Version 3.0
Version 2.0
EC402s
US Models including WAWA
SERVICE& PARTS MANUAL
This manual covers US models manufactured from:
Version 2.0 Serial No. 000745 –001199
Version 3.0 Serial No. 001200 onwards
CAUTION MICROWAVE EMISSIONS
DO NOT BECOME EXPOSED TO EMISSIONS FROM THE MICROWAVE
GENERATOR OR PARTS CONDUCTING MICROWAVE ENERGY
402s Ovens Pt. No. 32Z3522 Issue 5
1
ISSUE 5
23.02.2008
SERVICE MANUAL
TABLE OF CONTENTS
Microwave safety precautions .................................................3
Safety code..............................................................................4
Product specifications..............................................................5
Installation instructions ............................................................6
Main features ......................................................................7– 9
Principal components: RHS ...................................................10
Principal components: LHS ...................................................11
Principal components: Top ....................................................12
Principal components: Back View..........................................13
Principal components: Power Supply ....................................14
Principal components: Cavity Parts.......................................15
Principal components: External Panels .................................16
Principal components: Control Panel.....................................17
Parts Matrix...................................................................... 18-19
Procedure for Microwave Emission test .......................... 20-21
Procedure for Power output measurement............................22
Procedures for Principal Component tests ..................... 23-24
Procedure for door interlock adjustment.......................... 25-26
Hot Air Motor and controller............................................. 27-28
Wiring Diagrams ....................................................................29
Trouble Shooting Guide................................................... 30-34
Appendix 1: Temperature Probe............................................35
Appendix 2: MenuKey Procedures .................................. 36-37
Appendix 3: Cleaning Procedure ..................................... 38-40
Appendix 4: Recommended Spares List ...............................41
Appendix 5: PCB connection Points ................................ 42-43
Appendix 6: Engineering Test Settings..................................44
Merrychef USA
1111 North Hadley RD
Fort Wayne
IN 46804
Phone: 877/404 - 6872 Fax: 800/285 - 9511
e-mail: info@merrychefusa.com
402s Ovens Pt. No. 32Z3522 Issue 5
2
MICROWAVE SAFETY PRECAUTIONS
CAUTION
WARNING TO SERVICE TECHNICIANS
PRECAUTIONS TO BE OBSERVED BEFORE AND DURING
SERVICING TO AVOID POSSIBLE EXPOSURE TO
EXCESSIVE MICROWAVE ENERGY
(a) Do not operate or allow the oven to be operated with the door open.
(b) Make the following safety checks on all ovens to be serviced before
activating the magnetron or other microwave source, and make repairs
as necessary:
1) interlock operation.
2) proper door closing.
3) seal and sealing surfaces (arcing, wear, and other damage).
4) damage to or loosening 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 systems shall be
repaired, replaced, or adjusted by procedures described in this manual
before the oven is released to the owner.
(i) For U.S.A.
(e)
A microwave leakage check to verify compliance with the Federal
Performance Standard should be performed on each oven prior to
release to the owner.
(e)
(ii) For CANADA.
A microwave leakage check to verify compliance with the Canadian
Regulation, HEALTH AND WELFARE, SOR/79 920 should be performed
on each oven prior to release to the owner.
402s Ovens Pt. No. 32Z3522 Issue 5
3
SAFETY CODE
This manual is designed to assist engineers who have been on a recognised product familiarisation
and training course run by Merrychef. It has been prepared to offer technical guidance for the 402s
range of Ovens.
Please remember that it is wiser not to attempt a service task if you are unsure of being able to
complete it competently, quickly, and above all safely.
To avoid injury to yourself, and to protect the appliance from possible damage, please follow this
Safety Code when servicing these ovens.
Before attempting to repair the oven, check it for microwave emission using a calibrated
emission detector.
Check that the oven is not emitting microwaves, even when supposedly not in operation.
Check that the oven is not operating continuously, whether the display indicates cooking or
not.
Always discharge the HT capacitors before working on the oven using a suitably insulated
10 MΩ Resistor.
When testing the oven with covers off run for short periods of time only or magnetrons will
overheat and the display will show Error condition.
Before removing any covers from the oven, do all of the following.
• Switch off the mains supply and remove the plug from the wall socket.
or
• If the oven is hard wired, ensure that the power is turned off at the isolator switch.
Note:
The On/Off switch on the oven is not adequate protection against electric
shock, as it does not isolate all of the internal wiring from the mains.
Upon completion of a service the oven, or before reconnecting the appliance to the electrical
supply for testing, check all of the following points:
• All internal electrical connections are correct (see wiring diagrams).
• All wiring insulation is correct and is not touching a sharp edge.
• All grounding connections are electrically and mechanically secure.
• All door safety interlocks are secure and mechanically sound.
• The door operation is smooth, and the arms run freely in the slots.
• The door activates all four of the door interlock switches and in the correct order
• The temperature sensor is correctly connected to the Power PCB.
Before finishing a service call, recheck the following points:
• All of the electronics are functioning correctly and all of the touch pads are working.
• Microwave emissions are below permissible limit of 4 mW/cm².
• The power output of the oven is checked in accordance with the procedure page.
• Oven has correct 2 inch ( 50mm ) air gap all round and 2 inches ( 50mm ) above.
Air flow should not be restricted.
402s Ovens Pt. No. 32Z3522 Issue 5
4
PRODUCT SPECIFICATIONS
Model Number: 402S VVV F P C R TT ZZ
Example 402S2086DK3GMUS
Model No. EC402s
208V, 60Hz, 2P + GND supply, MenuKey Revision 3, General Market, USA
Supply
Voltage
Freq.
Hz
Phase/Supply
Control
Type
Rev Type
VVV F P C R TT ZZ
Voltage (ac)
208 = 208V
220 = 220-230V
240 = 230-240V
5 =
50Hz
6 =
60Hz
Phase Arrangement
A =
L + N + E (30 Amp)
B =
L1 + L2 + N + E
C =
2 P + Gnd (20 Amps)
K =
Electronic
MenuKey
1
2
3
GM =
General
Market
D =
2 P + Gnd (30 Amps)
Power
Requirements
208Volts
240Volts
Power Output Microwave 100%
Convection
208V ac 60Hz 30Amp 2P & G
240V ac 60Hz 40Amp 2P & G
1500watts
3250watts
Country
/Region
US =
USA
External
Dimensions
Height
Width
Depth
Weight Nett
Construction Cavity
Casework
402s Ovens Pt. No. 32Z3522 Issue 5
23.0 inches
23.0 inches
27.5 inches
198lb.s ( 90kg )
304 Stainless Steel
5
INSTALLATION INSTRUCTIONS
Installation Instructions for Mealstream Combination Ovens
Power Supply Requirements
The Mealstream Series should be connected to a suitable electricity supply, which can cope
with the switching-on surge that occurs with certain types of catering equipment, including
microwaves. Because of this requirement, we strongly recommend that a separate, suitably
rated supply is installed for the oven.
