Merrychef s Parts Manual

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32Z3539 Issue 4

402s

SERVICE& PARTS MANUAL

SERVICE MANUAL

CAUTION MICROWAVE EMISSIONS

DO NOT BECOME EXPOSED TO EMISSIONS FROM THE MICROWAVE

GENERATOR OR PARTS CONDUCTING MICROWAVE ENERGY

This manual covers UK/EC models manufactured from:
Version 2.0 Serial No. 000745 –001199
Version 3.0 Serial No. 001200 onwards

ISSUE 4

01.05.2008

Merr ychef

Version 3.0

Version 2.0

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32Z3539 Issue 4

Safety code..............................................................................3

Product specifications..............................................................4

Installation instructions ............................................................5

Main features ...........................................................................6

Main features control panel Version 2.0 ..................................7

Main features control panel Version 3.0 ..................................8

Principal components: RHS.....................................................9

Principal components: LHS ...................................................10

Principal components: Control Box .......................................11

Principal components: Back View .........................................12

Principal components: Power Supply ....................................13

Principal components: Cavity Parts & KFC Accessories ......14

Principal components: External panels & Parts.....................15

Principal components: Electronic control panel assembly.....16

Parts matrix...................................................................... 17-18

Procedure for Power output measurement............................19

Procedures for Principal Component tests ..................... 20-21

Procedure for door interlock adjustment.......................... 22-23

Hot Air Motor and controller............................................. 24-25

Circuit Diagram ................................................................ 26-33

Troubleshooting Guide .................................................... 34-38

Appendix 1: Temperature Sensor resistance data ................39

Appendix 2: MenuKey download procedure V2.0 .................40

MenuKey download procedure V3.0 .................41

Appendix 3: Cool down & Cleaning Procedure ............... 42-44

Appendix 4: Recommended Spares List ...............................45

Appendix 5: PCB connection Points ................................ 46-47

Appendix 6: Firmware revision guide............................... 48-53

Appendix 7: Electrical Installation Guide ...............................54

TABLE OF CONTENTS

Merrychef Limited,
Station Road West,
Ash Vale, Aldershot
Hampshire GU12 5XA
United Kingdom
Tel: [phone] Fax: [phone]
Internet address: http://www.merrychef.com
E-mail: [e-mail] or [e-mail]

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32Z3539 Issue 4

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 M: 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.

x Switch off the mains supply and remove the plug from the wall socket.

or

x 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:

x All internal electrical connections are correct (see wiring diagram).
x All wiring insulation is correct and is not touching a sharp edge.
x All grounding connections are electrically and mechanically secure.
x All door safety interlocks are secure and mechanically sound.
x The door operation is smooth, and the arms run freely in the slots.
x The door activates all four of the door interlock switches and in the correct order
x The temperature sensor is correctly connected to the Power PCB.

Before finishing a service call, recheck the following points:

x All of the electronics are functioning correctly and all of the touch pads are working.
x Microwave emissions are below permissible limit of 5 mW/cm².
x The power output of the oven is checked in accordance with the procedure page.
x Oven has correct 50mm (2 inches) air gap all round and 50mm (2 inches) above.

Air flow should not be restricted.

SAFETY CODE

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32Z3539 Issue 4

Power
Requirement

See Rating Label

Power Output Microwave 100%

Convection

1500watts
3250watts

External
Dimensions

Height

Width

Depth

595mm (23.0 inches)

585mm (23.0 inches)

700mm (27.5 inches)

Weight Nett 90kg ( 198lb.s )

Construction Cavity

Casework

304 Stainless Steel

PRODUCT SPECIFICATIONS

Supply

Voltage

Freq.

Hz

Phase/Supply

Control

Type

Type

Country
/Region

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)

D =
2 P + Gnd (30 Amps)

K =

Electronic
MenuKey

1

2
3

GM =

General
Market

UK =

United
Kingdom

US =

USA

EU =

Europe

Model Number: 402S VVV F P C R TT ZZ

Example 402S2205BK2GMEU

Model No. EC402s
220V, 50Hz, L1 +L2 +N +Earth supply, MenuKey Revision 1, General Market, EU

Version

Serial Number (Rating Plate):

Month 00/ Year 00/ Production number 00000

e.g 01 08 03349 Oven manufactured January, 2008, production number 03349

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32Z3539 Issue 4

Installation Instructions for Mealstream 402s Ovens

Power Supply Requirements

The Mealstream 402s 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 3mm ( 1/8 inch ) should be fitted.

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 50 mm ( 2 inches )
clearance at the sides and rear of the oven.

Air intake temperature should not exceed 45°C (110°F )
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.

Note:
The minimum
recommended clearance
required for air flow

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.

INSTALLATION INSTRUCTIONS

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.

Earth Bond terminal

An Earth Bond Terminal is provided on the rear panel of the oven for independent Earth (GND)
connection.

Stacking the oven ( Maximum one only)

Using stacking kit Part No. SA129

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32Z3539 Issue 4

h

DOOR

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.

i

DOOR SEAL

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.

j

ELECTRICAL SUPPLY CORD

Electrical supply cord is situated on the rear of
the oven,

k

AIR FILTERS

Main intake for cooling air for internal
components. Must be clear of obstructions.

m

STEAM VENT PIPE

Vents steam from the oven cavity

L

IMPINGER PLATES ( Upper & Lower)

Direct the air in the cavity. They must be
cleaned on a regular basis, and kept free of
debris

MAIN FEATURES

k

h

d

i

j

a

On/Off SWITCH

This is used to turn the oven On or Off.

