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Pratica Chef Express, Service Manual

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Pratica Chef Express Service Manual Download Page 30

24 

 

 

THEORY OF OPERATION 

How do the microwaves heat the food? 

The  food  is  formed by bipolar  molecules, that  is,  they  possess  a  positive and  a negative pole.  For 
example, water in its composition has hydrogen and oxygen which are positive and negative. 

 

 

 

 

In normal circumstances, the bipolar molecules of a food are disorderly placed. As we know, equal 
charges repel each other, and different charges attract each other, so when a food is exposed to an 
electromagnetic field, the molecules are all aligned so that their charges point at the same direction. 

 

 

 

 

 
When the electromagnetic field inverts the polarity, the molecules also have their directions inverted. 
As the microwaves invert their polarity 2 billion and 450 million times per second, the molecules will 
also vibrate at the same frequency, hitting one another, resulting in friction and production of heat. 

 

 

 

 

 

Water molecule

 

Food molecules under 

normal circumstances 

Food molecules under 

electromagnetic field 

Polarity inverse of the 

electromagnetic field 

Summary of Contents for Chef Express

Page 1: ...Pratica Products Inc USA 675 Town Square Boulevard Suite 200 2018 Pratica Products Inc USA Garland TX 75040 December 2018 For the Chef Express Oven Service Manual ...

Page 2: ...N DIMENSIONS 7 INSTALLATION INSTRUCTIONS 7 UNPACKING INSTRUCTIONS 7 INSTALLATION WARNINGS PLEASE READ BEFORE LIFTING OVEN TO PREVENT INJURY 8 GENERAL INSTRUCTIONS 9 PRECAUTIONS TO AVOID POSSIBLE EXPOSURE TO EXCESSIVE MICROWAVE ENERGY 9 DAILY CLEANING QUARTERLY MAINTENANCE 11 DAILY CLEANING 12 QUARTERLY MAINTENANCE 15 THEORY OF OPERATION 19 CHEF EXPRESS TECHNOLOGY 20 CHARACTERISTICS OF MICROWAVES 2...

Page 3: ...TCH ADJUSTMENTS 53 COMPONENTS 55 MICROWAVE SEALS AND GASKETS 66 TESTING FOR MICROWAVE LEAKAGE 68 IMPINGEMENT SYSTEM 69 BLOWER MOTOR 70 TESTING BLOWER MOTOR 70 FREQUENCY INVERTER WEG CFW 100 71 FREQUENCY INVERTER TROUBLESHOOTING 72 HIGH LIMIT THERMOSTAT 75 TESTING HIGH LIMIT THERMOSTAT 75 CONVECTION HEATER 76 TESTING CONVECTION HEATER 76 IR ELEMENT 77 TESTING IR ELEMENT 77 CC IR TEMPERATURE SENSORS...

Page 4: ... 95 VENT CATALYST 95 CHEF EXPRESS SCHEMATICS 97 CONTROL BOARD SCHEMATIC 98 HEATER SCHEMATIC 99 MICROWAVE CIRCUIT SCHEMATIC 100 BLOWER MOTOR COOLING FAN SCHEMATIC 101 PICTORIAL DIAGRAM 102 EXPLODED VIEW PARTS LIST 103 ASSEMBLY LEVEL 1 104 ASSEMBLY DOOR 105 ASSEMBLY PANEL 106 INVERTER 107 ASSEMBLY LEVEL 2 108 DOOR HINGE ASSEMBLY RHS 109 DOOR HINGE ASSEMBLY LHS 110 ASSEMBLY LEVEL 3 111 ASSEMBLY MOTOR...

Page 5: ...v ASSEMBLY LEVEL 4 115 ...

Page 6: ...vi INDEX ...

Page 7: ...1 SAFETY INSTRUCTIONS ...

Page 8: ...electrical shock Warning lease refrain from heating liquids or other foods in a sealed container since the package may explode Do not use metal lids or aluminum foil while cooking in this oven Please refrain from spraying any water or liquid on power cord and do not submerge in water Do not operate the oven in the power cord or outlet is damaged oven has been dropped or physically damaged or oven ...