The supply for the oven should be fitted with a Type "C" or Time Delay circuit breaker.
If the oven is hard-wired to the supply, a double-pole isolator switch with a contact gap of at
least 1/8 inch ( 3 mm ) should be fitted.
Grounding requirement
This appliance must be connected to a grounded, metallic, permanent wiring system, or an
equipment grounding conductor should be run with the circuit conductors and connected to the
equipment grounding terminal or lead on the appliance.
Positioning the Oven
In order to maintain adequate ventilation for air intake
and exhaust, and to allow access for cleaning filters,
you must allow a minimum of 2 inches ( 50 mm )
clearance at the sides and rear of the oven.
Air intake temperature should not exceed 110°F/45°C
excessive temperature will lead to reduced operating duty
cycle, or premature ageing of internal components.
Failure to comply with these conditions will invalidate the
warranty.
NEVER Install an oven above fryers,
grills, griddles or any other
major heat source.
ALWAYS Place containers in the cavity
carefully - impact damage
may chip the vitreous enamel
coating on the runners and
baffle plate.
Note:
The minimum recommended
clearance required for air flow
402s Ovens Pt. No. 32Z3522 Issue 5
6
MAIN FEATURES
a
c
k
On/Off SWITCH
a
This is used to turn the oven On or Off.
IT DOES NOT ISOLATE INTERNAL WIRING
FROM THE MAINS SUPPLY.
MenuKey
b
The MenuKey System automatically changes
all the cooking programs with an electronic key
and allows program names to be identified.
OVEN CAVITY
c
The oven cavity is mainly constructed from
stainless steel panels. It must be kept clean.
GREASE FILTER
d
The grease filter must be cleaned on a regular
basis, and kept free of debris.
RACK
e
The cooking rack should be removed daily and
cleaned
HOT AIR FAN
f
Situated behind the grease filter and circulates
the hot air through the cavity.
RATING PLATE
g
The rating plate is situated on the rear of the
oven, and states the Model, Serial Number,
Electrical Ratings and Manufacturers
telephone number.
m
b
L
d
f
e
L
DOOR
h
The door consists of a thermally insulated inner
section, and an additional air gap provided by a
twin skinned door front to lower the surface
temperature.
DOOR SEAL
i
These ensure a tight seal around the door.
They should be kept clean and checked
regularly for signs of damage. Replace if worn
or damaged.
ELECTRICAL SUPPLY CORD
j
Electrical supply cord is situated on the rear of
the oven,
AIR FILTERS
k
Main intake for cooling air for internal
components. Must be clear of obstructions.
IMPINGER PLATES ( Upper & Lower)
L
Direct the air in the cavity. They must be
cleaned on a regular basis, and kept free of
debris
STEAM VENT PIPE
m
j
i
h
k
Vents steam from the oven cavity
g
402s Ovens Pt. No. 32Z3522 Issue 5
7
MAIN FEATURES
Electronic control panel: Version 2.0
PREHEAT/ COOL DOWN
PROGRAM
CANCEL PAD
Cancels all timed cooking cycles, pre-programmed
operations and stops the microwave energy. It does
not alter the oven temperature. If the oven is hot,
food will continue to cook and should be removed
from the oven immediately. This pad will also cancel
any incorrect operations. It will not erase programs.
FAN SPEED PADS
The Fan speed can be increased and decreased in
5% steps ( 10% to 100% )
FUNCTION PADS
Move through control functions in the Main Display
MAIN DISPLAY PANEL
Shows the principal functions of the oven.
When cooking, the time remaining counts down.
Also displays error messages and oven temperature.
(See TROUBLESHOOTING )
When storing and recalling a program the display
indicates the program number and details
TIME/ PROGRAM PADS
FAN SPEED PADS
MAIN DISPLAY
PANEL
POWER PADS
MenuKey
The MenuKey System automatically changes all the
cooking programs with an electronic key and allows
program names to be identified.
POWER PADS
The microwave power can be increased or
decreased adjusted in 10% steps. ( 0% to 100% )
The default setting is 50% microwave power.
PREHEAT/ COOL DOWN
Commences main oven heating cycle to a preset
temperature. Press and hold for 5 seconds to
commence cool down procedure ( See CLEANING )
PROGRAM
Activates program mode for storing programs in
memory START PAD Commences a program
TIME/ PROGRAM PADS
These pads are used for setting the cooking time in
1 second steps to a maximum of 10 minutes.
They are also used for storing and recalling
programs from 0-499
FUNCTION
PADS
START
CANCEL
PAD
MenuKey
Display Panel error messages
Message Condition Possible cause
ERROR MAGNETRON 1
ERROR MAGNETRON 2
ERROR MAGNETRON 1 & 2
CAVITY SENSOR ERROR
Magnetron 1 has overheated
Magnetron 2 has overheated
Magnetron 1 and 2 have
overheated
Cavity temperature exceeds
more than 90°F above
PREHEAT temperature
setting during cook cycle
402s Ovens Pt. No. 32Z3522 Issue 5
8
Blocked Air filter(s)
Oven located near hot air sources
Oven being used empty
Cooling fan failure
Magnetron failure
Indicates combustion ( fire ) in
oven cavity
Note: In service operations when
PREHEAT is set to 0°F this
message can appear when the
oven is operated
MAIN FEATURES
Electronic control panel: Version 3.0
COOL DOWN
FUNCTION
PADS
MenuKey 2
The MenuKey System automatically changes all the
cooking programs with an electronic key and allows
program names to be identified
CANCEL PAD
Cancels all timed cooking cycles, pre-programmed
operations and stops the microwave energy. It does
not alter the oven temperature. If the oven is hot, food
will continue to cook and should be removed from the
oven immediately. This pad will also cancel any
incorrect operations. It will not erase programs.
FUNCTION
PADS
MAIN DISPLAY
PANEL
FUNCTION
DISPLAY PANEL
Shows the principal functions of the oven.
When cooking, the time remaining counts down.
Also displays error messages and oven
temperature. When storing and recalling a
program the display indicates the program
number and details.
FUNCTION PADS
The function pads select options shown in the
DISPLAY PANEL.