IT DOES NOT ISOLATE INTERNAL WIRING
FROM THE MAINS SUPPLY.

b

MenuKey

The MenuKey System automatically changes
all the cooking programs with an electronic key
and allows program names to be identified.

c

OVEN CAVITY

The oven cavity is mainly constructed from
stainless steel panels. It must be kept clean.

d

GREASE FILTER

The grease filter must be cleaned on a regular
basis, and kept free of debris.

e

RACK

The cooking rack should be removed daily and
cleaned

f

HOT AIR FAN

Situated behind the grease filter and circulates
the hot air through the cavity.

g

RATING PLATE

The rating plate is situated on the rear of the
oven, and states the Model, Serial Number,
Electrical Ratings and Manufacturers
telephone number.

e

L

f

b

g

k

c

a

L

m

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32Z3539 Issue 4

Electronic control panel: Version 2.0

MAIN FEATURES

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

POWER PADS

FAN SPEED PADS

CANCEL
PAD

MAIN DISPLAY
PANEL

MenuKey

PROGRAM

TIME/ PROGRAM PADS

PREHEAT/ COOL DOWN

FUNCTION
PADS

START

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

Message Condition Possible cause

ERROR MAGNETRON 1 Magnetron 1 has overheated Blocked Air filter(s)

Oven located near hot air sources
Oven being used empty
Cooling fan failure
Magnetron failure

ERROR MAGNETRON 2 Magnetron 2 has overheated

ERROR MAGNETRON 1 & 2 Magnetron 1 and 2 have overheated

CAVITY SENSOR ERROR Cavity temperature exceeds more

than 50°C above PREHEAT
temperature setting during cook cycle

Indicates combustion ( fire ) in oven cavity
Note: In service operations when
PREHEAT is set to 0°C this message can
appear when the oven is operated

Display Panel error messages

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32Z3539 Issue 4

Electronic control panel: Version 3.0

MAIN FEATURES

CANCEL
PAD

MAIN DISPLAY
PANEL

MenuKey

COOL DOWN

FUNCTION
PADS

FUNCTION
PADS

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.

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

Display Panel error messages

Error Message Condition Possible Cause

Magnetron 1 Overheat
Ensure air filters are clean
Allow oven to cool

Magnetron 1 has overheated Blocked air filters

Oven located near hot air source
Oven being used empty
Cooling fan failure
Magnetron failure

Magnetron 2 Overheat
Ensure air filters are clean
Allow oven to cool

Magnetron 2 has overheated

Magnetron 1 & 2 Overheat
Ensure air filters are clean
Allow oven to cool

Magnetron 1 & 2 have overheated

Magnetron 1 Failure Magnetron 1 no microwave output

Magnetron 2 Failure Magnetron 2 no microwave output

Magnetron 1 & 2 Failure Magnetron 1 & 2 no microwave

output

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 295°C

Blocked air filters
Restricted airflow to air filters
Combustion (fire) in cavity

Heater Failure Cavity has not reached a

temperature of 100°C in 10 minutes

One or more heater elements have failed
and need to be replaced

Check power supply
Magnetron failure

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PRINCIPAL COMPONENTS: Right Side

No. Description Part No.

1 Cavity Overheat stat 30Z1024

2 Motor Start Capacitor 2µF ( Blue ) 30Z1298

3 Filter 16A (Threaded) 30Z1340

4 Air filter SA276

5 Stirrer motor Assembly SA288

6 Microswitch SW1

Microswitch SW2

30Z1294

7 Door Hinge Assembly RH SA202

8 Magnetron Cooling Fan 30Z1295

26 HV Capacitor 2500V 1.1ȝF ( 50HZ models ) 30Z1242

26 HV Capacitor 2500V 0.88ȝF ( 60HZ models ) 30Z1251

26A HV Capacitor universal clip 31Z1261

70 Fibre Optic PCB 11M0364

71 Solid State Relay 30Z1362

1

3

4

5

6

7

8

26

6

26A

2

70

71

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32Z3539 Issue 4

PRINCIPAL COMPONENTS: Left Side

No. Description Part No.

3 Filter 16A (Threaded) 30Z1340

4 Air filter SA276

5 Stirrer motor Assembly SA288

6 Microswitch SW3

Microswitch SW4

30Z1294

9 Door Hinge Assembly LH SA203

10 Motor Controller 30Z1319

24 Thermistor Cavity 30Z1315

25 HV Capacitor 2500V 1.0ȝF ( 50Hz models ) 30Z1331

25 HV Capacitor 2500V 0.88ȝF ( 60Hz models ) 30Z1251

25A HV Capacitor clip 31Z1261

70 Fibre Optic PCB 11M0364

3

25

25A

5

6

9

10

4

6

70

24

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32Z3539 Issue 4

PRINCIPAL COMPONENTS: Control Box

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 11K0002

16 Logic PCB Assembly Version 3.0 11K0012

17 Transformer LT (Low voltage) 30Z1155

18 Fuse 1A 30Z0957

59 Sounder SA257

72 Fibre Optic Logic PCB 11K0013

11

13

12

14

15

18

17

16

See

Principal

components:

POWER

SUPPLY

11

59

72

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32Z3539 Issue 4

PRINCIPAL COMPONENTS: Back view

No. Description Part No.

