Ventilation Requirements 1-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electrical Specifications 1-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Gas Specifications 1-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2. OPERATION
Computer Controller 2-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Sequence of Operation 2-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MT3240G Domestic and General Export - M4193 Rev C 2-3. . . . . . . . . . . . . . . . . . . . . . . . . .
MT3240E domestic and General Export - M4196 Rev C 2-5. . . . . . . . . . . . . . . . . . . . . . . . . . .
MT3240G Australia - M4174 Rev A 2-6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MT3240G CE - M4172 Rev C 2-8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MT3240e CE - M6509 Rev C 2-10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Oven Adjustments for Cooking 2-17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3. CALIBRATION AND ADJUSTMENT
Convection Blower Motors 3-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Regulated Gas Pressure 3-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Computer Controller Configuration 3-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Temperature Calibration 3-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Belt Speed Calibration 3-6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Closed Loop System 3-6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Open Loop System - Single belT 3-7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Open Loop System - Twin Belt 3-8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Rerating the Appliance 3-9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Checking the Firing Rate 3-10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4. TROUBLESHOOTING
DC Drive System 4-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Computer Control System 4-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Heating System 4-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Convection System 4-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Reference Tables 4-7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Heating Element Resistance 4-7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Probe Resistance vs Temperature 4-7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
i
TABLE OF CONTENTS
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CHAPTER 1
INTRODUCTION
MT3240 Series
OVEN SPECIFICATIONS
VENTILATION REQUIREMENTS
A mechanically driven ventilation system is reĆ
quired for the removal of excess heat and cooking
vapors. For gas models, a ventilation system is
also required for the removal of the products of gas
combustion. The necessity for a properly designed
and installed ventilation system cannot be over
emphasized.
The following are general recommendations and
guidelines for good ventilation. Your specific apĆ
plication may require the services of a ventilation
engineer or consultant
The ventilation hood must work well with the building
heating, ventilation and air conditioning (HVAC) sysĆ
tem. The hood exhaust and the supply air flows
should be sized appropriately. Supply air must be
provided by either the hood system or the building
HVAC system in order to prevent a negative presĆ
sure in the oven area. Supply air should replace
approximately 80% of the air flow exhausted by the
hood. The table below can be used as a guideline,
but the correct air flow values depend on the effiĆ
ciency of the hood design, the amount of air flow
around the oven, and the current air flow in and out
of the kitchen or oven area (for existing facilities).
SINGLE DOUBLE TRIPLE
Exhaust Volume - CFM (M3/min)
800Ć1000
(23Ć28)
Supply Requirements - CFM (M3/min)
640Ć800
(18Ć23)
Ideally, supply air is provided through the building
HVAC system or, secondly, through the hood with an
inĆline tempering unit. Air supplied directly from outĆ
side the building to the kitchen or oven area, nonĆ
1200Ć1600
(34Ć46)
960Ć1280
(27Ć36)
TABLE 1
2000Ć2400
(57Ć68)
1600Ć1920
(46Ć54)
tempered, can be used as supply air but the design
must accommodate potential operational and enviĆ
ronmental drawbacks.
NOTE: In NO case should supply air blow at or
near the cooking chamber openings as
that would adversely affect the cooking
consistency and the reliability of the oven.
The hood should be sized to completely cover the
equipment plus an overhang of at least 6" (15cm)
on all sides not adjacent to a wall. The distance
from the floor to the lower edge of the hood should
not exceed 7' (2.1m). See FIGURE 1.
U.S. and Canadian installations
Refer to your local ventilation codes. Requirements
may vary by city, county, province or state. In the
absence of local codes, refer to the National venĆ
tilation code titled, Standard for the Installation of
Equipment for the Removal of Smoke and Grease
Laden Vapors from Commercial Cooking EquipĆ
ment", NFPAĆ96ĆLatest Edition.
General export installations
Installation must conform with Local and National
installation standards. Local installation codes
and/or requirements may vary. If you have any
questions regarding the proper installation and/or
operation of your Blodgett oven, please contact
your local distributor. If you do not have a local disĆ
tributor, please call the Blodgett Oven Company at
0011Ć802Ć860Ć3700.