COOL DOWN PAD
Puts the oven into Cool Down Mode prior to
cleaning
PADS
CANCEL
PAD
MenuKey
Error Message Condition Possible Cause
Magnetron 1 Overheat
Ensure air filters are clean
Allow oven to cool
Magnetron 2 Overheat
Ensure air filters are clean
Magnetron 1 has overheated
Magnetron 2 has overheated
Blocked air filters
Oven located near hot air source
Oven being used empty
Cooling fan failure
Magnetron failure
Allow oven to cool
Magnetron 1 & 2 Overheat
Ensure air filters are clean
Magnetron 1 & 2 have
overheated
Allow oven to cool
Ambient Overheat
Ensure air filters are clean
Allow oven to cool
Temperature inside casing
has exceeded limit
Blocked air filters
Restricted airflow to air filters
Oven located near hot air source
Circulation fan failure
Combustion (fire) in cavity
Cavity Overheat
Please contact service
Cavity temperature has
exceeded more than 565°F
Blocked air filters
Restricted airflow to air filters
Combustion (fire) in cavity
Heater Failure Cavity has not reached a
temperature of 100°F in 10
minutes
One or more heater elements
have failed and need to be
replaced
402s Ovens Pt. No. 32Z3522 Issue 5
9
PRINCIPAL COMPONENTS: Right Side
5
6
6
7
8
4
1
2
3
26A
26
No. Description Part No.
1 Cavity High limit Stat 30Z1024
2 Motor Start Capacitor 2µF ( Blue ) 30Z1298
3 Filter 16A 30Z1339
4 Air filter SA276
5 Stirrer motor Assembly SA238
5A Stirrer (inside cavity) SA213
6 Microswitch SW1
Microswitch SW2
7 Door Hinge Assembly RH SA202
8 Magnetron Cooling Fan 30Z1295
26 HV Capacitor 2500V 0.88μF ( 60HZ models ) 30Z1251
26A HV Capacitor clip (0.88μF) 88mm 31Z0521
30Z1294
402s Ovens Pt. No. 32Z3522 Issue 5
10
PRINCIPAL COMPONENTS: Left Side
3
5
5A
6
6
9
25A
25
No. Description Part No.
3 Filter 16A 30Z1339
4 Air filter SA302
5 Stirrer motor Assembly SA238
5A Stirrer (inside cavity) SA213
6 Microswitch SW3
Microswitch SW4
9 Door Hinge Assembly LH SA203
10 Motor Controller 30Z1293
25 HV Capacitor 2500V 0.88μF ( 60Hz models ) 30Z1251
30Z1294
10
4
25A HV Capacitor clip (0.88μF) 88mm 31Z0521
402s Ovens Pt. No. 32Z3522 Issue 5
11
PRINCIPAL COMPONENTS: Control Box
See
Principal
components:
POWER
SUPPLY
11
11
16
17
18
12
13
14
15
59
No. Description Part No.
11 Fuse 10A HRC 30Z0217
12 Gold resistor ( 220R ) 30Z0235
13 Relay PCB Assembly 11K0004
14 Ribbon Cable 15way 11Z0298
15 Ribbon Cable 10way MenuKey 11M0117
16 Logic PCB Assembly Version 2.0 SA231
16 Logic PCB Assembly Version 3.0 SA260
17 Transformer LT (Low voltage) 30Z1155
18 Fuse 1A 30Z0957
59 Sounder SA257
402s Ovens Pt. No. 32Z3522 Issue 5
12
PRINCIPAL COMPONENTS: Back view
19
20
22
21
28
27
No. Description Part No.
19
20
Cable Gland 31Z0500
Cable Gland Nut 31Z0499
Heater Element 208V 650W
DV0576
21
23
24
20
28
27
22
20
20
21 Magnetron 30Z1171
22 Magnetron Thermistor Assembly SA234
23 Convection ( Hot Air ) Motor Assembly SA208
24 Thermistor Cavity 30Z1315
27 Transformer 208/220/240V 60Hz 30Z1230
28 HT Rectifier 11H0010
Heater Element 220V 650W
Heater Element 240V 650W
402s Ovens Pt. No. 32Z3522 Issue 5
DV0606
DV0607
13
PRINCIPAL COMPONENTS: Power Supply
3
31
19
29
32
11
34
30
No. Description Part No.
3 Filter 16A 30Z1339
11 Fuse 10A HRC 30Z0217
19 Cable Gland 31Z0500
19 Cable Gland Nut 31Z0499
29 Electrical Supply Lead Assembly SA217
30 Terminal Block 31Z0447
31 Fuse 20A FLM 30Z1177
32 Fuse Holder 30A 30Z1178
34 Fuse Holder 10A 30Z0231
402s Ovens Pt. No. 32Z3522 Issue 5
14
PRINCIPAL COMPONENTS
Cavity parts
35
36
36
38
39
40
No. Description Part No.
35* Grease Filter ( 2 parts ) SA340
SA339
36 Stirrer Glass DV0492
37* Rack Support ( Not shown ) DV0114
38 Upper Impinger plate SA211
39 Rack DV0275
40 Lower Impinger plate SA266
* Parts 35 & 37 Contact Service Department
KFC Accessories
60
61
No. Description Part No.
60 Cool-down pan 32Z4028
61 Oven tray MC3175
62 Handle SA267
63 Griddle DV0221
64 Griddle carrier SA350
65 Chicken Griddle (SA350 + DV0221 + DV0267) SA133
62
63
64
65 Chicken Griddle SA133
402s Ovens Pt. No. 32Z3522 Issue 5
15
PRINCIPAL COMPONENTS
External Parts
45
41
42
43
4
Door Assembly
52
Control Panel
See page 15
52
51
50
4
49
48
47
46
No. Description Part No.
4
41*
42*
43*
45
46
47*
48*
49
50*
51*
52*
Air Filter SA276
Top Trim DV0187
Rear Panel SA329
Side Panel LH DV0091
Door Skin DV0501
Door Handle 32Z1066
Door Inner SA331
Door Choke DV0168
Door Seal DV0305
Bottom Trim DV0037
Side Panel RH DV0092
Door Assembly SA111
*Note:
On Ovens with Serial No.s before 000745 ( WAWA Models )
External Panels Items 41,42, 43, 45, 47,48, 50, 51, 52 are only available to special order.
402s Ovens Pt. No. 32Z3522 Issue 5
16
PRINCIPAL COMPONENTS
Electronic Control Panel Assembly
Version 2.0
55
Version 3.0
53
53
66
58
54
56
57
54
*Note:
On Ovens with Serial No.s
before 000745
( WAWA Models)
External Panels Item 51 is
only available to special order.
No. Description Part No.
53 MenuKey Dust Cover DV0052
54 Power switch (On/Off) 30Z1318
55 GM Membrane Version 2.0 DV0055
55 Membrane WAWA version DV0192
56* Front Panel Version 2.0 DV0036
57 Display Assembly & Header Version 2.0 30Z1299
58 MenuKey Socket 11K0005
66 GM Membrane Version 3.0 DV0254
67 Front Panel Version 3.0 DV0249
68 Display Assembly & Header Version 3.0 30Z1324
67
68
58
402s Ovens Pt. No. 32Z3522 Issue 5
17
Part number identification chart 1
Ref. No. Description Part No.