20

Heater Element 220V 650W

DV0606

20

Heater Element 240V 650W

DV0607

21 Magnetron (Toshiba) 30Z1349

22 Magnetron Thermistor Assembly SA234

23 Convection ( Hot Air ) Motor Assembly SA208

27

Transformer 208/220/240V 50Hz

30Z1233

27

Transformer 208/220/240V 60Hz

30Z1230

28 HT Diode Assy PCB (Fibre Optic) 11H0364

28A HT Diode Assembly ( Non-optic) 11H0010

73 Magnetron Cooling Duct LH DV0039

74 Magnetron Cooling Duct RH DV0040

21

23

20

27

21

22

22

28A

27

28

74

73

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32Z3539 Issue 4

PRINCIPAL COMPONENTS: Power Supply

N1 L1 L2

Electrical Supply: Twin phase
2P+N+Earth

No. Description Part No.

3 Filter 16A 30Z1340

11 Fuse 10A HRC 30Z0217

19

Cable Gland 31Z0500

Cable Gland Nut 31Z0499

29 Electrical Supply Lead Assembly Single Phase SA226

30 Terminal Block 31Z0447

31 Fuse 20A FLM 30Z1177

32 Fuse Holder 30A 30Z1178

34 Fuse Holder 10A 30Z0231

29A Electrical Supply Lead Assembly Twin Phase SA225

29A

Electrical Supply: Single Phase

19

29

30

3

31

11

32

34

29

29A

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32Z3539 Issue 4

PRINCIPAL COMPONENTS

No. Description Part No.

5A Stirrer (behind stirrer glass) SA291

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

No. Description Part No.

60 Cool-down pan 32Z4028

61 Oven tray MC3175

62 Handle Assembly SA267

64 Griddle carrier SA350

65 Chicken Griddle (SA350 + DV0221 + DV0267) SA133

63 Griddle DV0221

KFC Accessories

60

61

62

63

64

65 Chicken Griddle SA133

* Parts 35 & 37 Contact Service Department

Cavity

35

36

38

36

39

40

5A

Stirrer glass
Shown removed

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32Z3539 Issue 4

External Parts

PRINCIPAL COMPONENTS

No. Description Part No.

4 Air Filter SA276

41 Top Panel 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

Door Seal (wide) DV0305

Door seal sealant ( tube ) 31Z0186

50 Bottom Trim DV0037

51 Side Panel RH DV0092

52 Door Assembly SA111

49

Control Panel

See page 16

52

51

50

41

48

4

42

43

4

49

47

Door Assembly

45

46

52

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32Z3539 Issue 4

Electronic Control Panel Assembly

PRINCIPAL COMPONENTS

No. Description Part No.

53 MenuKey Dust Cover DV0052

54 Power switch (On/Off) 30Z1318

55 GM Membrane Version 2.0 DV0055

57 Display Assembly & Header Version 2.0 30Z1299

68 Display Assembly & Header Version 3.0 30Z1324

56 Front Panel Version 2.0 DV0036

58 MenuKey Socket 11K0005

66 GM Membrane Version 3.0 DV0254

67 Front Panel Version 3.0 DV0249

53

54

Version 2.0

58

57

56

53

54

58

68

67

Version 3.0

66

55

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32Z3539 Issue 4

Ref. No. Description Part No.

1 Cavity High limit Stat 30Z1024

2 Motor Start Capacitor 2µF ( Blue ) 30Z1298

3 Filter 16A 30Z1340

4 Air filter SA276

5 Stirrer motor Assembly SA288

5A Stirrer (inside cavity) SA291

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 30Z1319

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 Version 2.0/ 2.5 11K0002

16 Logic PCB Assembly Version 3.0 11K0012

17 Transformer LT (Low voltage) 30Z1155

18 Fuse 1A 30Z0957

19 Cable Gland 31Z0500

Cable Gland Nut 31Z0499

20

Heater Element 220V 650W

DV0606

Heater Element 240V 650W

DV0607

21 Magnetron (Toshiba)

30Z1349

22 Magnetron Thermistor Assembly

SA234

23 Convection ( Hot Air ) Motor Assembly

SA208

24 Thermistor Cavity

30Z1315

25

HV Capacitor 2500V 1.0ȝF ( 50Hz Models)

30Z1331

25

HV Capacitor 2500V 0.88ȝF ( 60Hz Models )

30Z1251

25A HV Capacitor clip universal

31Z1261

26

HV Capacitor 2500V 1.1ȝF (50Hz Models)

30Z1242

26A HV Capacitor clip universal

31Z1261

27

Transformer 208/220/240V 50Hz

30Z1233

27

Transformer 208/220/240V 60Hz

30Z1230

28 HT Diode Assy

11H0010

29 Electrical Supply Lead Assembly

SA226

29A Electrical Supply Lead Assembly Twin Phase

SA225

30 Terminal Block

31Z0447

31 Fuse 20A FLM

30Z1177

Part number identification chart 1

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32Z3539 Issue 4

Ref.

No.

Description Part No.

32 Fuse Holder 30A 30Z1178

34 Fuse Holder 10A 30Z0231

35 Grease Filter ( 2 parts ) SA339

SA340

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 (wide) 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 GM Version

Version 2.0

DV0055

56 Front Panel Version 2.0 DV0036

57 Display Assembly

& Header Version 2.0

30Z1299

58 MenuKey Socket

11K0005

59 Sounder

SA257

60 Cool-down pan

32Z4028

Part number identification chart 2

Ref.

No.

Description Part No.