Page 9: ...d electrician for assistance WARNING To reduce the risk of electrical shock the unit must be properly grounded Power Cord Replacement If the power cord is damaged in any way is must be replaced by the manufacturer Pratica Inc an authorized service agent or qualified personnel Fire Risk Reduction Please remove all content from inside the oven before applying power e g utensils paper food particles ...

Page 10: ...of hinges and latches 5 evidence of dropping or abuse c Before turning on microwave power for any service test or inspection within the microwave generating compartments check the magnetron wave guide or transmission line and cavity for proper alignment integrity and connections d Any defective or misadjusted components in the interlock monitor door seal and microwave generation and transmission s...

Page 11: ...5 SPECIFICATIONS INSTALLATION ...

Page 12: ...6 SPECIFICATIONS INSTALLATIONS Spec Sheet ...

Page 13: ...pth footprint 21 4 544mm Depth 31 7 806mm Volume 0 74 cu ft 21 Liters Installation Instructions Please read the following instructions carefully Install this unit in accordance with the instructions below Unpacking Instructions 1 Remove the unit from the packaging 2 Check the packaging and oven cavity thoroughly for accessories and literature 3 Discard any packaging inside the cavity e g cardboard...

Page 14: ...n up by the door handle Doing so may cause the door to misalign or cause damage to door hinges which will not be covered by warranty WARNING Never lift the unit from the removable front panel under the door as it may get Damaged or may come loose while lifting WARNING This unit is not meant to be stacked Please contact Pratica Inc for further details WARNING This unit is not meant to be installed ...

Page 15: ...ith the safety interlocks b Do not place any object between the oven front face and the door or allow soil or cleaner residue to accumulate on sealing surfaces c Do not operate the oven if it damaged It is particularly important that the oven door close properly and that there is no damage to the 1 Door bent 2 hinges and latches broken or loosened 3 door seals and sealing surfaces d The oven shoul...

Page 16: ...10 DAILY CLEANING QUARTERLY MAINTENANCE ...

Page 17: ...11 DAILY CLEANING QUARTERLY MAINTENANCE ...

Page 18: ...allowed to cool down properly Turn unit off by pressing the power button on panel Open oven door slightly to allow heat to disperse quicker Allow the unit to cool for approximately 30 40 minutes prior to cleaning Step 2 Cleaning the Wire Rack The rack is held in place by 2 metal hooks that act as security tabs to prevent the rack from coming loose Pull up on back part of rack and then pull towards...

Page 19: ...her instructions Step 5 Cleaning Air Filter WARNING Filter must be installed during oven use Only remove to clean when oven is not in use The air filter is located under the removable front panel under the door Locate the tab on the filter and pull towards the front of the unit Rinse the filter in hot water to remove any buildup and allow the filter to dry prior to reinstalling Step 6 Removing Foo...

Page 20: ...towel to remove as much left over cleaner and debris as possible Step 9 Cleaning the Oven Door Spray the cleaner on a nylon scrub pad or cloth to clean oven door If buildup occurs you may spray the cleaner directly on the affected area Dry down using a dry cloth or towel Step 10 Apply Oven Guard Apply the oven guard to a dry cloth or towel Wipe all surfaces of the cavity avoiding the IR element Th...

Page 21: ...ust mask and a pipe cleaner Step 1 Cool Down Oven and Unplug Turn the oven off by pressing the power button on panel Please look at daily cleaning for further instructions on how to clean the cavity Once oven is cooled down carefully unplug the power cord from the outlet Step 2 Remove Air Filter Remove bottom panel under door Locate the tab on the filter and pull towards front of unit Clean or rep...

Page 22: ...ing Clean the housing cover and verify that the vent slots are not blocked WARNING Do not attempt to clean the catalyst or spray any cleaner directly on it Step 6 Cleaning the Exhaust Pipe Visually look into the exhaust pipe to make sure that it is clean with no blockage You may use a pipe cleaner to break up any buildup id necessary Make sure the exhaust pipe lines up with the vent housing for pr...