1 Cavity High limit Stat 30Z1024
2 Motor Start Capacitor 2µF ( Blue ) 30Z1298
3 Filter 16A 30Z1339
4 Air filter SA276
5 Stirrer motor Assembly SA238
5A Stirrer (inside cavity) SA213
6 Microswitch SW1, SW2, SW3, SW4 30Z1294
7 Door Hinge Assembly RH SA202
8 Magnetron Cooling Fan 30Z1295
9 Door Hinge Assembly LH SA203
10 Motor Controller 30Z1293
11 Fuse 10A HRC 30Z0217
12 Gold resistor ( 220R ) 30Z0235
13 Relay PCB Assembly 11K0004
14 Ribbon Cable 15way 11Z0298
15 Ribbon Cable 10way MenuKey 11M0117
16 Logic PCB Assembly Version 2.0 SA231
16 Logic PCB Assembly Version 3.0 SA260
17 Transformer LT (Low voltage) 30Z1155
18 Fuse 1A 30Z0957
19 Cable Gland 31Z0500
Cable Gland Nut 31Z0499
20
21 Magnetron
22 Magnetron Thermistor Assembly
23 Convection ( Hot Air ) Motor Assembly
24 Thermistor Cavity
25
25A HV Capacitor clip (0.88μF) 88mm
27
28 HT Rectifier
29 Electrical Supply Lead Assembly
30 Terminal Block
31 Fuse 20A FLM
Heater Element 208V 650W
Heater Element 220V 650W
Heater Element 240V 650W
HV Capacitor 2500V 0.88μF ( 60Hz Models )
Transformer 208/220/240V 60Hz
DV0576
DV0606
DV0607
30Z1171
30Z1315
30Z1251
31Z0521
30Z1230
11H0010
31Z0447
30Z1177
SA234
SA208
SA217
402s Ovens Pt. No. 32Z3522 Issue 5
18
Part number identification chart 2
Ref. No. Description Part No.
32 Fuse Holder 30A 30Z1178
34 Fuse Holder 10A 30Z0231
35* Grease Filter ( 2 parts ) SA339
36 Stirrer Glass DV0492
37 Rack Support DV0114
38 Upper Impinger plate SA211
39 Rack DV0275
40 Lower Impinger plate SA266
41* Top Trim DV0187
42* Rear Panel SA329
43* Side Panel LH DV0091
45* Door Skin DV0501
46 Door Handle 32Z1066
47* Door Inner SA331
48* Door Choke DV0168
49 Door Seal DV0305
50* Bottom Trim DV0037
51* Side Panel RH DV0092
52* Door Assembly SA111
53 MenuKey Dust Cover DV0052
54 Power switch (On/Off) 30Z1318
55 Membrane WAWA version DV0192
55 Membrane GM Version Version 2.0 DV0055
56 Front Panel Version Version 2.0 DV0036
57 Display Assembly & Header Version 2.0 30Z1299
58 MenuKey Socket
59 Sounder
60 Cool-down pan
61 Oven tray
62 Handle
63 Griddle
64 Griddle carrier
65 Chicken Griddle
66 GM Membrane Version 3.0
67 Front Panel Version 3.0
68 Display Assembly & Header Version 3.0
— Door seal sealant ( tube )
— Stirrer cover sealant ( tube )
— Grease Filter Cartridge
— Microswitch interlock spring
(SA350+DV0221+ DV0267)
402s Ovens Pt. No. 32Z3522 Issue 5
SA340
11K0005
SA257
32Z4028
MC3175
SA267
DV0221
SA350
SA133
DV0254
DV0249
30Z1324
31Z0186
31Z0527
SA340
31Z1247
*Note:
On Ovens with
Serial No.s before 000745
( WAWA Models )
Grease Filter 35, Rack 39
External Panel Parts
41,42, 43, 45, 47, 48,
50, 51, 52
are only available
to special order.
19
PROCEDURE FOR MICROWAVE EMISSION TEST (1)
Warning
Check for radiation emission after servicing. Should the emission be more than 4mW/cm² Inform
Merrychef service centre immediately. After repairing or replacing any radiation safety device,
keep a written record for future reference, as required by D.H.H.S. and Health and Welfare
Canada regulation.
This requirement must be strictly observed. In addition, the emission reading must be recorded
on the service repair documentation while in the customer’s premises.
Please Note
DO NOT attempt to carry out the
following procedure unless you have
the following tools.
Changing the Oven Profile
In order to carry out the test the oven PREHEAT
must be set to OFF[ V3.0 ] or 0ºF[ V2.0 ] to switch
off the convection heaters and the Manual
controls must be set to ON [ V3.0 ] or PROGRAM/
Tools required for microwave leakage test
MANUAL[ V2.0 ].
When the test is completed the oven must be
1.0 Pint ( 600ml) glass beaker
Supply of cold water
returned to its original settings or the appropriate
MenuKey can be used to reset the oven
automatically.
Microwave leakage meter
See Appendix 6 for changing the Oven Profile
Read and understand all of these notes and procedure before carrying out this operation.
Note before measuring.
• Make sure that the survey meter you are using has been calibrated and is suitable for
measuring frequencies of 2,450 MHz.
• Do not exceed meter full scale deflection, leakage meter should initially be set to the highest
scale, then adjusted down as necessary to ensure that low readings are measured on the most
sensitive range.
• To prevent false readings, hold the probe on the grip provided and move along the areas
indicated on the following page.
The probe should be moved at 1 inch/second (2.5cm/second)).
• With any casework removed the leakage should not exceed 4mW/cm².
• When measuring the leakage, always hold the probe at 2inches (50mm) from the test area
using the probe supplied with the instrument.
• Always hold the probe at right angles to the oven and point of measurement
Procedure:
1. Place 0.5 pint (275ml) of cold water in the 1.0 Pint ( 600ml ) glass
beaker.
2. Place the 1.0 Pint ( 600ml ) glass beaker in the centre of oven.
3. Set the leakage meter to the appropriate scale/range.
4. Set a time of 30 seconds with Fan speed at 10% and Power at 100%.
5. Press Start and move the survey meter probe along the areas
indicated on page 21. Open the door at 30 seconds and taking care
change the water. If the water boils the meter readings will be
inaccurate.
On completing the test remember to return the Oven Profile and
PREHEAT temperature to the original settings.
