Blodgett MT3240E Service Manual

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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

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TABLE OF CONTENTS

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

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TABLE OF CONTENTS

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CHAPTER 1

INTRODUCTION

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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.

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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

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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 90C 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 90C 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 90C 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.

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INTRODUCTION

MT3240G

120

U.S. and Canadian Installations

General Export Installations

L3 L2 L1

208Ć240

220Ć240

MT3240E

OvenSupply

U.S. and Canadian Installations

415/380

General Export Installations

208Ć240

415/ 380

240/ 220

2Ć4Ć92

OvenSupply

Blodgett

Connector

1 2

MT3240G CE Approved Installations

FIGURE 2

Fan

21Air Pressure Regulator

Burner Control Solenoid

Relay A

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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

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

4,8 8 2 x 0,63 31,7 Nat. Gas

Air

12.5"

11"

Pilot

Injector

3.11

2.73

Standard

Delivery

Value kW (HS)

31.1

27.4

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CHAPTER 2

OPERATION

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MT3240 Series

COMPUTER CONTROLLER

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 180F (82C).

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

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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.

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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).

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Page 15

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.

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Page 16

MT3240 Series

MT3240E DOMESTIC AND GENERAL EXPORT - M4196 REV C

COMPONENT REFERENCE

NOTE: Refer to FIGURE 5 page 2-13 for compoĆ

nent locations.

1. COOKING COMPUTER (FW525)

2. BELT STOP RELAY (22672)

3. BLOWER RELAY (22672)

4. MOTOR CONTACTOR (M0708)

5. CONVECTION FANS

6. SPDT THERMAL SWITCH (M2453 140Ć20F)

7. COOLING FANS (M2469)

8. RTD PROBE (M7427)

9. SPST THERMAL SWITCH (M1362 L140Ć20F)

10. HIGH LIMIT SWITCH (M3295)

11. HEAT RELAY (22672)

12. MERCURY CONTACTOR

13. DC SPEED CONTROL BOARD (M2379)

14. 130 VDC MOTOR (M2378)

OPERATION

1. Apply power to the oven. Program the time and temperature into the computer (1). The belt stop relay (2) and blower relay (3) energize powering up the oven.

2. The blower relay sends 115 volts to the coil of the motor contactor (4) starting the two convection fans (5) in the rear of the oven. Power is also apĆ plied to the N.C. terminal of a SPDT thermal switch (6). 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 (7).

NOTE: The SPDT thermal switch is located in

the cooking computer control compartĆ ment. This switch toggles when the temĆ perature passing its face exceeds the rating on the back of the switch and closes when there is a 10Ć205 drop in temperature across the face of the switch.

3. On a call for heat from the cooking computer, as sensed by an RTD probe (8), the heat relay (11) closes sending 115 VAC to one side of a SPST thermal switch (9). If the switch is closed power goes to one terminal of the manual resettable high

limit switch (10). If this switch is closed 115VAC goes to the coil of a mercury contactor (12).

NOTE: The thermal switch is located in the conĆ

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: When the coil is energized on the conĆ

tactor, mercury is displaced completing a circuit within the contactor, sending power to the heating elements.

NOTE: The RTD probe is located in the rear of

the oven in the convection fan compartĆ ment.

4. The conveyor is driven by an open loop DC control system consisting of a DC speed conĆ trol board (13), a 130 VDC motor (14) 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.

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. The transĆ former is located in the control compartĆ ment.

2-5

Page 17

MT3240G AUSTRALIA - M4174 REV A

OPERATION

COMPONENT REFERENCE

NOTE: Refer to FIGURE 6 page 2-14 for compoĆ

nent locations.

1. COOKING COMPUTER

2. BELT STOP RELAY

3. BLOWER RELAY

4. HEAT RELAY

5. DC SPEED CONTROL BOARD

6. SPST THERMAL SWITCH

7. HI LIMIT SWITCH

8. SPST PRESSURE SWITCH

9. COMBUSTION MOTOR

10. STEP DOWN TRANSFORMER

11. IGNITION CONTROL MODULE

12. PILOT VALVE

13. BURNER VALVE

14. RTD PROBE

15. SPDT PRESSURE SWITCH

16. MOTOR CONTACTOR

17. CONVECTION FANS

18. COOLING FANS

19. SPST THERMAL SWITCH

20. 180VDC MOTOR

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.

