Blodgett MT3870 Service And Repair Manual Download Page 57

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TROUBLESHOOTING

5-6

POSSIBLE CAUSE(S)

SUGGESTED REMEDY

Symptom #3 - Hood system does not operate when oven is on

Fan exhaust/supply problem.

Defective interlock circuit.

Contact HVAC service.

Replace auxiliary contactor.

Symptom #4 - Blower motor running backward

Motor off by thermal overload (other fans forcing

blower to spin).

Faulty capacitor.

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.

Replace capacitor.

Summary of Contents for MT3870

Page 1: ...com 50 Lakeside Avenue Box 586 Burlington Vermont 05402 USA Telephone 802 658 6600 Fax 802 864 0183 PN M7489 Rev B 6 01 1996 G S Blodgett Corporation All rights reserved Duplication of the informatio...

Page 2: ...ns 2 2 Mount Remote Control 2 2 False Front If Applicable 2 2 3 OPERATION Computer Controller 3 1 Control Description 3 1 Control Operation 3 1 Programming Procedures 3 2 Display Information 3 2 Seque...

Page 3: ...e 4 12 5 TROUBLESHOOTING DC Drive System 5 1 Computer Control System 5 2 Heating System 5 3 Convection System 5 5 6 TECHNICAL APPENDIX Intermittent Ignition System 6 1 Principles of Operation 6 1 Serv...

Page 4: ...he 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 PROG ENTER KEY Used to...

Page 5: ...fans will con tinue to run until the oven cools to a safe temperature OVEN SHUT DOWN Turn the Computer Controller off press and mo mentarily hold the ON OFF key Since the Cool Down circuit is already...

Page 6: ...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 DISPLAY INFORMATION WAIT LOW indicates th...

Page 7: ...INTRODUCTION CHAPTER 1...

Page 8: ...1 Use 90 C wire and size to National Electric or local codes Installations outside the U S The MT3870 requires a 15 Amp 50Hz 1F 230 VAC 3 wire service consisting of L1 neutral and ground See FIGURE 1...

Page 9: ...our 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 natu...

Page 10: ...Bracket Assy Cable Clamp Qty 1 3 M0984 Pick Up PV 2 Qty 1 After 9 15 95 4 M7236 Board Relay Transformer Qty 1 5 22672 Relay Control Qty 4 6 M3352 Transformer 120V to 24V Qty 1 7 20349 Buzzer 120V Qty...

Page 11: ...Drive Order SB Spec ify 2 FT or TB Specify 4 FT M0112 M0112 Masterlink Drive Chain Qty 1 M6791 Guard Drive 26 Chain SB Qty 1 M6482 Guard Drive Chain TB Qty 1 M3981 Conveyor Before Assy Drive SB MT387...

Page 12: ...Hold Down Nozzle MT3855G Qty 1 Before 11 14 95 M7380 Hold Down Nozzle MT3855G Qty 1 After 11 15 95 36 M3106 Diverter Air LH RH MT3870 Qty 2 M3106 Diverter Air LH RH MT3855G Qty 2 Before 11 14 95 M5179...

Page 13: ...1 3 8 Close Qty 3 or CE Qty 2 55 M0280 Tee 3 4 x 3 4 x 1 4 Qty 1 56 M0278 Bushing 1 4 x 1 8 Hex Qty 2 57 M0281 Plug Pipe 1 8 Black Qty 2 58 17874 Ell Black 1 2 x 3 4 Qty 1 59 M0590 Nipple Pipe 1 2 x 2...

Page 14: ...gle Set of 4 14444 Casters Cradle Triple Oven Set of 4 77 M3783 Stop Product S S Qty 1 78 M3779 Extension Assy Product 6 Qty 1 M4223 Extension Assy Product 10 Qty 1 M7575 Extension Assy Product 15 LaR...

Page 15: ...ty 1 Before 11 14 95 M6799 Control Box Cover w Access Door MT3855G Qty 1 After 11 14 95 XXXXX Control Box Cover w Louvers MT3870 Qty 1 Before 9 15 95 86 M7266 Control Box Cover w Access Door MT3870 Qt...

Page 16: ...ty 1 CE 105 M2386 Blower Motor Combustion Qty 1 CE 106 M7333 Pilot Burner Ignitor Assy LP Qty 1 CE 106 M7334 Pilot Burner Ignitor Assy Nat Qty 1 CE 107 M2497 Switch Push Button Qty 1 CE 108 M2498 Swit...