402s Ovens Pt. No. 32Z3522 Issue 5
20
Manual Mode
If the manual mode
screen does not
appear it must be
changed in the
OVEN PROFILE see
Appendix 6
PROCEDURE FOR MICROWAVE EMISSION TEST (2)
• Readings must be below 4mW/cm². If a level greater that 4mW/cm² is observed,
this should be reported to Merrychef Service Division immediately.
• In any case, notes should be kept of the leakage that is observed. In terms of level and
position on the oven. This should be kept with the service documentation.
Test for microwave leakage at all points marked with a
Control Panel
Door Perimeter
Door Perimeter
Rear Cover/ vents
402s Ovens Pt. No. 32Z3522 Issue 5
21
PROCEDURE FOR POWER OUTPUT MEASUREMENT
The power output specification 1500W on this model is established under IEC 705 standard
method. This method is only workable in Laboratory controlled conditions.
An approximate method is as follows:
Ensure the oven is cold before commencing the test
Changing the Oven Profile
In order to carry out the test the oven PREHEAT
must be set to OFF[ V3.0 ] or 0ºF[ V2.0 ] to switch
off the convection heaters and the Manual
controls must be set to ON [ V3.0 ] or PROGRAM/
MANUAL[ V2.0 ]
When the test is completed the oven must be
returned to its original settings or the appropriate
MenuKey can be used to reset the oven
automatically.
See Appendix 6 for changing the Oven Profile
Test procedure:
1. Fill one beaker ( glass or plastic ) with 2.11 pints ( one litre ) of tap water
at about 68ºF ( 20ºC ) and measure the water temperature.
( Use a thermometer with a
2. Place the beaker in the centre of the cold cavity.
3. Version 2.0 Press the Manual Function Pad to enter Manual Mode
Version 3.0 Press the lower RH function pad below the display to enter
Manual Mode
Set Time to 1 minute 3 seconds, Power to 100% and Fan to 0%.
Press the Start pad and wait until the counter reaches zero.
4. Take the beaker out immediately stir the water with a plastic implement
and measure the water temperature.
Calculate the temperature rise of water in the beaker.
The temperature rise of the water should be within the following range:
Temperature Rise
27ºF ( 15ºC ) Minimum
36ºF ( 20ºC ) Maximum
Note:
Power Output is affected by the line voltage under load.
For correct Power Output measurement the line voltage under load must be correct.
1
/10, 0.1 degree gauge ).
Manual Mode
If the manual mode
screen does not
appear it must be
changed in the
OVEN PROFILE see
Appendix 6
402s Ovens Pt. No. 32Z3522 Issue 5
22
PROCEDURES FOR PRINCIPAL COMPONENTS TEST (1)
1. Power Transformer Test
You will need:
A Digital Multi-meter (D.M.M.)
A Megger or similar resistance meter using 500V d.c.
WARNING: High voltages and large currents are present at the High Voltage Capacitor. It is very
dangerous to work near this part when the oven is on. NEVER make any voltage
WARNING: Even when the oven is not cooking, the High Voltage Capacitor has High Voltages
1 Isolate the oven from the mains supply.
2 Ensure that the High Voltage Capacitor is discharged before commencing work.
3 Remove all connections from the Power Transformer.
4 Using a D.M.M., check the resistance of the windings. Results should be as follows:
measurements at the High Voltage circuits, including the magnetron filament.
present because of the Soft Start circuit. Isolate the oven before testing.
See Safety Code ( Page 4 )
a Mains winding between tags
b High Voltage winding
c Filament winding
between terminals
5 Using a Megger, test the insulation resistance between:
Primary winding and chassis
Filament winding and chassis
One end of the High Voltage winding is connected to the
chassis, so this is not tested.
2. High Voltage Capacitor Test
You will need:
A Digital Multi-meter (D.M.M.)
A Megger or similar resistance meter using 500V d.c.
WARNING: High voltages and large currents are present at the High Voltage Capacitor. It is very
dangerous to work near this part when the oven is on. NEVER make any voltage
WARNING: Even when the oven is not cooking, the High Voltage Capacitor has High Voltages
measurements at the High Voltage circuits, including the magnetron filament.
present because of the Soft Start circuit. Isolate the oven before testing.
Approx. 1.1 Ω
Approx. 60 Ω
Less than 1 Ω
Pass if over 10 MΩ
Pass if over 10 MΩ
a
c
b
See Safety Code ( Page 4 )
1. Isolate the oven from the mains supply.
2. Ensure that the High Voltage Capacitor is discharged before
commencing work.
3. Remove all connections from the High Voltage Capacitor.
4. Using a D.M.M., check for continuity between the terminals &
compare results with table on next page.
402s Ovens Pt. No. 32Z3522 Issue 5
23
PROCEDURES FOR PRINCIPAL COMPONENTS TEST (2)
( High Voltage Capacitor Test continued, ensure steps 1-4 on previous page have been completed)
Between Terminals
Between Terminals and Case Pass if open circuit
5. Using a Megger, test the insulation resistance between the
terminals and the case.
Between Terminals and Case
3. High Voltage Rectifier Test
You will need:
A Megger or similar resistance meter using 500V d.c.
WARNING: High voltages and large currents are present at the High Voltage Capacitor. It is very
dangerous to work near this part when the oven is on. NEVER make any voltage
WARNING: Even when the oven is not cooking, the High Voltage Capacitor has High Voltages
measurements at the High Voltage circuits, including the magnetron filament.
present because of the Soft Start circuit. Isolate the oven before testing.
Pass if approximately 10 MΩ
Pass if over 100 MΩ
See Safety Code ( Page 4 )
1. Isolate the oven from the mains supply.
2. Ensure that the High Voltage Capacitor is
discharged before commencing work.
3. Remove all connections from the High Voltage
Rectifier.
4. Using the Megger, test for continuity in both
directions. Compare results with the table.
Open Circuit both ways
Conducts one way only
Short Circuit both ways
Conducts one way, leaks the other
FAIL
PASS
FAIL
FAIL
4. Magnetron Test
You will need:
A Megger or similar resistance meter using 500V d.c.
A Magnetron can be tested for an open filament or a short circuit
by carrying out a continuity check.
WARNING: High voltages and large currents are present at the High Voltage Capacitor. It is very
dangerous to work near this part when the oven is on. NEVER make any voltage
WARNING: Even when the oven is not cooking, the High Voltage Capacitor has High Voltages
measurements at the High Voltage circuits, including the magnetron filament.
present because of the Soft Start circuit. Isolate the oven before testing.
See Safety Code ( Page 4 )
1. Isolate the oven from the mains supply.
2. Ensure that the High Voltage Capacitor is discharged before
commencing work.
3. Remove all connections from the Magnetron.
4. A continuity check across the Filament terminals should be 1ohm or
less
5. A continuity check between each filament terminal and the
metal outer should read open.