Page 23: ...e the rear panel completely to gain access to both cooling fans You may use a clean damp cloth to clean the cooling fan blades Reinstall the rear panel and verify the vent tube goes into the rear catalyst housing Step 9 Install Air Filter Reinstall air filter and make sure all Phillips screws are secure The oven is ready to be turned on Step 9 Step 8 ...

Page 24: ...18 THEORY OF OPERATION ...

Page 25: ...19 THEORY OF OPERATION ...

Page 26: ...chnology 1 The top heater transfers thermal energy to the circulation air created by the blower motor located in rear of unit 2 The blower motor spins at high revolutions causing high speed air to circulate trough the top cavity trough the top and bottom jetplate and back to the blower 3 The catalytic converter catches and burns off most of the grease and odors when the forced air passes through i...

Page 27: ...those that do not need a medium to spread they can spread through a vacuum or certain kind of materials A fewer examples of electromagnetic waves are sunlight radio waves microwaves x rays and many others The waves may be represented by a solenoid similar like the picture below The wave changes from positive to negative and returns to neutral performing a complete cycle The number of times this cy...

Page 28: ...a low frequency As we move down the spectrum the length of the waves become smaller and the frequency becomes higher ex X Rays and Gamma Ray We also observe that the microwaves fit among the TV transmission waves and the infrared levels The microwaves utilized for microwave ovens have approximately 12 cm of length with a frequency of 2 45GHz In other words they complete 2 450 000 000 cycles per se...

Page 29: ...ce in a depth that ranges from two to seven centimeters heating the molecules of water fat and sugar by making them vibrate The heat is transmitted to the interior of the food by thermal conduction demystifying the idea that the microwaves cook food from the inside out These are three characteristics of the microwaves which are important Microwaves are reflected by the metals and can NOT pass thro...

Page 30: ... each other so when a food is exposed to an electromagnetic field the molecules are all aligned so that their charges point at the same direction When the electromagnetic field inverts the polarity the molecules also have their directions inverted As the microwaves invert their polarity 2 billion and 450 million times per second the molecules will also vibrate at the same frequency hitting one ano...

Page 31: ... walls shelves and finally the food In both cases the heat begins to cook the outside of the food first then slowly begins to cook the middle or center When product is cooked in a microwave oven the microwaves will start to penetrate the food The penetration of the microwaves in the food depends on the density of the food For example bread will be penetrated easier the meat because of its density ...

Page 32: ...26 OVEN CONTROLS AND COOKING ...

Page 33: ...27 OVEN CONTROLS AND COOKING ...

Page 34: ...OOKING Control Panel 1 Digital panel 2 Play button 3 Up Down Arrow keys 4 Numerical keypad 5 Temperature control 6 USB function 7 Warning Heater 8 Return Key 9 Ok button 10 Manual cook mode 11 Cool down mode 12 On Off key 12 ...

Page 35: ...New menu settings can be uploaded using a USB drive or inputting manually Temperature Set Up Preheating 1 Select Cook Temperature by pressing the Temperature ad On Off keys at the same time 2 The following screen will appear and allow changes to be made to the top and bottom set point temperatures by pressing the Enter key 3 To turn the oven press the Play button as shown below ...

Page 36: ...y Heat Soak period of 5 minutes To change this time turn unit off and press the Cool Down and On Off keys at the same time Use the Up Down arrow keys to change from 0 15 minutes 6 The food categories will display when the warm up cycle is complete WARNING Oven cavity and inner door are HOT at this point ...

Page 37: ...wich category Note The Up or Down arrow keys can be pressed to view categories 5 8 2 The following message will appear while the cook cycle is processing 3 The oven will display Ready when cook cycle is complete The food is ready to be checked or removed at this point WARNING Food content and container be HOT please exercise caution when removing ...