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

If the high limit switch is closed power flows to one terminal of a SPST pressure switch (8).

NOTE: This pressure switch senses pressure

from the convection fans. If any of the convection fans fail this switch opens cutting power to the combustion motor.

If the pressure switch is closed, 240 volts is apĆ plied to the combustion motor (9) and a 240/24VAC step down transformer (10). When the step down transformer is powered up, 24 volts to applied to terminal #2 of the ignition control 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. On a call for heat from the cooking computer as sensed by an RTD probe (14), the heat relay closes sending 24 VAC to a SPDT pressure switch (15).

NOTE: This pressure switch senses a vacuum

created by the combustion blower. If the blower fails, the switch toggles beĆ tween deĆenergizing the main valve and illuminating a red indicator light.

2-6

Page 18

MT3240 Series

If the switch is closed, 24 volts is applied to the coil of the main burner valve.

4. The blower relay sends 240 volts to the coil of the motor contactor (16) starting the two conĆ vection fans (17) in the rear of the oven. This contactor also supplies power to the N.C. terĆ minal 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 (18).

NOTE: The SPDT thermal switch is located in

the junction box in the rear of the oven in the blower compartment.

5. The conveyor is driven by an open loop DC control system consisting of a DC speed conĆ trol board, a 180 VDC motor (20) 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 to 180 VDC based on the DAC voltage applied to the board or the time programmed into the computer.

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.

2-7

Page 19

MT3240G CE - M4172 REV C

OPERATION

COMPONENT REFERENCE

NOTE: Refer to FIGURE 7 page 2-15 for compoĆ

nent locations.

1. COOKING COMPUTER (FW525)

2. BLOWER RELAY (22672)

3. BELT STOP RELAY (22672)

4. HEAT RELAY (22672)

5. MOTOR CONTACTOR (M2247)

6. CONVECTION FANS (Clockwise - , CounterĆclockwise - )

7. CONVECTION FAN PRESSURE SWITCH (M0595)

8. DC DRIVE BOARD (M3153)

9. HI LIMIT SWITCH (M3295)

10. DC MOTOR (M3128)

11. SPST THERMAL SWITCH (M1362)

12. SPST RELAY (16775)

13. TPDT RELAY (90250)

14. TEN SECOND TIMER (M3173)

15. DIFFERENTIAL PRESSURE SWITCH (M2819)

16. COMBUSTION BLOWER MOTOR (M2386)

17. LANDIS & GYR IGNITION CONTROL SYSTEM (M3168)

18. 2 SECOND TIMER (M3172)

19. DUAL SOLENOID GAS VALVE (Natural - M6000, LP - M6001)

20. RTD PROBE (M7427)

21. SPDT THERMAL SWITCH (M2453)

22. COOLING FANS (23034)

OPERATION

1. Apply power to the oven. Program the time and temperature into the computer (1). The blower relay (2), belt stop relay (3) and heat relay (4) pull in and power up three separate circuits. The voltage to the relay coils is 12 VDC.

2. The blower relay closes sending 230 volts to the coil of the motor contactor (5). Points 1, 2, 5 and 6 close powering the convection fans (6 & NO TAG).

3. The convection fan pressure switch (7) closes due to the vacuum that is established in the burner tube chamber by the operation of the convection fans.

4. The belt stop relay sends 230 volts to the DC drive board (8) and the manual reset hi limit switch (9). The DC motor (10) starts provided there is a time entered in the cooking computer.

NOTE: The motor used in this oven is 180 volts

DC at its highest speed.

NOTE: This relay will only be powered if there

is a time programmed into the computĆ er. THE OVEN WILL NOT HEAT IF TIME IS NOT PROGRAMMED INTO THE COMPUTER.

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.

5. The heat relay sends 230 volts to a single pole single throw thermal switch (11). If closed the relay continues to send power to one side of a single pole single throw relay (12). This relay will not see power at it's coil until a triple pole double throw relay (13) closes and the ten secĆ ond timer (14) counts down.