402s Ovens Pt. No. 32Z3522 Issue 5
24
PROCEDURE FOR DOOR INTERLOCK ADJUSTMENT AND TEST 1
The door on the 402s oven is monitored by four microswitches. Three are used in the conventional
“Primary, Secondary and Monitor” switch arrangement shown below and the fourth sends a signal
to the Logic PCB. The switches operate as follows:
Door Interlock Arrangement: Switches shown in Door Closed position
RHS
L1
Power In
L2
1. Monitor switch
The Monitor switch will produce a short circuit across the mains supply when the door
is opened if the Primary interlock switch is faulty, thus blowing the microwave fuse
and rendering the oven inoperative.
2. Primary Interlock and Secondary Interlock
The Primary switch will cut off the microwave emissions from the oven when the door
is opened by breaking the electrical supply circuit to the transformers. The Secondary
interlock switch will cut off the microwave emission if the Primary switch has failed.
Note:
If operation of the Monitor switch has caused the Microwave Fuse to blow, the
Primary and Monitor microswitches must be changed as they may have been
damaged by the high short-circuit currents involved.
Primary
switch
Secondary
switch
Monitor
switch
Logic
PCB
LHS
Power
Out
Right Side
Monitor
SW1
Left Side
Door closed
Logic PCB
SW4
Microswitches
RH side
Primary
SW2
Secondary
SW3
402s Ovens Pt. No. 32Z3522 Issue 5
25
PROCEDURE FOR DOOR INTERLOCK ADJUSTMENT AND TEST 2
It is vital that the microswitches are adjusted to the correct position. There are two sets
switch assemblies located either side of the oven.
The interlocks ensure that the oven will not operate microwave with the door open.
WARNING
Before adjusting the microswitch
assemblies ensure that the oven
has been isolated from the
electrical supply.
Please note the terminals on the
microswitches remain live when
the oven is switched off, so
complete isolation is essential.
Objective
With a 1mm spacer located as shown, both
switches on both sides should be activated/ closed
position.
With a 5mm spacer located as shown SW2 and
SW3 should be open.
Method of adjustment.
By loosening the four screws on each mounting
bracket the microswitch assembly can be raised or
lowered and thereby the switches can be made to
operate at different door positions.
Procedure.
1. Isolate the oven from the Electrical supply.
2. Place a 1mm spacer between the cavity face
and the door seal as shown.
3. Working on the right hand side, adjust the
bracket so the SW2 ‘just’ operates.
4. Working on the left hand side, adjust the
bracket so that SW3 ‘just’ operates.
5. Remove the 1mm spacer and then place a
5mm spacer in the same position.
Check that SW2 and SW3 are open circuit and
not operated.
6. Repeat the steps above to ensure the setup is
correct.
7. Ensure that all the screws are tightened.
8. Reconnect the electrical supply.
Spacer
Door seal
Door
402s Ovens Pt. No. 32Z3522 Issue 5
26
PRINCIPAL COMPONENTS: Hot Air Motor & Controller 1
Convection and Fan Speed Control
The convection heat is provided by 5 elements located in the hot box at the rear of the oven
cavity. The hot air from the hot box passes over catalytic converters and is circulated into the
bottom and top of the cavity through the impinger plates. It returns through the removable grease
filter at the back of the cavity and into the fan.
Convection motor
The convection motor Is a 3-phase AC motor having a maximum speed of 7200 rpm controlled by
a motor speed controller.
The windings are thermally protected and in the event of a thermal fault a trip will operate and
shut down the motor speed controller.
Step
1
2
3
4
5
6
Motor/ controller fault finding
208V/240V, 60Hz Electrical supply into motor controller
Three phase connections to motor
Speed Controller connections to logic board
Motor thermal cut-out (short circuit)
Motor rotates freely/ not seized
Motor winding resistances:
Blue-Black 3 Ohms—4 Ohms
Black-Brown 3 Ohms—4 Ohms
Brown-Blue 3 Ohms—4 Ohms
Black or Brown or Blue to Earth (Open circuit)
402s Ovens Pt. No. 32Z3522 Issue 5
27
8x 31Z4016
M5 Flange nut
PRINCIPAL COMPONENTS: Hot Air Motor & Controller 2
Motor Controller
Provides an AC, 3-phase switched mode drive to
the convection motor and is controlled by a 0 - 10
Volt signal from the logic board. This allows the
motor to be adjusted from approximately 1500
rpm to 7000 rpm in steps of 5%.
Door Open = 1500 RPM
Door Closed (not cooking) = 3500 RPM
Door Closed (cooking) = as specified by
program or setting
Motor Speed and Logic board voltage table
Fan
speed %
100% 10V 7000 Full
50% 5V 3000 Door
20% 2V 1500 Door
Voltage
dc
Grey wire
to Motor
RPM Condition
Speed
Closed
Open
Wire
27
Blue 0V
Yellow 0-10V
Red +10V
Power Terminals
Wire 26
Motor Terminals
Blue Black Brown
V
Displays and messages: LED status display
LED Meaning Position
LED Off Inverter Off / No supply
1000 ms On/1000 ms Off Power On / Ready
LED On steadily Inverter Running
500 ms On / 200 ms Off General Warning
100 ms On / 100 ms Off Fault Condition
402s Ovens Pt. No. 32Z3522 Issue 5
28
LED
402s Ovens Pt. No. 32Z3522 Issue 5
CIRCUIT DIAGRAM: Issue 11
29
Trouble-Shooting Guide
Is the problem Food Quality or Fundamental
Operational Issue?
Food Quality
Standard Food Quality Checks
• Check that the PREHEAT temperature is
set correctly.
See User Manual.
• Check that the food being cooked has
been stored at the correct temperature.
• Check that the correct program is being
used.
Still Have a problem:
Select a Category.
• Cold Food Page 32
• Core TemperaturesLow Page 32
Fundamental
Standard Electrical Checks
• Check that oven is connected to an
Electricl Power supply and that any trip
that supplies the unit is not switched off.
• Check that the oven is switched on.
• Check the Electricl Power supply voltage
at the input terminal block.
• Check that all fuses are intact.
• Check that the overheat stat has not
tripped this can be checked by measuring
the voltage across the Auxiliary
transformer.
Still Have a problem:
Select a Category.
• No Display Page 31
• Cavity Sensor Error Page 33
• Magnetron / Over heat errors Page 34
Note : The following Diagnosis procedures may not expose all possible errors but have
been included for general guidance.
402s Ovens Pt. No. 32Z3522 Issue 5
30
OFF
OFF
Is Relay PCB
Active see D27
No Display
Is Logic PCB
Active ?
See D7 LED
display is in place and no obvious
ON
wires are disconnected or shorted.