WARNING:
Failure to properly vent the oven can be hazardĆ
ous to the health of the operator and may result
in operational problems, unsatisfactory baking
and possible damage to the equipment.
Damage sustained as a direct result of improper
ventilation will not be covered by the ManufacturĆ
er's warranty.
1-1
0" (0cm) if wall or
6" (15.2 cm)
INTRODUCTION
3" (7.6 cm)
Minimum
6" (15 .2cm)
Minimum
77" (196 cm)
72" (182 cm)
24"
(61 cm)
14"
(35.5 cm)
Triple Stack - 7" (17.8 cm)
Double Stack - 17.25" (43.8 cm)
Single Stack - 23.25" (59 cm)
SG3240 Series Shown
6" (15.2 cm)
Minimum
FIGURE 1
1-2
MT3240 Series
ELECTRICAL SPECIFICATIONS
MT3240G
U.S. and Canadian installations
The MT3240G requires a 15 Amp, 60HZ, 1F,
208Ć240VAC, 4 wire service consisting of L1, L2,
neutral and ground. Wiring from the power source
to these units must be a minimum of #16 AWG CU.
stranded wire or larger.
Single phase units MUST NOT be connected to the
high leg of a three phase system. The high leg reĆ
fers to a potential of 240 volts between one phase
and neutral. The remaining two legs have a potenĆ
tial of 120 volts between each phase and neutral.
General export installations
The MT3240G requires a 15 Amp, 50Hz, 1F,
220Ć240 VAC, 3 wire service consisting of L1, neuĆ
tral and ground. Use 90C wire and size wire acĆ
cording to local codes.
CE Approved installations
Connect exhaust fan connector 1 and 2. See
FIGURE 2.
Connect phase + neutral + ground .
MT3240E
U.S. and Canadian installations
The MT3240E requires a 80 amp, 60 HZ, 3F,
208Ć240 VAC 4 wire service consisting of L1, L2, L3,
and ground. Use 90C wire and size to National
Electric or local codes.
General export installations
The MT3240E requires a 56 amp, 50 HZ, 3F,
220Ć240 VAC, 4 wire service consisting of L1, L2, L3
and ground. Use 90C wire and size to National
Electric or local codes.
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.
Connect L1 + L2 + L3 + neutral + ground.
THE BLODGETT OVEN COMPANY CANNOT ASĆ
SUME RESPONSIBILITY FOR LOSS OR DAMAGE
SUFFERED AS A RESULT OF IMPROPER INSTALĆ
LATION.
WARNING!!
Incorrect single phase wiring may result in exĆ
tensive damage to electrical components and
fire in the electrical box.
1-3
INTRODUCTION
MT3240G
L1
120
N
120
L2
U.S. and Canadian Installations
L1
N
General Export Installations
L3
L2
L1
N
208Ć240
220Ć240
MT3240E
L1
L2
OvenSupply
OvenSupply
L3
U.S. and Canadian Installations
L1
415/380
L2
415/380
L3
N
General Export Installations
208Ć240
415/
380
240/
220
2Ć4Ć92
OvenSupply
OvenSupply
Blodgett
Connector
N
L
Connector
1
2
MT3240G CE Approved Installations
FIGURE 2
Fan
s
2
A2
21Air Pressure Regulator
Burner Control Solenoid
A1
Relay A
1
1-4
MT3240 Series
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 both the MT3240G is 100,000
BTU/Hr. (29.3 kW/Hr.) (105 MJ/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 #X #X
Incoming Gas Pressure W.C. kPa mbar W.C. kPa mbar
Static
Operational
CE APPROVED UNITS
Type of
Gas
G25 25 12 4,8 8 2 x 0,63 31,7 Nat. Gas
G20 20 8 4,8 8 2 x 0,63 31,7 Nat. Gas
G20/G25 20/25 Totally Inscrewed
G30 30/50 17 2,8 8 2 x 0,30 31,7 Butane
G31 30/37/50 24 2,8 8 2 x 0,30 31,7 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
4,8 8 2 x 0,63 31,7 Nat. Gas
Air
mm
12.5"
11"
Pilot
Injector
mm
3.11
2.73
Standard
Delivery
Value kW (HS)
31.1
27.4
1-5
CHAPTER 2
OPERATION
MT3240 Series
COMPUTER CONTROLLER
9
1
2
3
45678
FIGURE 3
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
180F (82C).