6. Once the convection fan pressure switch closes, 230 volts go to a differential pressure switch (15), the combustion blower motor (16), terminal #7 and the coil of the triple pole double throw relay.

7. When a differential is sensed at the differential pressure switch the switch changes position allowing power to go to terminal #9 of the triple pole double throw relay. This relay is a latching

2-8

Page 20

MT3240 Series

relay and is held closed by power that was apĆ plied at terminal #7.

8. Power flows from terminal #8 of the triple pole double throw relay to a ten second purge timer. This timer allows the combustion blower to opĆ erate for ten seconds allowing the combustion chamber to clear of any combustible gasses.

9. After the timer times out the voltage is applied to the other side of the coil of the single pole single throw relay. When that set of contacts closes, voltage goes to terminal #1 of the LanĆ dis & Gyr ignition control system (17). Terminal #8 will send power to one side of a two second timer (18) and the pilot coil of the dual solenoid gas valve (19). After two seconds elapse, the voltage is applied to the main coil of the dual solenoid gas valve. This voltage will remain provided there is a call for heat from the comĆ puter. If proof of flame is strong the ignition sysĆ tem stays powered up. Should the flame signal be lost, the ignition control system will lock out.

NOTE: Cooking computer receives informaĆ

tion from an RTD probe (20) located in front of the combustion blower motor. The information is in the form of resistĆ ance. The resistance ascends as temĆ perature increases.

10. When power is applied to the motor contactor coil voltage is also applied to the NC terminal of a single pole double throw thermal switch (21). This switch in a cold state should be made between NC and common powering up the cooling fan (22) located in the cooking computer compartment.

NOTE: The single pole double throw switch

powers up the cooling fan even if the oven is turned off.

2-9

Page 21

MT3240E CE - M6509 REV C

OPERATION

COMPONENT REFERENCE

NOTE: Refer to FIGURE 8 page 2-16 for compoĆ

nent locations.

1. COMPUTER (FW525)

2. BELT STOP RELAY (22672)

3. BLOWER RELAY (22672)

4. HEAT RELAY (22672)

5. MOTOR CONTACTOR (M0708)

6. SPDT THERMAL SWITCH (M2453 L140-20F)

7. COOLING FANS (M2469)

8. CONVECTION FANS (Clockwise - , CounterĆclockwise - )

9. RTD PROBE (M7427)

10. SPST THERMAL SWITCH (M1362 L140-20F, M2734 L165-30F)

11. MANUAL RESETABLE HIGH LIMIT SWITCH (M3295)

12. HEATING ELEMENT CONTACTOR (R1530)

13. HEATING ELEMENTS (M2573)

14. 130 VDC MOTOR (M2378)

15. #2 HALL EFFECT PICKUP (M0984)

16. DC SPEED CONTROL BOARD (M2379)

17. STEP DOWN TRANSFORMER (M7170)

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. The blower relay closes sending power to the motor contactor (5) and the N.C. terminals a SPDT thermal switch (6). 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.

NOTE: The thermal switch is located in the

junction box in the convection fan compartment.

Two cooling fans (7) are located in the rear of the oven. These cooling fans protect the convection fans from high ambient heat. Two additional cooling fans (7) are located in the computer conĆ trol compartment. These cooling fans protect the controls from high ambient heat.

The motor contactor closes energizing three convection fans (8) in the rear of the oven.

3. On a call for heat from the cooking computer, as sensed by an RTD probe (9), the heat relay closes sending 115 VAC to one terminal of a N.C. SPST thermal switch (10). The switch toggles if the temperature passing its face exĆ ceeds the rating on the back of the switch.

NOTE: The RTD probe is located in the control

compartment. It should be checked with an ohm meter. The SPST thermal switch is located in the rear of the conĆ vection fan compartment.

If the switch is closed, 115 VAC is delivered to one terminal of the manual resetable high limit switch (11). The high limit switch is a bulb and capillary style switch. It reacts when the oven cavity temperature exceeds the high limit proĆ grammed into the cooking computer.

If the manual resetable high limit switch is closed power is sent to the contact coil of the heatIng element contactor (12) energizing the heating elements (13).