ON
Check cable from logic PCB to
Still Have a problem?
Check 15 Way Ribbon
Cable between
Logic and Relay PCB.
Still Have a Problem?
Check Connection Output
at Aux Transformer.
Check Power supply to Relay PCB
Check Fuse on Relay PCB
Still Have a Problem?
Replace Logic PCB
Using spare display
connect to Logic PCB
Still Dead
Spare Display
works
Replace
Display
402s Ovens Pt. No. 32Z3522 Issue 5
31
NO
Cold Food
Check Convection
Temperature control
OK
Possible Temperature Sensor Fault.
Assuming sensor Ok then make sure
door Light on logic PCB is on when
door closed. If this is working then
replace Logic PCB.
Also, check that convection motor is
operational
Check Current using clip on current
meter through F7 and F8. When
running Microwave only. You will
need to reset the pre-heat
temperature to 0 and enable manual
control via the profile setting. Make
sure that there is a water load in
the cavity.
Less than
5 Amps
More than
5 Amps
Check that the
stirrer is rotating.
Yes
No
Carry out Microwave Output Test
LOW
Check Microwave Generating system
• Transformer
• Magnetron
• Capacitor
• Diode
402s Ovens Pt. No. 32Z3522 Issue 5
Replace stirrer motor
and retest
OK
Contact Merrychef Service
Department for Further
assistance.
32
Cavity Sensor Error
OK
Re-Start Oven
Activate Pre-heat
Is Led D19 on
relay PCB ON
Are there any Signs of
Cavity Fire
NO
Check Temperature
Sensor Resistance
Yes LED is on.
YES
NOT
OK
Report to
Management and
Make Investigation
Replace Sensor
Retest and calibrate
Oven.
N
Check door Switch
LED on logic PCB
LED is on
N
Check the Door Interlock
Switch.
Check The interconnecting
lead to the logic PCB.
Cavity Sensor error is caused by one of the
following :-
1. The cavity did not heat by 180°F in the 10 Minutes
2. The cavity exceeded the set point when cooking by
more than 72°F whilst cooking which indicates that
the food load was on fire
Check Heater
Elements
Replace if necessary
Is the
temperature
display saying
too hot ?
Assume the Cavity is
not too hot then:
Replace Sensor
402s Ovens Pt. No. 32Z3522 Issue 5
33
Magnetron / Overheat issues
Remove and Clean Air Filters.
If Dirty—Advise operating staff of the need
for this to be carried out on regular basis.
See User Manual
Still have a problem.
Check Location of oven is away from any
major heat sources.
Recommend re-location if necessary
Location fine and still have a problem.
Check cooling fan operation. Make sure there is Noticeable airflow from
air vents at the rear of the oven.
If Not investigate and replace cooling fan if necessary.
Fan is fine and I still have a problem.
Note :- Each Magnetron
has a thermistor attached
to it. The control unit will
produce an error if the
temperature exceeds
235°F.
Establish if the magnetron
is actually getting hot.
Remember to take care
given the High Voltage in
the magnetron area.
Check sensor
connections.
Replace Magnetron.
Error reported =
Magnetron or
Ambient
Less than 110°F
Check 15 ribbon Cable
Replace Relay PCB.
Ambient Magnetron
The Ambient Air Sensor is located on the
Relay PCB. Measure the temperature in
the area with all the case work in place
using a Thermocouple Meter
Temperature
reading
Cooling Air Flow
Problem into control
Ambient Conditions
too hot
More than
110°F
area.
402s Ovens Pt. No. 32Z3522 Issue 5
34
APPENDIX 1: TEMPERATURE SENSOR RESISTANCE DATA
Temperature Sensor Resistance
Temp °F Temp °C Min. Rate
kΩ
212 100 11.490 13.060 14.810
302 150 2.803 3.161 3.434
392 200 0.950 1.000 1.050
482 250 0.3572 0.3865 0.4171
Standard
Rate kΩ
Max. Rate
kΩ
R(200)°C = 1 kΩ ± 5%
Note:
These resistances will only be apparent in a stable cavity temperature as the
sensor has a slow response time.
402s Ovens Pt. No. 32Z3522 Issue 5
35
402s Ovens Pt. No. 32Z3522 Issue 5
36
402s Ovens Pt. No. 32Z3522 Issue 5
37
APPENDIX 3: Cool Down Procedure
To cool down and clean a hot oven
Action EC402s V2.0 EC 402s V3.0
To commence Cool Down
procedure Press
Place Ice in cavity COOL DOWN MODE
Press
The oven cools down for
approximately 30 minutes
Cycle ends COOL DOWN COMPLETE
PLACE ICE IN CAVITY
Continue
COOL DOWN MODE
OVEN HOT
PLEASE WAIT
( Also in Spanish)
READY FOR CLEANING
COOL DOWN MODE
PLACE LOAD IN CAVITYAND
PRESS START
Start
COOL DOWN MODE
OVEN HOT
PLEASE WAIT
Turn oven off and ensure
Air Filters are clean
Switch oven off ready for
cleaning
402s Ovens Pt. No. 32Z3522 Issue 5
38
402s Ovens Pt. No. 32Z3522 Issue 5
39
402s Ovens Pt. No. 32Z3522 Issue 5
40
APPENDIX 4: Recommended spares lists USA
Part No. Description Qty Unit
11H0010 HT DIODE ASSY 2 EA 2 2 2 6 12 72
11K0004 RELAY PCB 1 EA 1 1 3 6 36
11M0117 DC VOLTAGE CONNECTOR 10 WAY 1 EA 1 1 1 3 6 36
11Z0298 15 WAY 0.1 RIBBON CABLE ASSY 1 EA 1 1 1 3 6 36
30Z0217 FUSE 1in 10A HRC 5 EA 5 5 5 15 30 180
30Z0231 FUSE HOLDER 1IN (13A) 3 EA 3 3 3 9 18 108
30Z0957 FUSE 1x1/4in 1A HBC (MAINS) 1 EA 1 1 1 3 6 36
30Z1339 FILTER 16A 2 EA 2 2 2 6 12 72
30Z1155 BLOCK TRANSFORMER B0012024 1 EA 1 1 3 6 36