61 Oven tray MC3175

62 Handle Assembly SA267

63 Griddle DV0221

64 Griddle carrier SA350

65 Chicken Griddle

(SA350+DV0221+ DV0267)

SA133

66 GM Membrane Version 3.0 DV0254

67 Front Panel Version 3.0 DV0249

68 Display Assembly

Header Version 3.0

30Z1324

70 Diode Assembly 11M0364

71 Solid State Relay 30Z1632

72 Fibre Optic Logic PCB 11K0013

73 Magnetron Cooling Duct LH DV0039

74 Magnetron Cooling Duct RH DV0040

— Door seal sealant ( tube ) 31Z0186

— Stirrer cover sealant ( tube ) 31Z0527

— Grease Filter Cartridge SA340

— Microswitch interlock Spring 31Z1247

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32Z3539 Issue 4

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:

PROCEDURE FOR POWER OUTPUT MEASUREMENT

1. Fill one beaker ( glass or plastic ) with one litre ( 1.78 pints ) of tap water
at about 20ºC( 68ºF ) and measure the water temperature.
( Use a thermometer with a

1

/10, 0.1 degree gauge ).

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 10%.

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
15ºC ( 27ºF ) Minimum
20ºC ( 36ºF ) Maximum

Ensure the oven is cold before commencing the test

Before this test is carried out the oven PREHEAT temperature must be set to 0ºC as this enables
the oven to be used in Microwave ONLY mode. On completing the test the Oven PREHEAT
temperature should be restored to its previous setting.

EC402s Version 2.0 To set the PREHEAT temperature to 0ºC

1. Switch the oven on and immediately press the Edit Preheat function key, the ENTER
PREHEAT TEMP screen will display ( Note this screen is available for 5 seconds )

2. The oven display shows the current PREHEAT setting, make a note of this temperature

3. Enter 0,0,0 for 0ºC and press Save.

4. The display will now show the initial Edit Preheat/Profile screen for 10 seconds then the cold
standby screen.
Press the PREHEAT pad, the oven will not preheat but the READY TO COOK screen will
appear in the display.

Note:
Power Output is affected by the line voltage under load.
For correct Power Output measurement the line voltage under load must be correct.

Test procedure:

EC402s Version 3.0

To set the PREHEAT temperature to 0ºC

1. Switch the oven on and immediately press the Edit Preheat Temp function key, the OVEN
TEMPERATURE screen will display ( Note this screen is available for 5 seconds )

2. The oven display shows the current PREHEAT setting, make a note of this temperature

3. Hold down the

<< — for 0ºC and press Save.

4. The Categories screen will appear in the display.

Manual Mode:

If this screen does not appear
MANUAL MODE is set to OFF and
must be changed to ON in the oven
PROFILE.

Version 3.0

Switch Oven OFF then ON and im­mediately press the lower of the 4
pads on the RHS of the display. In
OVEN PROFILE change Manual
Mode to ON

Version 2.0

Switch Oven OFF then ON and
immediately press the Profile
pad. Press change to set OVEN
MODE to PROGRAM/MANUAL

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32Z3539 Issue 4

1. Power Transformer Test

You will need:

A Digital Multi-meter (D.M.M.)
A Megger or similar resistance meter using 500V d.c.

PROCEDURES FOR PRINCIPAL COMPONENTS TEST (1)

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:

a Mains winding between tags

Approx. 1.1 :

b High Voltage winding

Approx. 60 :

c Filament winding

between terminals

Less than 1 :

Primary winding and chassis

Pass if over 10 M:

Filament winding and chassis

Pass if over 10 M:

5 Using a Megger, test the insulation resistance between:

One end of the High Voltage winding is connected to the

chassis, so this is not tested.

a

c

b

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.

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.

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
measurements at the High Voltage circuits, including the magnetron filament.

WARNING: Even when the oven is not cooking, the High Voltage Capacitor has High Voltages

present because of the Soft Start circuit. Isolate the oven before testing.

See Safety Code ( Page 3 )

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
measurements at the High Voltage circuits, including the magnetron filament.

WARNING: Even when the oven is not cooking, the High Voltage Capacitor has High Voltages

present because of the Soft Start circuit. Isolate the oven before testing.

See Safety Code ( Page 3 )

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32Z3539 Issue 4

PROCEDURES FOR PRINCIPAL COMPONENTS TEST (2)

3. High Voltage Rectifier Test

You will need:

A Megger or similar resistance meter using 500V d.c.

5. Using a Megger, test the insulation resistance between the
terminals and the case.

Between Terminals

Pass if approximately 10 M:

Between Terminals and Case Pass if open circuit

Between Terminals and Case

Pass if over 100 M:

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

FAIL

Conducts one way only

PASS

Short Circuit both ways

FAIL

Conducts one way, leaks the other

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.

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.

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
measurements at the High Voltage circuits, including the magnetron filament.

WARNING: Even when the oven is not cooking, the High Voltage Capacitor has High Voltages

present because of the Soft Start circuit. Isolate the oven before testing.

See Safety Code ( Page 3 )

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
measurements at the High Voltage circuits, including the magnetron filament.

WARNING: Even when the oven is not cooking, the High Voltage Capacitor has High Voltages

present because of the Soft Start circuit. Isolate the oven before testing.

See Safety Code ( Page 3 )

( High Voltage Capacitor Test continued, ensure steps 1-4 on previous page have been completed)

22

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32Z3539 Issue 4

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.

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:

PROCEDURE FOR DOOR INTERLOCK ADJUSTMENT AND TEST 1

Right Side

Left Side

Monitor

SW1

Primary
SW2

Secondary
SW3

Microswitches

RH side

Door closed

Logic PCB

SW4

Door Interlock Arrangement: Switches shown in Door Closed position

Power In

Power
Out

L1

L2

Secondary

switch

RHS

LHS

Monitor

switch

Primary

switch

Logic

PCB

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32Z3539 Issue 4

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.

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.

Spacer

Door seal

Door

24

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32Z3539 Issue 4

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 inside the motor will
operate and shut down the motor speed controller.