4. The conveyor belt is driven by a closed loop D.C. drive system consisting of a 130 VDC moĆ tor (14), a #2 Hall effect pickup (15), a DC speed control board (16) and the DAC located

2-10

Page 22

MT3240 Series

in the cooking computer. The motor speed varĆ ies based on the time programmed into the cooking computer. If time is programmed, a voltage from .3 to 3.8 is applied to the DC speed control board. The output voltage meaĆ sured at terminals A1 and A2 varies from 20 to 130 VDC based on the DAC voltage applied to the board or the time programmed into the computer.

NOTE: The DAC receives 20 VDC from the

speed control board. The DAC returns a portion of the voltage (between .3 and 3.8 VDC). The amount of voltage is dependent on the time programmed into the computer.

NOTE: This type of system does sense the

weight of the product and will not slow down if the belt is fully loaded.

NOTE: The control voltage is supplied by a

240/120 step down transformer (17). The transformer is located in the control compartment.

2-11

Page 23

OPERATION

2 4

1617

1515

FIGURE 4

2-12

Page 24

MT3240 Series

FIGURE 5

2-13

Page 25

OPERATION

FIGURE 6

2-14

Page 26

MT3240 Series

1413

FIGURE 7

2-15

Page 27

OPERATION

FIGURE 8

2-16

Page 28

MT3240 Series

OVEN ADJUSTMENTS FOR COOKING

The combination of belt time, oven temperature, and air flow are important for achieving quality reĆ sults from your Blodgett conveyor oven. Use the following guidelines to adjust the belt time and oven temperature of your unit. For questions reĆ garding further oven adjustments, please contact your local Blodgett Sales Representative for assisĆ tance.

CONVEYOR SPEED AND OVEN TEMPERATURE

Conveyor belt speed (cook time) and oven temperĆ ature are the two variables used when fine tuning your oven for a specific product. To determine the optimum bake time and temperature, make small changes for each trial and keep one variable constant. For example, if the oven temperature is 460F (238C) and the belt speed is 7 minutes, but the pizza is not browned enough, increase the temĆ perature to 475F (246C) and keep the belt speed the same. However, if the center of the pizza is not completely cooked, keep the oven temperature the same, and increase the bake time to 7 minutes and 30 seconds. In general, raise the bake temperĆ ature to increase browning, and lengthen the belt time to increase doneness.

FINISHED PRODUCT TEMPERATURES

Internal temperatures of the cooked products should be measured immediately after the product exits the cooking chamber to ensure a safe food temperature. Internal pizza temperatures should be over 165F (74C). Minimum temperature guideĆ lines vary depending on the food items.

Air flow adjustments may be necessary to fine tune the oven for your particular product. The air plate, located at the top of the baking chamber, contains holes that can be covered using BlockĆoff Plates. The plates can easily be adjusted to regulate the air flow for your particular needs. Use the following guidelines to adjust the BlockĆoff Plates. See NO TAG.

1. Ensure the oven is Off and completely cooled.

2. Remove the upper end plug from the drive side of the oven.

3. Using the supplied air plate hook, pull the air plate out of the oven.

4. Remove the wing nuts, screws, and washers holding the BlockĆoff Plates.

5. Adjust the plates.

6. Replace the wing nuts, screws, and washers to tightly secure the BlockĆoff plates in their new locations. Make a sketch of the final airĆ plate setup for future reference.

NOTE: One or two blockĆoff plates may be left

off entirely if appropriate to obtain the desired results.

7. Replace the air plate.

8. Replace the upper end plug.

The following examples illustrate air flow regulation.

NOTE: The first half of the oven chamber greatly afĆ

fects the initial baking of the product, while the last half largely affects the browning.

AIR FLOW ADJUSTMENTS

Slide the product clearance adjustment plates to the lowest possible setting for your menu items. Lowering the clearance plates will reduce the amount of hot air escaping from the chamber openings.

NOTE: The product clearance adjustment plates

can be found on the SG3240 Series ovens only.

 A good bake time and temperature have been

established, but more top browning is desired. Slide one of the BlockĆoff Plates to uncover a row of holes toward the exit end of the oven.