Do not use the emergency switch as a
GENERAL on/off switch!
2-1
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.
2-2
MT3240 Series
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.
MT3240G DOMESTIC AND GENERAL EXPORT - M4193 REV C
COMPONENT REFERENCE
NOTE: Refer to FIGURE 4 page 2-12 for compoĆ
nent locations.
1. COOKING COMPUTER (FW525)
2. BELT STOP RELAY (22672)
3. BLOWER RELAY (22672)
4. HEAT RELAY (22672)
5. DC SPEED CONTROL BOARD (M2379)
6. SPST THERMAL SWITCH (M1362 L140Ć20F,
M2734 L163Ć30F)
7. HI LIMIT SWITCH (M3295)
8. 115/24 STEP DOWN TRANSFORMER (M2381)
9. COMBUSTION MOTOR (22132)
10. CENTRIFUGAL SWITCH
11. IGNITION MODULE (M1054)
12. PILOT VALVE (LP - 22190, Natural - M5495)
13. BURNER VALVE (LP - 22190, Natural - M5495)
14. MOTOR CONTACTOR (M0708)
15. CONVECTION FANS
16. SPDT THERMAL SWITCH (M3453 L140Ć20F)
17. COOLING FANS (M2469)
18. RTD PROBE (M7427)
19. 130 VDC MOTOR (M2378)
20. 240/120 STEP DOWN TRANSFORMER
(M2352)
OPERATION
1. Apply power to the oven. Program the time and
temperature into the computer (1). The belt
stop relay (2), blower relay (3) and the heat
relay (4) energize powering up the oven.
2. When the belt stop relay closes, 120 VAC goes
to the DC speed control board (5) and one terĆ
minal of a SPST thermal switch (6). If switch is
closed, power goes to the manual resetable hi
limit switch (7).
NOTE: The high limit switch is a bulb and capĆ
illary style switch. It reacts when the
oven cavity temperature exceeds the
high limit programmed into the cookĆ
ing computer.
NOTE: The thermal switch is located in the conĆ
trol compartment. This switch opens
when the face of the switch sees 1405F
and closes when there is a 10Ć205 drop
in temperature across the face of the
switch. The switch interrupts the heat
circuit.
If the high limit switch is closed power flows to
the primary side of a 115/24 volt step down
transformer (8) and the combustion motor (9)
of the flame blower. The combustion motor
powers up. When the combustion motor
reaches full speed, a centrifugal switch (10)
closes sending 24 VAC to the ignition module
(11). After the module's self diagnostics are
complete, the pilot valve (12) opens. A proof of
flame allows the burner valve (13) to cycle on
and off for every call for heat.
3. The blower relay sends 115 volts to the coil of
the motor contactor (14) starting the two conĆ
vection fans (15) in the rear of the oven. This
contactor also supplies power to the N.C. terĆ
minal of a SPDT thermal switch (16). 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 (17).
2-3
NOTE: The SPDT thermal switch is located in
the junction box in the rear of the oven
in the blower compartment.
4. On a call for heat from the cooking computer
as sensed by an RTD probe (18), the heat relay
closes sending 24 VAC to the burner valve.
This valve opens sending gas to the flame
blower for ignition.
NOTE: The RTD probe is located in the back of
the oven in the convection fan compartĆ
ment. It should be checked with an ohm
meter.
5. The conveyor is driven by an open loop DC
control system consisting of a DC speed conĆ
trol board, a 130 VDC motor (19) and the DAC
located in the cooking computer. If a time is
programmed into the cooking computer, a
voltage ranging between .47 and 4.7 is applied
to the DC speed control board. The output voltĆ
age measured at A1 and A2 of the board to the
motor varies from 20 to130 VDC based on the
DAC voltage applied to the board or the time
programmed into the computer.
OPERATION
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: The control voltage is supplied by a
240/120 step down transformer (20). The
transformer is located in the control
compartment.
2-4
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