Motor/ controller fault finding

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)

Step

1

2

3

4

5

6

8x 31Z4016
M5 Flange nut

SA208 Hot Air Motor Assembly

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32Z3539 Issue 4

Displays and messages: LED status display

PRINCIPAL COMPONENTS: Hot Air Motor & Controller 2

Power Terminals

Motor Terminals

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

Blue Black Brown

Wire
27

Wire 26

Fan
speed %

Voltage dcRPM Condition

100% 10V 7000 Full

Speed

50% 5V 3500 Door

Closed

20% 2V 1500 Door

Open

Grey wire
to Motor

Blue 0V

Yellow 0-10V

Red +10V

V

Motor Speed and Logic board voltage table

LED Meaning Position

LED Off Inverter Off / No supply

Long On & Off (1sec) Power On / Ready

LED On steadily Inverter Running

Long On (0.5 sec)/ short Off General Warning

Very Short On & Off (0.1sec) Fault Condition

LED

26

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32Z3539 Issue 4

CIRCUIT DIAGRAM: Issue 9

NOTES

FUSE VALUE FUNCTION

F2 20A HEATERS CIRCUIT

F4 20A MICROWAVE / INTERLOCKS

F6 10A CONTROL CIRCUIT

F7 10A TRANSFORMER 2

F8 10A TRANSFORMER 1

F9 1A AUX TRANSFORMER 3

HEATER ELEMENTS

650 WATT PER ELEMENT

CAVITY OH STAT

300C / 572F

LHS SW3

SECONDARY

RHS SW2

PRIMARY

RHS SW1

MONITOR

50

13

07

17

18

19

13

50

19

INTERLOCKS

NOTE: SWITCHES

SHOWN IN DOOR

CLOSED POSITION

07

28

48

28

F9

29

47

t

o

CAVITY

OH STAT

29

CAVITY STAT AND LOW

VOLTAGE TRANSFORMER

T3

T3

COOLING

FAN

BROWN

BLUE

BLACK

2uF

22

M

24

25

25

24

STIRRER MOTOR LHS

20

21

21

20

M

STIRRER MOTOR RHS

MOTORS

MOTOR SPEED

CONTROLLER

27

26

27

26

MSC

BLUE

BROWN

22

23

23

TERMINAL BLOCK

WVU

BLUE

BLACK

BROWN

GREY
GREY

BLUE 0V

YELLOW 0-10V+

RED10V+

10

9

8

6

3

CONVECTION

MOTOR

MICROWAVE

MF5

L2

U1

N4 U3

62

63

55

54

RHS

NOTE TAPPING

F7

45

11

11

15

15

MF4

L2

U1

N4 U3

60

61

53

52

LHS

NOTE TAPPING

F8

46

12

12

14

14

T2

T1

LOGIC BOARD

PCB

DISPLAY

MENUKEY

PCB

MEMBRANE

PANEL

SK1

JP13/14

JP19

SW5

DOOR

INDICATOR

10

4

20

CONTROLS

INTER-

CONNECTOR

NOTE: DOOR

SWITCH SHOWN IN

DOOR CLOSED

POSITION

JP15

MSC

JP18

JP20

01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16

171819

21

23

25

27

29

31

20

22

24

26

28

30

21

20

25

24

22

23

27

26

30

31

30

31

28

29

6

04 05 06

220 OHMS

11 12 14

15

18

191817

7

13

07

CAVITY SENSOR

MAG LHSSENSOR

MAG RHSSEN SOR

RELAY BOARD

T3

16

16

HEATERS MICROWAVE

JP3

JP2

JP1

JP5

11 12

28

1513 14

19

17

54

292627242522232021

INTER-

CONNECTOR

F4

F6

F2

49

5

4

35

36

38

40

32

33

MF1

L2

U1

N4 U3

MF2

L2

U1

N4 U3

42

MF3

L2

U1

N4 U3

44

56

51

HEATERS / MAINS SWITCH

SW4

31

30

MAINS ON/OFF

SWITCH SHOWN IN

OFF STATE

34

30

31

50

16

4

5

33

32

35

36

34

38

L3

L2

L1

37

BLACK

WHITE

MAINSIN

MAINS IN

34

33

32

NC

38

35

36

L2

L1

N

37

BLUE

BROWN

MAINSIN

EUROPE/REST OF WORLD

34

33

32

NC

38

35

36

BLACK

NORTH AMERICA

REMOVE WIRE 37 FOR

TWIN PHASE WIRING

TWIN

PHASE

17

18

Part No. 32Z3517

Issue 9

NOTE: USE 208V TAPPING FOR

208V OVEN. ALL OTHER

VOLTAGES USE 230V TAPPING

5

5

6

60Hz HEATER

50Hz HEATER

49

49

57

50Hz OVEN FIT WIRE 57.

CABLE TIE WIRE 4 TO LOOM

49

6

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32Z3539 Issue 4

CIRCUIT DIAGRAM: Issue 10

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CIRCUIT DIAGRAM: Issue 11

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32Z3539 Issue 4

CIRCUIT DIAGRAM: Issue 12

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32Z3539 Issue 4

CIRCUIT DIAGRAM: Issue 13

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32Z3539 Issue 4

CIRCUIT DIAGRAM: Issue 14

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32Z3539 Issue 4

CIRCUIT DIAGRAM: Issue 15

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32Z3539 Issue 4

CIRCUIT DIAGRAM: Issue 17

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32Z3539 Issue 4

Note : The following Diagnosis procedures may not expose all possible errors but have

been included for general guidance.