30Z1171 MAGNETRON PANASONIC 2M244 2 EA 1 2 2 6 12 72
30Z1177 20 AMP LITTELFUSE FLM020 4 EA 4 4 4 12 24 144
30Z1178 30A FUSE HOLDER 4 EA 2 4 4 12 24 144
30Z1230
30Z1251 0.88uF 2500V (60Hz Model) 2 EA 2 4 2 6 12 72
30Z1294 MICROSWITCH WITH ROLLER 4 EA 2 2 2 6 12 72
30Z1295 MAGNETRON COOLING FAN 1 EA 1 1 3 6 36
30Z1298 CAPACITOR - MOTOR START - 2uF 1 EA 1 1 3 6 36
30Z1299 DISPLAY ASSY + HEADER 1 EA 1 1 3 6 36
SA234 THERMISTOR SENSOR 50K NTC 2 EA 2 2 2 6 12 72
30Z1315 THERMISTOR 150MM + LEAD 900MM 1 EA 1 1 1 3 6 36
30Z1318 2 POLE ROUND ROCKER SWITCH 1 EA 1 1 1 3 6 36
30Z1293 MOTOR SPEED CONTROLLER 1 EA 1 1 3 6 36
31Z0186 DOOR SEAL SEALANT - 1 TUBE 1 TUBE 1 1 2 6 12 72
31Z0527 STIRRER COVER - SEALANT 1 TUBE 1 TUBE 1 1 2 6 12 72
31Z1247 MICROSWITCH SPRING INTERLOCK 1 EA 1 1 1 3 6 36
32Z4028 COOL DOWN TRAY 1 EA 2 6 12 72
DV0037 BOTTOM TRIM 1 EA 1 1 2 12
DV0055 MEMBRANE PANEL V2.0 - 2.5 1 EA 1 1 3 6 36
DV0091 SIDE PANEL L/H 1 EA 1 1 2 12
DV0092 SIDE PANEL RH 1 EA 1 1 2 12
DV0187 TOP TRIM 1 EA 1 1 2 12
DV0305 DOOR SEAL 402s 1 EA 1 1 2 6 12 72
DV0203 SEAL - CERAMIC COVER 2 EA 2 2 2 6 12 72
DV0254 MEMBRANE PANEL V3.0 1 EA 1 1 3 6 36
DV0275 RACK V3.0 1 EA 1 3 6 36
DV0492 STIRRER COVER - CERAMIC 2 EA 2 2 2 6 12 72
DV0576
DV0606
DV0607
SA111 DOOR ASSEMBLY V2.0 V3.0 1 EA 1 1 2 12
SA208 HOT AIR MOTOR ASSY 1 EA 1 1 3 6 36
SA217 ELECTRICAL SUPPLY LEAD ASSY 1 EA 1 1 2 4 24
SA231 LOGIC BOARD MAIN ASSY 2.0 & 2.5 1 EA 1 1 3 6 36
SA238 STIRRER MOTOR 1 EA 1 1 3 6 36
SA260 LOGIC BOARD MAIN ASSY V3.0 1 EA 1 1 3 6 36
SA276 AIR FILTER 2 EA 2 2 2 6 12 72
SA314 CATALYST ASSY UPPER 1 EA 1 1 1 6
SA315 CATALYST ASSY LOWER 1 EA 1 1 1 6
SA329 REAR PANEL 1 EA 1 1 2 12
SA339 GREASE FILTER HOUSING 1 EA 1 1 2 12
SA340 GREASE FILTER CARTRIDGE 1 EA 1 1 2 3 18
TRANS MULTI 208 220 240 60HZ
HEATER ELEMENT 208V
HEATER ELEMENT 220V
HEATER ELEMENT 240V
2 EA 1 2 2 6 12 72
5 EA 3 5 5 15 30 180
5 EA 3 5 5 15 30 180
First
Aid Kit
Service
Kit
1-5
Ovens
5-50
Ovens
50-100
Ovens
Piece Qty for
600 Ovens
402s Ovens Pt. No. 32Z3522 Issue 5
41
APPENDIX 5: LOGIC PCB Connection Points and key features.
Spare input
not used
Display
Door
Switch IP
Door switch
Indicator
ON when door
closed
Remote data
point
Connecter
Temp Calibration
Relay PCB 15 way
Connecter
MenuKey
Sockect
Connector
Program
memory storage.
May be
exchanged
with New PCB if
PCB replaced.
Motor speed
controller
Membrane panel
connector
D7 Power LED
Indicates Logic PCB
is powered
See Troubleshooting
Guide
402s Ovens Pt. No. 32Z3522 Issue 5
42
APPENDIX 5: Relay PCB Connection Points and key features.
D15 Magnetron
Cavity
Temperature
Sensor
Input
active
D16 Magnetron
soft start
Magentron
Overheat sensor
Inputs
Connector To
Logic PCB
U1 Ambient air
temperature
sensor
Display
Fuse
AC input from
Aux Transformer
D19 Heater ON
D20 LED
ON
when power is on
OFF
when Microwave is
operated.
Fuse
Not Used
Piezo sounder
output
402s Ovens Pt. No. 32Z3522 Issue 5
43
APPENDIX 6: Engineering Test Settings
Engineering Test Settings - Changing the Oven Profile
In order to carry out an oven test procedure the oven PREHEAT must be set to 0ºF/OFF to
switch off the convection heaters and the Manual controls must be enabled.
When the test is completed the oven must be returned to its original settings or the
appropriate MenuKey can be used to reset the oven automatically.
To set the PREHEAT temperature to 0ºF/OFF
402s Version 3.0 models
1. Switch the oven OFF
2. Switch ON and immediately press Edit Preheat
Temp.
402s Version 2.0/ 2.5
1. Switch the oven OFF
2. Switch ON and
immediately press
Edit Preheat to show
the ENTER
PREHEAT TEMP
screen.
3. Make a note of the Preheat temperature in
3. Make a note of the Preheat temperature in the
the display.
display.
4. Press 0, 0, 0 to overwrite the current
temperature setting.
Then press Save to
store this setting
Press +>> for OFF
( note pressing either +>> or << - will cycle
through all the available temperatures)
Then Press Save to store this setting
To set the Oven controls to allow Manual operation
1. Switch the oven OFF then
2. Switch ON and immediately press the lower right
pad to display the OVEN PROFILE screen.
3.
Press to set Manual Mode to
ON
Then Press
Save
1. Switch the oven OFF
2. Switch ON and
immediately press
Profile to edit the oven
operating profile
3. Press Change to set
OVEN MODE to
PROGRAM/MANUAL
merrychef
Edit Preheat
ENTER PREHEAT TEMP
Profile
000ºF
Save
merrychef
Change
OVEN MODE
PROGRAM/MANUAL
Change
Profile
Next
To use Manual Mode: from the CATEGORIES
standby screen press the lower centre right pad
To display the Manual mode screen.
402s Ovens Pt. No. 32Z3522 Issue 5
Then press Next five times to return
to the OVEN COLD standby screen.
To use MANUAL MODE:
from the OVEN COLD/PRESS PREHEAT
standby screen press the PREHEAT/
COOL DOWN pad on the control panel
and then press Manual.
44
READY
TO COOK AT 000ºF
Manual
Run Prog
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