Page 38: ...ditional cook time if desired ex 10s 20s 30s Note The oven only gives 10 seconds to make selection before going back to normal menu screen 5 Cool Down Press the On Off key and open door slightly to cool faster Note The cooling fans will remain on for appx 20 minutes after the unit has been shut down ...

Page 39: ...when setting the total cook time The following information is critical when creating a new recipe The initial temperature of the product will change the desired results if not considered e g frozen cold or room temperature The size and or weight variation of the portion of product will also play a big role in determining the correct settings Only use containers approved for a microwave oven to pre...

Page 40: ... turned off press and hold the Down arrow and On Off keys at the same time This will bring up the menu screen and Edit Mode can be accessed from this point 2 Option 2 allow the oven to warm up and bring up menu 3 Press Enter on either the category or sub menu screen and the entire screen will highlight The operator can select the numerical button associated with the category or menu they want to e...

Page 41: ... name of the selected Category Use the numerical keys to name the category 6 Creating Editing a menu Once a category is selected press the Enter key to highlight the menu screen Choose which menu you want to edit by pressing the numerical keys next to the item 7 Press the number 2 to begin editing or creating a menu Press the number 3 to delete the menu selected ...

Page 42: ... up to 6 steps in the cooking process 9 Each stage has 4 categories as shown below Starting from the top down the options are time chamber temperature RI resistance temperature and blower speed 10 Once the step is complete press the Return key to go back to Steps 1 6 page 11 Repeat the process if additional steps are needed ...

Page 43: ...lift the rubber tab of the USB terminal and insert the USB drive while the unit is on and the menu is displayed b Press c Using the alphanumeric keypad press option 2 or 3 Option 2 Export all recipes from the oven to a USB drive Option 3 Import recipes from a USB drive to the oven USB Black cover ...

Page 44: ...ING How to Load Firmware on Chef Express Step 1 Turn the oven off and disconnect the power plug from the wall Remove the side panels and top cover Step 2 Disconnect the USB cable from the display control board See illustration ...

Page 45: ... installing the ribbon cable See illustration Step 4 Connect the USB connector from the black box to a computer Wait approximately 2 minutes for the drivers to download Step 5 Apply power to the oven but do not press the ON key Unzip the file GRAVA_EXP Note A Zip or RAR file extractor is needed Blue side should be up Empty pin up ...

Page 46: ...40 OVEN CONTROLS AND COOKING Step 6 Open the folder and choose GRAVA_EXPRESS_G3_STD Step 7 Command prompt screen will open and start the loading process See illustration ...

Page 47: ...bbon cable from the display control board Reconnect the oven USB cable back to the display control board See illustration Step 10 Unplug the power cord from wall and wait 2 minutes before reconnecting Reconnect the power plug and wait for 5 seconds Press the power ON and the number 2 key at the same time to confirm the software version ...

Page 48: ...42 TEST MODE ...

Page 49: ...43 TEST MODE ...

Page 50: ...ER RI The temperature of the bottom IR element Information Screen To view the Information Screen press and hold the number 2 and the On Off keys at the same time from the oven off position VERSION The current firmware version of the unit COUNT FILTER The total hours of operation TEMP PANEL The temperature inside the electrical compartment that is registered by the Control Board COUNT REC The numbe...

Page 51: ...Measurement or Language press and hold the number 4 and On Off keys at the same time from the oven off position RANGE TEMP Allows to toggle between Fahrenheit and Celsius LANGUAGE The Chef Express has four available language selections which are English Portuguese French and Spanish ...

Page 52: ...ical error Inverter Critical Errors Right The digit on the right indicates the amount of critical errors registered after the inverter tries to reset but continues to have a problem Second Line Time Out Error Stop Frame Error Timeout Error Left A communication error that occurs when the Main Control Board sends a command signal to the inverter but does not receive the signal back Wrong Frame Error...

Page 53: ... To identify the exact error code the inverter itself must be checked Magnetron Test To perform a Magnetron Test press and hold the number 6 and On Off keys at the same time from the oven off position Press the Play key to start the Magnetron Test The microwaves will engage and the results will show on the screen If the test shows OK Approved the microwave circuit tested fine If the test shows Mag...