Trouble-Shooting Guide

Standard Electrical Checks

x Check that oven is connected to an

Electricl Power supply and that any trip
that supplies the unit is not switched off.

x Check that the oven is switched on.
x Check the Electricl Power supply voltage

at the input terminal block.

x Check that all fuses are intact.
x 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

.

x 1.0 No Display

x 3.0 Cavity Sensor Error

x 4.0 Magnetron / Over heat errors

Standard Food Quality Checks

x Check that the PREHEAT temperature is

set correctly.
See User Manual.

x Check that the food being cooked has

been stored at the correct temperature.

x Check that the correct program is being

used.

Still Have a problem:

Select a Category.

x 2.0 Cold Food

x 2.0 Core Temperatures Low

Is the problem Food Quality or Fundamental

Operational Issue?

Food Quality

Fundamental

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32Z3539 Issue 4

Check cable from logic PCB to

display is in place and no obvious

wires are disconnected or shorted.

Still Have a problem?

Using spare display

connect to Logic PCB

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?

1.0 No Display

ON

Is Logic PCB

Active ?

See D7 LED

OFF

Is Relay PCB

Active see D27

OFF

ON

Still Dead

Spare Display

works

Replace

Display

Replace Logic PCB

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32Z3539 Issue 4

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.

Check that the

stirrer is rotating.

Replace stirrer motor

and retest

Carry out Microwave Output Test

Check Microwave Generating system

x Transformer
x Magnetron
x Capacitor
x Diode

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

Contact Merrychef Service
Department for Further
assistance.

2.0 Cold Food

Check Convection

Temperature control

OK

NO

Less than
5 Amps

More than
5 Amps

No

Yes

LOW

OK

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32Z3539 Issue 4

Report to
Management and
Make Investigation

Check Temperature

Sensor Resistance

OK

Re-Start Oven

Activate Pre-heat

Is Led D19 on
relay PCB ON

Replace Sensor

Retest

N

Check door Switch
LED on logic PCB

N

Check the Door Interlock
Switch.
Check The interconnecting
lead to the logic PCB.

LED is on

NO

YES

Yes LED is on.

Check Heater
Elements
Replace if necessary

Cavity Sensor error is caused by one of the
following :-

1. The cavity did not heat by 100°C in the 10 Minutes

2. The cavity Exceed the set point when cooking by
more than 40°C whilst cooking which indicates that
the food load was on fire

3.0 Cavity Sensor Error

Are there any Signs of

Cavity Fire

NOT
OK

Is the

temperature

display saying

too hot ?

Assume the Cavity is
not too hot then:
Replace Sensor
Re-test and calibrate

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32Z3539 Issue 4

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.

Error reported =

Magnetron or

Ambient

Ambient Magnetron

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.

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

< 60°C

> 60°C

Cooling Air Flow

Problem into control

area.

Ambient Conditions

too hot

Check 15 ribbon Cable

-

Replace Relay PCB.

Note :- Each Magnetron
has a thermistor attached
to it. The control unit will
produce an error if the
temperature exceeds
130°C.

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.

4.0 Magnetron / Overheat issues

Temperature

reading

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32Z3539 Issue 4

APPENDIX 1: TEMPERATURE SENSOR RESISTANCE DATA

Temp °F Temp °C Min. Rate

kȍ

Standard

Rate kȍ

Max. Rate

kȍ

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

R(200)°C = 1 kȍ ±5%

Temperature Sensor Resistance

Note:
These resistances will only be apparent in a stable cavity temperature as the
sensor has a slow response time.

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32Z3539 Issue 4

APPENDIX 2: MenuKey, changing oven menus

1

1

2

3

Lift the MenuKey cover in the
top front panel of the oven and
put the key in the slot.

The MenuKey System automatically changes all the cooking programs
on the oven from a pre-programmed electronic key.

To change the menus on the oven:

Ensure the power switch is OFF.

With the key still in place switch
the power switch ON.
The oven will now go through the
program download sequence by
displaying the following:

MENUKEY2

The MenuKey Code. e.g. 555

The MenuKey CS e.g.
0A06
MenuKey CS (checksum)
confi rms the menus on this key
are valid for the MenuKey Code.

Confi rm that the MenuKey Code
and MenuKey CS are correct
and press Download Function
key to load the programs into the
Oven memory.

MENUKEY2 DETECTED

Download Upload

MK CODE 555
MK CS 0A06

Download

4

MENUKEY2 DETECTED

Download Upload

MK CODE 555
MK CS 0A06

WARNING

Exit Continue

ALL OVEN PROGRAMS

WILL BE OVERWRITTEN

Note: Downloading from a
MenuKey will clear all the
existing programs

Continue

Check that the key is correct
then press the Continue
function key to proceed with the
Download

MENUKEY2 DOWNLOAD

COMPLETE

Exit

CHECKSUM:0A06

Exit

On completion of the download
press the Exit function key to
return the oven to standby mode.

Remove the MenuKey and keep
in a safe place.

OVEN COLD

PRESS PREHEAT

.
Model No. 402S
Software
MK serial No.

The display briefl y will show the
following:

Oven Model No. Software
& MenuKey serial No.

The standby screen will then
display

Do not remove the key

during download sequence

as this could corrupt

the data on the key

MENUKEY2

DOWNLOADING

MENUKEY2

VERYIFYING

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32Z3539 Issue 4

APPENDIX 2: MenuKey, changing oven menus

17

1

2

3

Lift the MenuKey cover in the top front panel of
the oven and put the key in the slot.

The MenuKey System automatically changes all the cooking programs
on the oven from a pre-programmed electronic key.