 The bottom of the pizza is golden brown, but

the top is too dark. Close rows at the exit end of the oven to reduce final browning.

 The center of the pizza is still doughy and the

toppings are not fully cooked. Open up rows at the chamber entrance and close rows at the chamber exit.

2-17

Page 29

CHAPTER 3

CALIBRATION AND

ADJUSTMENT

Page 30

MT3240 Series

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 Blodgett Conveyor 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 rotation amperage draw is approximately 1 amp. If the measured amperage is less than .5, check for proper motor rotation direction.

Slinger

Blower

Motor

Cooling Blade

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.

For standard controls, turn the blower switch to on to record the temperature. Adjust the hi/ lo board if necessary. See page 3-5 for temĆ perature calibration procedure.

BLOWER WHEEL ROTATION

Control

Box

Motor

(Side view)

Motor

FIGURE 1

3-1

Motor #1

(CW)

(Top view)

Control

Box

Motor #2

(CCW)

Page 31

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 maxiĆ mum pressure should not exceed 13" W.C. (32 mbar). The manifold pressure, if measured after the regulator located 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 referĆ ence TABLE 2 on page 1-5 of the Introduction.

Both gas pressures should be measured at the same time with two water manometers. This method will reĆ veal any obstructions in the pipe line or inadequate pipe size.

Water Manometer

Pressure

Ta p

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

Water Manometer

Outlet

Pressure

Ta p

Inlet Pressure

Ta p

Regulator Cap

Regulator Adjustment

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 piĆ lot injector.

4. Install the burner and gas block.

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

6. Adjust gas pressure if necessary. See FIGURE 3.

Regulator

Cap

Water Manometer

Regulator

Adjustment

Pressure Regulator (Some export models)

Gas Pressure Adjustment

Pressure Regulator (CE models)

FIGURE 3

Water Manometer

Pressure Ta p

Water Manometer

3-2

Page 32

MT3240 Series

COMPUTER CONTROLLER CONFIGURATION

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

3-3

Page 33

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.

3-4

Page 34

MT3240 Series

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.

3-5

Page 35

BELT SPEED CALIBRATION

CLOSED LOOP SYSTEM

CALIBRATION AND ADJUSTMENT

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 TIME TIME TIME ENTER to acĆ cess the Belt Speed Calibration mode. The disĆ play flashes INIT.

Belt speed calibration:

1. OVEN LENGTH - Set the length of the conveyĆ or belt to 40.

2. MOTOR RATIO - Set the motor gear ratio to

600.

3. SHAFT TEETH - Set the shaft teeth number to15

4. MOTOR TEETH - Set the motor teeth number to 12.

5. BELT RADIUS - Set the belt radius to 8,893.

NOTE: The values given are estimates. If you

reenter the calibration mode after setĆ ting the belt speed, the belt radius may differ from the table.

6. The display gives a four digit value followed by the letter K. Press ENTER twice to verify the belt time.

Belt speed verification:

1. ENTER TEST TIME - Enter a test time to verify the belt speed. The default setting is 7 minutes.

2. WAIT - 1 second delay before the belt moves.

3. ENTER ACTUAL TIME - Place an object on the belt. Note the time from entrance to exit. Enter the actual measured time.

4. ENTER TEST TIME - If the actual measured time is not within 5 seconds of the test time, reĆ

peat the belt verification test to obtain better accuracy. If the actual measured time is acĆ ceptable, press the CLEAR key to continue the belt speed calibration.

5. MAX/MIN CALC TIME - The control sets the fastest and slowest cook time the user can proĆ gram. This requires a 1 minute delay in the calĆ ibration process.

NOTE: If the control cannot read the shaft enĆ

coder the display reads ERROR then ABORT before exiting belt calibration. Verify the connection of the encoder Restart the belt speed calibration.

6. The display flashes MIN SET TIME? Press the PROG/ENTER key to display the calculated minimum set time. Press the PROG/ENTER key to accept this value or enter a new time with a value higher than the default. Press PROG/ENTER again to accept.

7. The display flashes MAX SET TIME? Press the PROG/ENTER key to display the calculated maximum set time. Press the PROG/ENTER key to accept this value or enter a new time with a value lower than the default. Press PROG/ENTER again to accept.