Page 17: ...INTRODUCTION 1 10 MT3870 DOMESTIC GENERAL EXPORT CONTROL BOX Control Plate and or Gas Burner Components not Shown...

Page 18: ...MT3870 1 11 MT3870 CE CONTROL BOX Control Plate and or Gas Burner Components not Shown...

Page 19: ...INTRODUCTION 1 12 MT3870 DOMESTIC GAS BURNER COMPONENTS Control Box not Shown...

Page 20: ...MT3870 1 13 MT3870 CE GAS BURNER COMPONENTS Control Box not Shown...

Page 21: ...INTRODUCTION 1 14 MT3870 DOMESTIC GENERAL EXPORT SB CONTROL PLATE ASSY M6590...

Page 22: ...MT3870 1 15 MT3870 CE SB CONTROL PLATE ASSY M6589...

Page 23: ...INTRODUCTION 1 16 MT3870 EXTERIOR OVEN VIEW...

Page 24: ...MT3870 1 17 This page intentionally left blank...

Page 25: ...ASSEMBLY CHAPTER 2...

Page 26: ...3 Install the alignment bolt through the conveyor and control box 4 Slide the idle side conveyor rack assembly into the support tracks from the exit end of the oven WIRE CONVEYOR BELT NOTE The conveyo...

Page 27: ...or and the control box AIR PLATES Verify that the proper air plates were received In spect the orientation of the air plates Refer to FIGURE 4 NOTE Standard air plates shown Alternate plates available...

Page 28: ...MT3870 2 3 This page intentionally left blank...

Page 29: ...OPERATION CHAPTER 3...

Page 30: ...uld you need to stop the belt fans or heat press the emergency switch Do not use the emergency switch as a GENERAL on off switch CONTROL OPERATION To turn the oven on 1 Press and hold the ON OFF key 2...

Page 31: ...in memory 3 The display will flash WAIT LOW SET TIME mmss until the programmed bake tempera ture is reached The HEAT lamp 9 will remain lit until the oven reaches the temperature set point 4 The displ...

Page 32: ...e convection fan pressure switch 8 will close only if the convection fans are operating and putting a positive pressure on the switch When this switch closes power goes to the pri mary side of the tra...

Page 33: ...OPERATION 3 4 1 1 2 3 4 5 19 18 13 15 14 6 7 8 9 11 10 12 16 17 17 17 17 FIGURE 2...

Page 34: ...ay 10 This relay will not see power at it s coil until a triple pole double throw relay 11 closes 6 Once the convection fan pressure switch 4 closes 230 volts go to a differential pressure switch 12 t...

Page 35: ...OPERATION 3 6 11 14 13 12 9 7 8 5 4 16 15 17 10 6 2 1 3 3 3 3 FIGURE 3...

Page 36: ...ular needs The area below the belt has all air flow holes open Here are some suggestions for setting up the air flow Keep in mind that the first half of the oven is used for the initial baking of the...

Page 37: ...CALIBRATION AND ADJUSTMENT CHAPTER 4...

Page 38: ...mperage draw is approximately 1 amp If the measured amperage is less than 5 check for proper motor rotation direction TO CHECK LOW LIMIT 1 Turn the oven on and let it heat up to approxi mately 200 F 9...

Page 39: ...ower the gas pressure Be sure to reinstall the screw cap should the diaphragm rupture this cap acts as a flow limiter The air shutter disc on the burner blower motor lo cated inside the control box at...

Page 40: ...ey the display will cycle on to the next screen If a step is missed press the CLEAR button to backup DISPLAY ACTION TAKEN DISPLAY ACTION TAKEN F CMODE Press PROG ENTER T F C Press again or hit any num...

Page 41: ...ENTER 10 F Press PROG ENTER TEMP BOOST STAGE2 TIME Press PROG ENTER 7 SEC Press PROG ENTER TEMP BOOST STAGE2 TEMP Press PROG ENTER 10 F Press PROG ENTER TEMP BOOST STAGE3 TIME Press PROG ENTER 10 SEC...

Page 42: ...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 AC...

Page 43: ...easured time 4 ENTER TEST TIME If the actual measured time is not within 5 seconds of the test time re peat the belt verification test to obtain better accuracy If the actual measured time is ac cepta...

Page 44: ...art 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 dis...

Page 45: ...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 m...

Page 46: ...st be made quickly Low Speed Motor Adjustment For closed loop systems the computer automaticl ly proceeds to low speed For open loop systems continue Belt Speed Calibration through STEP 3 see page 4 7...