To change the menus on the oven:

Ensure the power switch is OFF.

With the key still in place switch the power switch ON.
The oven will now go through the program download
sequence by displaying the following:

MENUKEY2

MenuKey Detected

Please Wait

WARNING
Downloading from a MenuKey will clear
all the existing programs

Check that the key has the correct
number/code for the programs you want
to load into the oven memory

Do not remove the key

during download sequence

as this could corrupt

the data on the key

Copying Programs from

MenuKey to Oven

Remove the MenuKey and keep in a safe place.

The display briefl y will show the following : Oven Model No., Software & MenuKey serial No.
The Oven will then commence heating up to the PREHEAT temperature ready to cook.

Verifying Programs

Copied Correctly

MenuKey Copied

Successfully

4

Saving Programs to a MenuKey

EDIT CATEGORY NAME

CREATE MENUKEY

EDIT A PROGRAM

EDIT

CAT 005

CAT 006
CAT 007
CAT 008

CAT 001

CAT 002
CAT 003
CAT 004

CATEGORIES

In the CATEGORIES screen select EDIT SCREEN ( Pad name hidden) then select CREATE MENUKEY

Copying Programs from

Oven to MenuKey

Verifying Programs

Copied Correctly

MenuKey Copied

Successfully

The Display returns to the CATEGORIES screen and the Oven will heat up to the PREHEAT
temperature ready to cook.

Set the Program Mode to ON or OFF,
Set Manual Mode to ON or OFF:
Enter the Lower Band temperature setting 15-75°C
Set the oven Temperature Scale °C

1

2
3
4

EDIT SCREEN

5

Insert a MenuKey and press START to copy the programs.
The display shows the following:

For an explanation of the following features see
Setting the Oven Profi le Page 11

Enter a number for the MenuKey Code to identify
the new MenuKey, use the +/- Function Pads.

WARNING

Any programs already

on the key will be deleted

START

MenuKey Code: 000

Program Mode : ON

Temperature Scale : °C

Cooking Range: OFF

Cooking Range: OFF

MENUKEY PROFILE

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32Z3539 Issue 4

APPENDIX 3: Cool Down Procedure

Action EC402s V2.0 EC 402s V3.0

To commence Cool Down
procedure Press

Place Ice in cavity COOL DOWN MODE

PLACE ICE IN CAVITY

COOL DOWN MODE

PLACE LOAD IN CAVITYAND

PRESS START

Press

Continue

The oven cools down for
approximately 30 minutes

COOL DOWN MODE

OVEN HOT

PLEASE WAIT

( Also in Spanish)

COOL DOWN MODE

OVEN HOT

PLEASE WAIT

Cycle ends COOL DOWN COMPLETE

READY FOR CLEANING

Turn oven off and ensure

Air Filters are clean

Switch oven off ready for
cleaning

To cool down and clean a hot oven

Start

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32Z3539 Issue 4

APPENDIX 3: Cleaning procedure 1

20

• ALWAYS switch off at the electrical supply and allow oven to cool before cleaning

• CAUTION: Allow the oven and accessories to cool before commencing cleaning

*When replacing impinger plates and the cavity grease fi lter
use fi rm fi nger pressure to tighten fasteners
DO NOT USE TOOLS

DO NOT
USE TOOLS

WARNING: DO NOT use caustic cleaners on any part of the oven or oven
cavity as it will cause permanent damage to the Catalytic Convertors

DO NOT spray directly into the fan opening at the rear of the oven

Equipment: Merrychef oven cleaner, Merrychef Oven Protector, heat proof gloves, protective rubber gloves,

non–abrasive nylon scrub pad, cleaning towel and cloths, eye protection and dust mask (optional)

COLD OVEN: CLEANING INSTRUCTIONS ( following cool down )

Wash all parts in warm soapy water. Wash off using a clean cloth and plenty of
clean, warm water. Dry using a fresh, clean cloth.

Remove top impinger plate

Remove the rack and lift

out bottom impinger plate

Undo fasteners

To remove grease fi lter

push down and lift out

3.

Wash off using a clean
cloth and plenty of clean
warm water to rinse top,
sides and back of oven.
Dry using a fresh clean
cloth or paper towel.
Wipe the outside of the
oven with a damp cloth.

1.

Wear protective rubber
gloves and protective
glasses carefully spray
Merrychef Oven Cleaner
onto the internal surfaces
of the oven except door
seals.
DO NOT spray directly
into the fan opening at
the rear of the oven

2.

For diffi cult areas leave
to soak for 10 minutes.
Leave the oven door
open during cleaning.
Use a non–abrasive
nylon scrub pad/sponge
to clean all internal sur-
faces and the inside of
the door.

4.

Replace clean oven
parts

Grease Filter*
Top plate*
Bottom plate*
Air fi lters x2

CAUTION: Wear protective rubber gloves when cleaning the oven

Remove air fi lters

both sides

Oven Parts and fi lters
& Oven Cavity

If the door seals are damaged, the oven
must be repaired by an approved Servicer.

DO NOT use the oven without clean
air fi lters and cavity grease fi lter in place

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32Z3539 Issue 4

APPENDIX 3: Cleaning procedure 2

18

For the oven to operate at peak effi ciency, the cavity, door and air fi lters and grease fi lter must
be kept clean.

A daily cleaning routine will ensure that you comply with the required hygiene standards and will help
to maintain and prolong the effi ciency of your oven.

Follow the SAFETY INSTRUCTIONS at the beginning of this manual.

Faults arising from neglect or
misuse including use without clean
fi lters in place are not covered
by the guarantee. Service visits
as a result of such faults will be
chargeable.