Page 54: ...stered a temperature of 149 degrees Fahrenheit TEMP BOARD MAX The amount of times the board has registered a temperature over 149 degrees Fahrenheit Keypad Test To perform a Keypad Test press and hold the number 0 and the On Off keys at the same time from the oven off position The keypad test will verify that each key is functioning when pressed by showing the key function on the screen ex Pressin...

Page 55: ...49 MICROWAVE SYSTEM ...

Page 56: ... the positive half cycle of the alternate current voltage and charges the capacitor In this half cycle the diode works as a short circuit allowing the entire current pass through it In the negative half cycle the voltage of the capacitor and the 2000 volts are added resulting in a 4000V system In this half cycle the diode works as bridge allowing the current to flow to the Magnetron that generates...

Page 57: ... does not allow for any adjustments to the sealing surfaces However the adjustments to the door and the sealing surface are made by loosening the 10 Phillips head screws around the perimeter After loosening the inner door choke assembly is free to move closer to the oven cavity as necessary Retighten screws to secure the adjustment Refer to page 68 for proper microwave leak testing procedures An R...

Page 58: ...microwave can be energized The Monitor switches is locked on the left side of the oven and is used to act as a fail safe if both the Primary and the Secondary switches were to fail This switch is wired in series with a separate relay Interlock Relay used to open a fuse and disable the circuit This dead short condition will occur if the Monitor switch opens before either the Primary or Secondary sw...

Page 59: ...ing the oven with the power connected Observe the LED s from a safe distance The Primary and Secondary switches are engaged with a single actuator attached to the right side hinge Because of this design the door position has a direct and precise relationship with the switch contacts The actuator is a round post with a step machined into one side to allow for the Primary switch to open before the S...

Page 60: ...op access the LED and the switches 3 Loosen the 2 Phillips screw on the mounting bracket and the two 1 Phillips screws holding the switch body 4 Place a 0 040 1 0mm gauging tool between the switch body and the metal paddle 5 Confirm the adjustment is correct and tighten mounting hardware 6 Open and close the door while checking the sequence of de LED lights on the control board SW1 first SW2 secon...

Page 61: ...n and remove both side and top panels 2 Disconnect the thermostat wires and measure the continuity between the terminals of the thermostat as show in the picture If continuity is present the thermostat is good If no continuity is present replace the thermostat 20 Amp Fuses The 20 amp fuses are utilized to protect each microwave circuit from over current Both fuses are located inside a fuse termina...

Page 62: ...is is the third method to prevent microwave energy from leaving the cavity during an open door condition Voltage Relay The voltage relay is responsible for applying the correct voltage to the microwave high voltage transformers The control board determines the voltage based on the current transformer and then sends the control voltage to the relay to switch between 208V and 240V accordingly Relay ...

Page 63: ...pen and measure the continuity between the COM1 terminal and the NO3 terminal of the SW1 SW2 and SW3 switches 4 If the door switch terminals have no continuity move on to the next test If the door switch read continuity the door switch is bad and needs to be replaced 5 Close the oven door and verify the continuity between the COM1 and NO3 terminals on all switches If the terminals have continuity ...

Page 64: ...mer Never attempt to isolate by removing the secondary wires due to high voltage Please follow the instructions below to obtain an amp draw on both microwave circuits 1 Remove both sides and top panels from the unit 2 Locate the brown CT wire looping through the current sensor on the main control board 3 While the oven is off press and hold the number 6 and On Off keys to enter the magnetron test ...

Page 65: ...ron by heating the cathode The magnetron will fully energize when the 2000V are applied from the secondary high voltage winding causing the emission of electrons that start to produce the microwave radiation The two longer wires of the transformer are the secondary low voltage wires 3 6V and the wire grounded to the transformer chassis belongs to the secondary high voltage side 2000V as seen in th...