8. The display reads DONE.

To save the new belt speed:

1. Press ENTER to save the belt speed calibraĆ tion program in the control's memory.

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, the oven will not heat, and the belt will not move.

3-6

Page 36

MT3240 Series

OPEN LOOP SYSTEM - SINGLE BELT

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 TIME TIME TIME ENTER to acĆ cess the Belt Speed Calibration mode. The disĆ play flashes INIT.

Belt speed calibration:

1. The display reads BELT SIZE-?. Enter 40 for the length of the conveyor belt. 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

36 for the belt length. Press the PROG/ENĆ TER 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. Use 300 (3 min). Press the PROG/ENĆ TER 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. Press the PROG/ENTER key to permanently store the calibration values in nonĆvolatile memory (NOVRAM).

NOTE: During these adjustments, pressing the

3-7

Page 37

OPEN LOOP SYSTEM - TWIN BELT

CALIBRATION AND ADJUSTMENT

To enter the calibration mode:

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

2. Press CLEAR 1 2 3 4 5 6 PROG/ENTER. The display flashes ACCES S.

3. Press CLEAR, FRONT BELT, FRONT BELT, FRONT BELT, PROG/ENTER to enter the AcĆ cess mode. The display reads FRONT.

4. Press FRONT BELT to toggle between front and rear belt.

5. The display reads FRONT-INIT-F.

Belt speed calibration:

1. The display reads BELT SIZE-?. Enter 40 for the length of the conveyor belt. Press the PROG/ENTER key.

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

36 for the belt length. Press the PROG/ENĆ TER 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.

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. Use 300 (3 min). Press the PROG/ENĆ TER 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.

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.

3-8

Page 38

MT3240 Series

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

# of burners

BTU per burner

Heating value of Gas

CuFt/Hr

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

27,500

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

3-9

=ą27,500 BTU per burner

=ą30.55 CuFt/hr

=ą27.77 Equiv. CuFt/hr

Page 39

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 4.

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. Refer to NO TAG in the Technical Appendix of this manual.

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 4

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.

3-10

Page 40

MT3240 Series

This page intentionally left blank.

3-11

Page 41

CHAPTER 4

TROUBLESHOOTING

Page 42

MT3240 Series

DC DRIVE SYSTEM

POSSIBLE CAUSE(S) SUGGESTED REMEDY

Symptom #1 - Conveyor Belt will not run

 Oven in OFF mode.

 Loose computer controller cord connection.

 Time not programmed into computer.

 Turn to ON position.

 Adjust and retighten cables and set screws.

 Program in a cook time. See Operation Section

(page 2-2).

 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) Display reads MOTOR.

 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. Note #2 on magnet = 1 pulse per rev. #10 on magnet = 5 pulse per rev.

 Motor brushes worn out.

 Defective conveyor drive motor.

 Defective conveyor drive motor controller.

 Wire from pickup open or misplaced.

 Replace brushes.

 Replace conveyor drive motor.

 Replace conveyor drive motor controller.

 Repair or replace wire.

Symptom #2 - Computer error code MOTOR Ć SPEED Ć ERROR

 Belt speed needs calibration.  See Calibration and Adjustments (page 3-7).

 Voltage from Bodine controller to DAC not presĆ

 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 between

 Replace the computer.

4.7 and .47 VDC (open loop) or 3.5 and .38 (closed loop) when different times are programmed into the cooking computer. Measure the voltage beĆ tween the green and blue wires of the 3 pin conĆ nection.

4-1

Page 43

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

NO TAG) to determine if probe is bad. Replace if necessary.

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.

4-2

Page 44

MT3240 Series

HEATING SYSTEM

POSSIBLE CAUSE(S) SUGGESTED REMEDY

Symptom #1 - Burner will not fire

 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 in combustion burner box 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 NO TAG

through NO TAG).

 Check convection blower (or convection fans) for

proper operation. Verify that tube is clear.

 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 NO TAG) to check the probe. If the probe is alĆ right the computer 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. Unit will not refire if pilot fails to go out when unit is off.