Page 47: ...tment Test Points Maximum Speed Minimum Speed Acceleration Adjustment ACC MAX MIN TORQ Socket J1 Line Fuse FL REG L N A1 A2 TB1 Speed Pot Yellow or Violet pin 12 Blue pin 8 Torque current limiting adj...

Page 48: ...ct your local gas sup plier for values Use the following formulas to calculate the correct orifice 1 Firing rate of burners BTU per burner 2 BTU per burner Heating value of Gas CuFt hr 3 CuFt Hr Speci...

Page 49: ...accepted heating val 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 det...

Page 50: ...MT3870 4 13 This page intentionally left blank...

Page 51: ...TROUBLESHOOTING CHAPTER 5...

Page 52: ...oblem Replace fuse Determine amp draw Replace fuse Determine amp draw Verify the unit is set for a single pulse pickup If not reset for a single pulse pickup If yes reattach the pickup Replace brushes...

Page 53: ...e controller has been programmed the computer may need to be replaced Tighten connections Use the chart in the Technical Appendix page 6 10 to determine if probe is bad Replace if necessary Symptom 2...

Page 54: ...t breaker Check transformer for primary and secondary voltage Check main control and burner valve relays to see if closed Check relay in combustion burner box If bad re place relay Set to desired temp...

Page 55: ...he conveyor belt conveyor belt supports and the nozzles The oven interior and all parts re moved should then be cleaned with an appropri ate oven cleaner safe for aluminum Symptom 3 Burner operates sp...

Page 56: ...VDC voltage is pres 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 oper ating If no...

Page 57: ...Symptom 4 Blower motor running backward Motor off by thermal overload other fans forcing blower to spin Faulty capacitor Determine if the cooling blower or fans are oper ating If not verify voltage to...

Page 58: ...MT3870 5 7 This page intentionally left blank...

Page 59: ...TECHNICAL APPENDIX CHAPTER 6...

Page 60: ...ontrol through the flame sensor cable to the flame sensor As the current is conducted through the flame to the pilot hood it is rectified from AC to DC because of the difference in surface area The pi...

Page 61: ...r supply to the ignition con trol 2 Disconnect the flame sensor cable from termi nal 4 on Johnson units or terminal 1 on Lan dis Gyr units 3 Set the selector switch on the meter to micro amp scale con...

Page 62: ...be secure 6 Restore the power and the gas supply to the appliance 7 IMPORTANT Using a microammeter check the signal passing through the sensing probe 8 If the microamp signal is marginal trim the fla...

Page 63: ...8 2 Filter Trough Receptacle 9 2 Filter 10x16 10 2 Filter 10 x 20 11 1 Vertical Exhaust Manifold Right 12 1 Vertical Exhaust Manifold Left 13 1 Cooling Fan Exhaust Enclosure 14 1 Upper Exhaust Enclos...

Page 64: ...nd with hot soapy water Do not use scouring pads plastic or metal on the exterior surfaces as they will scratch and mar the exterior finish Rinse the panels in warm water and dry them 5 Reinstall the...

Page 65: ...ESS For servicing the oven disconnect the gas and electric services from the oven Use the following procedure to move the oven ventilation system as sembly for maintenance 1 Release the over center la...

Page 66: ...37 2737 2 737 12 4331 8818 304 8 22 412 0304 0299 29 86 2986 2 986 13 4692 9553 330 2 24 280 0330 0324 32 35 3235 3 235 14 5053 1 029 355 6 26 148 0355 0348 34 84 3484 3 484 15 5414 1 102 381 0 28 016...

Page 67: ...40 1 444 2 940 1016 74 72 1015 0996 99 56 9956 9 956 41 1 480 3 013 1042 76 59 1040 1020 102 0 10204 10 20 42 1 516 3 086 1067 78 45 1066 1045 104 5 10452 10 45 43 1 552 3 160 1092 80 31 1091 1070 10...

Page 68: ...5 mm feet 3048 meters meters 3 281 feet pounds 4536 kg inches W C 249082 kPa 2 49082 mbar kPa 4 01885 inches W C 10 mbar mbar 0 401474 inches W C kW 3 6 Mj hr kcal m3 1122952 BTU ft3 Kwh m3 96 65 BTU...

Page 69: ...290 774 11 450 938 118 615 1102 447 135 610 86 295 779 31 455 943 17 620 1107 35 140 616 2 300 784 5 460 948 216 625 1112 249 145 621 52 305 789 68 465 953 259 630 1117 1 150 626 85 310 794 87 470 958...

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