Page 66: ...scharge manually by grounding each capacitor terminal 3 Unplug all the wires from the HV transformer terminals 4 With the ohmmeter measure the resistance across the filament wires as shown in the picture on the right 5 The measured resistance value should be 0 0 ohms or a very low reading If the ohm reading is open or very high replace the transformer Testing Secondary HV Winding 2000V 1 Remove th...

Page 67: ...ly before commencing repair To perform the capacitor test a multimeter will be necessary 1 Unplug the oven and wait 5 minutes for the high voltage capacitor to discharge or discharge manually by grounding each capacitor terminal 2 Remove the rear panel of the unit 3 Unplug all wires and manually discharge capacitor 4 With the multimeter adjusted to the highest resistance scale measure the ohms bet...

Page 68: ...est a multimeter and an extra 9V battery will be necessary 1 Remove the rear panel of the unit 2 Unplug the oven and discharge the capacitor manually by grounding each capacitor terminal 3 Disconnect the cables from the diode and manually discharge the capacitors 4 Connect the voltage meter in series with high voltage diode 5 Using a multimeter set to DC voltage connect one meter lead to one side ...

Page 69: ...en number of flaps pointing to the filament The antenna is connected to the anode flaps The filament cathode is located in the center of the Magnetron The cathode in the Magnetron is a filament that is supplied by the low voltage secondary 3 6 V of the transformer which emits electrons when heated These negatively charged electrons are attracted by the anode which is positively charged when the 4 ...

Page 70: ...ow As the electrons pass by the cavities the cavities begin to resonate and emit microwave radiation The microwave radiation that is produced by the cavities is captured by the antenna and funneled into the waveguide which will guide the microwave radiation into the cook cavity The microwave then gets attracted to the food product s due to the moisture MAGNET MAGNET ANTENNA ANODE FILAMENT CATHODE ...

Page 71: ...er set to lowest resistance scale measure the continuity between both magnetron terminals as shown in the picture below If the resistance measure zero ohms as shown in picture below move on to step 6 If the reading shows high resistance or open the magnetron is faulty and will need to be replaced 6 With the multimeter set to the highest resistance scale measure the continuity between each terminal...

Page 72: ...d to reduce any false readings Lees expensive meters with only an audible alarm are not recommended The meter needs to register readings of less than 1 0mW cm2 and greater than 5 0mW cm2 for proper documentation by the field technician The Chef Express oven utilizes a door choke design to efficiently seal the microwaves in the oven cavity The technician needs to inspect the door surfaces for debri...

Page 73: ...he cook cavity through the waveguides These waveguides are attached to the cook cavity sides with a special stainless steel gasket between the two surfaces This gasket is held in place by the compression of the mounting hardware High temperature silicone must not be used to seal the gasket to the waveguide because the gasket needs an electrical connection to the waveguide The silicone is transpare...

Page 74: ...ve ample time to move the probe around the entire perimeter of the door 5 Star the cook cycle and measure the microwave emission with the meter positioning it perpendicular to the surface that is being measured Make sure to move the meter at 1 0 in per second while doing the test 6 While performing the leakage test note any meter spike areas that come close to 5mW cm2 for later re measurement 7 Re...

Page 75: ...69 IMPINGEMENT SYSTEM ...

Page 76: ...rs before continuing repairs Please follow the instructions below to test the blower motor 1 Unplug the oven and discharge the capacitors for safety purposes 2 Remove the rear panel from the unit 3 Unplug all 3 wires from the blower motor labeled V W U 4 Check continuity across all 3 windings in different combinations Each combination should have around 5 6 ohms ex V to W V to U W to U If no conti...

Page 77: ...utilizes a data communication protocol called MODBUS to communicate with the main control board The picture below shows the connections of the frequency inverter Note The ground cable must be properly grounded to the oven chassis IMPORTANT The switches on the side of the Frequency Inverter should always be in the ON position ...

Page 78: ...will continue with regular functioning If the communication is not immediately restored the main control board will attempt to reset the inverter ten times before an error message on the screen as shown below Frequency inverter errors The main control board will keep a counting log of the failures that occur in the inverter To know this information follow the steps below 1 Inside the Option Screen...