 Verify cooling fan operation and hood system.

 Check hood system.

 Replace valve.

4-3

Page 45

POSSIBLE CAUSE(S) SUGGESTED REMEDY

Symptom #2 - Oven will not reach desired temperature

TROUBLESHOOTING

 Gas pressure to oven is too low.

 Top air plates missing.

 Faulty RTD probe.

 Blower motor(s) running backward.

 Controller out of calibration.

 Excessive food/debris accumulation blocking the

airflow.

Symptom #3 - Burner operates sporadically

 Air pressure switch may be open.

 Verify pressure.

 Install air plates.

 Use the chart in the Technical Appendix (page

NO TAG) to determine if probe is bad. Replace if necessary.

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

place the motor or start capacitor.

 Recalibrate the controller. See Technical AppenĆ

dix (page 3-5).

 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.

 Check convection blower (or 4 convection fans)

for proper operation. Check pressure switch tube for obstructions.

 Thermal switch tripped.

 Faulty RTD probe.

 Excessive food/debris accumulation blocking

the airflow.

 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

NO TAG) to determine if probe is bad. Replace if necessary.

 The inside of the oven should be cleaned to reĆ

4-4

Page 46

MT3240 Series

CONVECTION SYSTEM

POSSIBLE CAUSE(S) SUGGESTED REMEDY

Symptom #1 - Blower motor(s) not running

 Oven in OFF mode.

 Emergency stop switch on OFF.

 No power to oven.

 Motor circuit breaker tripped.

 Faulty start capacitor.

 Motor(s) burnt out.

 Motor contactor open.

 Thermal overload tripped.

 Press ON/OFF key.

 Pull switch out to ON.

 Verify power to motor(s). If there is voltage presĆ

ent, replace the motor. If voltage is not present, check the motor contactor.

 Reset circuit breaker. Determine amp draw.

 Replace capacitor.

 Check draw (3amps or greater).

 Check that the computer is turned on and that a

cook time and temperature have been proĆ grammed. Check for voltage to the coil of the moĆ tor contactor. If voltage is present, replace the contactor. If voltage is not present, check that the blower relay is closed. If not, check for voltage at the blower relay coil. If a 12 VDC voltage is presĆ ent at the coil the blower relay is bad. If there is no voltage present at the coil the computer may need to be replaced.

 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.

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

 Faulty motor contactor.

 Faulty blower motor relay.

 Faulty auxiliary contact (mounted to motor conĆ

tactor).

 Faulty probe.

 Faulty computer.

 Replace contactor.

 If the temperature probe is good check for voltĆ

age at the coil of the blower relay. If voltage is not present the relay is bad. Replace the blower relay.

 Replace auxiliary contactor.

 Check the resistance values of the temperature

probe for values from 135Ć170F (57Ć77C). RefĆ erence NO TAG on page NO TAG of the TechniĆ cal Appendix. If the values do not agree with the chart change the probe.

 If voltage is present at the blower relay, the comĆ

puter is bad. Replace the computer.

4-5

Page 47

TROUBLESHOOTING

POSSIBLE CAUSE(S) SUGGESTED REMEDY

Symptom #3 - Hood system does not operate when oven is on (if interlock is used)

 Fan exhaust/supply problem.

 Defective interlock circuit.

Symptom #4 - Blower motor running backward

 Motor off by thermal overload (other fans forcing

blower to spin).

 Faulty capacitor.

 Contact HVAC service.

 Replace auxiliary contactor.

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

 Replace capacitor.

4-6

Page 48

MT3240 Series

REFERENCE TABLES

HEATING ELEMENT RESISTANCE

Element Resistance

208 volt 3F 2.95-3.27 W

240 volt 3F 3.94-4.35 W

220/380 volt 3F + N 4.96-5.48 W

230/400 volt 3F + N 5.42-5.99 W

PROBE RESISTANCE VS TEMPERATURE

MT3240

200 93 679.2 400 204 886.55

250 121 732.2 450 232 937.70

300 149 784.7 500 260 988.45

350 177 836.75 550 288 1038.7

4-7

Blodgett MT3240E Service Manual

Specifications and Main Features

Frequently Asked Questions

User Manual