Page 79: ...voltage and will not accept the enabling command 3 FAULT The inverter will flash the fault code on the screen when there is a problem 4 NOT USED Without indication 5 CONFIGURATION Indicates the inverter has an incompatible program for the parameter After pressing the key it will keep showing an arrow until the incorrect setting is corrected as shown in the figure When a failure occurs the frequenc...

Page 80: ... are per the supply source network and the P296 parameter Input voltage too low Missing input phase Failure in preload circuit F022 Overvoltage in CC bus Overvoltage failure in intermediate circuit Wrong supply voltage Supply voltage is very high Load inertia very high or very fast deceleration ramp Very high P151 adjustment F051 Overtemperature in IGBT s Power module sensor over temp Temperature ...

Page 81: ...er The high limit thermostat protects the oven against overheating When the oven temperature rises above 752 F 400 C the contacts open and shuts off power to the heaters The high limit will reset automatically and usually happens within 5 minutes Testing High Limit Thermostat 1 Unplug the oven 2 Remove the right side panel of the unit 3 Unplug the wires and test or continuity If continuity is pres...

Page 82: ...Look for any physical damage to the heater or wires If any damage is seen remember to unplug the unit before continuing 3 Locate the top heater contactor on right side of unit to get amp draw 4 Place amp clamp around bottom right heater wire and turn unit on The amp draw should be between 14 16 amps on the white wire If there is no amp draw verify the heater breaker is not tripped If the breakers ...

Page 83: ... 2 Look for any physical damage on the heater element or wires If any damage is seen remember to unplug the unit before continuing 3 Locate the bottom heater contactor on right side of unit to get amp draw 4 Place amp clamp around bottom right heater wire and turn unit on The amp draw should be between 14 15 amps on the bottom white heater wire If there is no amp draw verify the heater breaker is ...

Page 84: ...ok chamber sensor occurs the board will stop the operation of the oven and will display the following fault code on the screen If the IR temperature sensor has a problem the oven will continue to work however the red triangle indicator light will illuminate below the display To verify if the sensor has an issue turn unit off and press the number 1 and On Off keys simultaneously to enter the temper...

Page 85: ...rification screen Warning Make sure to unplug the unit before installing jumper wire Once the jumper wire is installed plug the unit back in and press the number 1 and On Off keys simultaneously to bring up the temperature verification screen If the sensor is reading the room temperature then the board is registering correctly and the sensor needs to be replaced If the board registers any other re...

Page 86: ...80 CONTROL SYSTEM ...

Page 87: ...81 CONTROL SYSTEM ...

Page 88: ...The display is attached to the control board and will come together if the control board is ordered The board has a current sensor which measures the amp draw of the microwave circuit through the brown CT wire looping through it The current sensor is what determines if the microwave circuit is working correctly by communicating the registered amp draw to the board ...

Page 89: ...observed replace the component or repair the wire if needed If a unit has no power always remember to check the power outlet to verify incoming 208 240 AC voltage and the power supply The control board is powered by the 12V DC given by the power supply If incoming AC voltage from the wall or outgoing DC from the power supply are not present further troubleshooting is required with the components I...

Page 90: ...his point you will be able to press each individual button and the display register the command 3 If the problem is only with a single button and it the display does not register the command when pressed the keypad will need to be replaced 4 If the problem is with all the buttons on the keypad Check the ribbon cable for any damage or loose connection at the control board If damage is present repla...

Page 91: ...ting the Speaker If the speaker is no longer audible check the speaker wires to make sure they are secure the terminals If wires are secure check the wires for DC voltage coming from the control board If DC voltage is present replace the speaker If the speaker sound is very faint the speaker will need to be replaced ...

Page 92: ...86 POWER COMPONENTS ...

Page 93: ...87 POWER COMPONENTS ...

Page 94: ...esting EMI Filter To test the EMI Filter test across both terminals for incoming and outgoing AC voltage to verify that the voltage is passing through correctly 1 Remove rear panel from unit 2 Measure voltage across both input terminals should be 208 or 240V 3 Measure voltage across both output terminals if the voltage is the same as input the EMI Filter is good If the voltage is different by a la...

Page 95: ...er reads correct line voltage move on to step 3 If the multimeter does not read line voltage verify the wires are secure the store breaker is not tripped and correct voltage is getting to the unit or oven fuse is not blown 3 Measure the DC voltage in the bottom two terminals labeled V and V as shown in the picture If the multimeter registers 12V DC then power supply is good If the multimeter regis...

Page 96: ...oses manually discharge capacitors before troubleshooting cooling fans due to proximity 1 Unplug the unit and remove the rear panel 2 Manually verify the cooling fan spins freely and not seized If cooling fan is seized not spinning replace the cooling fan 3 Disconnect the cooling fan cables from the connectors and check for continuity If the meter registers continuity then the cooling fan is fine ...

Page 97: ...ug the oven and remove the right side panel 2 With a flathead screwdriver locate the tab on the bottom and push down with the screwdriver At this point the fuse and holder will release allowing you access to open the side tab where the fuse is located 3 Remove the fuse and check for continuity If the fuse reads open replace the fuse ...

Page 98: ...92 FILTERING SYSTEM ...

Page 99: ...93 FILTERING SYSTEM ...

Page 100: ...other components The filter is located on the bottom of the unit and can be removed by pulling the filter and tray out towards the front of the oven The filter can be rinsed off with water and reinstalled allow filter to air dry before reinstalling in oven This filter does require regular maintenance and occasional replacement if damage The filter must be kept clean to ensure proper ventilation of...

Page 101: ... 246 C CAUNTION The catalyst can only be cleaned by approved non caustic oven cleaner provided by Pratica Inc and rinsed with distilled water The catalytic converter can become seriously damaged if cleaned with any other product Vent Catalyst In addition to the main catalytic converter the oven contains a secondary catalyst in the vent tube path This catalyst further assists in the breakdown of gr...

Page 102: ...96 CHEF EXPRESS SCHEMATICS ...

Page 103: ...97 CHEF EXPRESS SCHEMATICS ...

Page 104: ...98 CHEF EXPRESS SCHEMATICS Control Board Schematic ...

Page 105: ...99 Heater Schematic ...

Page 106: ...100 CHEF EXPRESS SCHEMATICS Microwave Circuit Schematic ...

Page 107: ...101 Blower Motor cooling Fan Schematic ...

Page 108: ...102 CHEF EXPRESS SCHEMATICS Pictorial Diagram PRATICA CHEF EXPRESS SPEED OVEN FIELD SERVICE WIRING DIAGRAM SERIAL 70133 ABOVE 208 240V SINGLE PHASE ...

Page 109: ...103 EXPLODED VIEW PARTS LIST ...

Page 110: ...104 EXPLODED VIEW PARTS LIST Assembly Level 1 ...

Page 111: ...105 Assembly Door ...

Page 112: ...106 EXPLODED VIEW PARTS LIST Assembly Panel ...

Page 113: ...107 Inverter ...

Page 114: ...108 EXPLODED VIEW PARTS LIST Assembly Level 2 ...

Page 115: ...109 Door Hinge Assembly RHS ...

Page 116: ...110 EXPLODED VIEW PARTS LIST Door Hinge Assembly LHS ...

Page 117: ...111 Assembly Level 3 ...

Page 118: ...112 EXPLODED VIEW PARTS LIST Assembly Motor ...

Page 119: ...113 Assembly Terminal Block Support ...

Page 120: ...114 EXPLODED VIEW PARTS LIST Assembly Power Components Support ...

Page 121: ...115 Assembly Level 4 ...

Page 122: ...n Square Boulevard Suite 200 2018 Pratica Products Inc USA Garland TX 75040 For service or information Pratica Products Inc USA 675 Town Square Boulevard Suite 200 Garland TX 75040 1 214 299 7726 info praticausa com www praticausa com ...

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