Hot surface

Hazard

WARNING: DO NOT use caustic cleaners on any part of the oven or oven
cavity as it will cause permanent damage to the Catalytic Convertors

DO NOT use the oven without clean air fi lters and cavity grease fi lter in place

1.

With the oven clean and
cold, spray Merrychef
Oven Protector onto the
sponge

START UP: OVEN COATING PROCEDURE ( clean, cold oven )

4.

Switch the oven ON
when the oven has
reached operating
temperature it will take
30 minutes to cure the
Oven Protector.

3.

Spread Oven Protector
lightly onto the internal
surface of the oven door

2.

Spread Oven Protector
lightly onto all internal
surfaces of the oven

Note: oven protector turns light brown when cured

• ALWAYS switch off at the electrical supply before
cleaning

• Complete COOL DOWN procedure and allow the
oven and accessories to cool before commencing
cleaning

• As required wipe out spillages with disposable
paper wipes

• NEVER use steel wool, knives or harsh abrasives
on any part of the oven

As with all electrical appliances, it is wise to have the
electrical connections inspected periodically.

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32Z3539 Issue 4

APPENDIX 4: Recommended spares lists UK/EC

Part No. Description Qty Unit

First

Aid Kit

Service

Kit

1-5

Ovens

5-50

Ovens

50-100
Ovens

Piece Qty for

600 Ovens

11H0364 HT DIODE PCB 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 W AY 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

30Z1340 FILTER 16A (Threaded) 2 EA 2 2 2 6 12 72

30Z1155 BLOCK TRANSFORMER B0012024 1 EA 1 1 3 6 36

30Z1349 MAGNETRON Toshiba 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 60HZ TRANS MULTI 208 220 240 2 EA 1 2 2 6 12 72

30Z1233 50HZ TRANS MULTI 208 220 240 2 EA 1 2 2 6 12 72

30Z1331 1.0uF 2500V (50HZ Model) 1 EA 1 2 2 6 12 72

30Z1242 1.1uF 2500V (50HZ Model) 1 EA 1 2 2 6 12 72

30Z1251 0.88uF 2500V (60Hz Model) 2 EA 2 4 2 6 12 72

30Z1294 MICROSWITCH W ITH 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 ASSEMBLY 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

30Z1319 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 INTERLOCK SPRING 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

SA273 CONTROL FASCIA ASSY 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

DV0305 DOOR SEAL (WIDE) 1 EA 1 1 2 6 12 72

DV0203 SEAL - CERAMIC COVER 2 EA 2 2 2 6 12 72

SA274 CONTROL FASCIA ASSY 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

DV0606 HEATER ELEMENT 220V 5 EA 3 5 5 15 30 180

DV0607 HEATER ELEMENT 240V 5 EA 3 5 5 15 30 180

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

SA225 MAINS LEAD ASSY (EU) 4-CORE 1 EA 1 1 2 4 24

SA226 MAINS LEAD ASSY (UK) 3-CORE 1 EA 1 1 2 4 24

SA231 LOGIC BOARD MAIN ASSY V2.0/2.5 1 EA 1 1 3 6 36

SA288 STIRRER MOTOR ASSY 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

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32Z3539 Issue 4

APPENDIX 5: LOGIC PCB Connection Points and key features.

Display
Connecter

Relay PCB 15 way
Connecter

Motor speed
controller

Membrane panel
connector

MenuKey

Socket

Connector

Door
Switch IP

Program

memory storage.

Chip may be

exchanged

with New PCB if

PCB replaced.

D7 Power LED

Indicates Logic PCB
is powered
See Troubleshooting
Guide

Door switch

Indicator

ON when door

closed

Temp Calibration

Remote data

point

Spare input
(not used)

Fibre Optic

Detector 1 to LHS

Fibre Optic

Detector 2 to RHS

Magnetron 2

Magnetron 1

Fibre Optic Magnetron
Detection

Solid State Relay

Heater regulation

circuit

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32Z3539 Issue 4

APPENDIX 5: Relay PCB Connection Points and key features.

AC input from

Aux Transformer

D20 LED
ON

when power is on

OFF

when Microwave is
operated.

Magentron

Overheat sensor

Inputs

Cavity

Temperature

Sensor

Input

Connector To

Logic PCB

D19 Heater ON

U1 Ambient air

temperature

sensor

Piezo sounder

output

Fuse

Not Used

Display

Fuse

D16 Magnetron

soft start

D15 Magnetron

active

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32Z3539 Issue 4

CODEKEY Reference ( See Table 1 for abbreviations description)

Version 3

Part No. 31Z7066 3.0LD 402s Large Display UK/EU (FO / EMD)
Part No. 31Z7068 3.0LD 402s Large Display French (FO / EMD)
Part No. 31Z7071 4.3LD 402s Large Display UK/EU (FO / SSR / EMD)
Part No. 31Z7072 4.3LD 402s Large Display French (FO / SSR / EMD)
Part No. 31Z7073 4.4LD 402s Large Display US/EU

(FO / SSR / EMD / NSS / NPM / NEPT / NEP)

For QSR restaurants

Version 2.5

Part No. 31Z7067 4.4SD 402s Small Display UK/EU (FO / EMD)

1.0 The 402s Control System

The control system of the 402s is based upon the following fundamentals:

Logic PCB:

Controls and monitors all aspects of the oven and stores all Firmware and Menu Data.

Firmware:

This is where all of the oven

operating instructions are
stored. It can be changed

by a CODEKEY

Menus:

This is where all of the

Information for menus is

stored. It can be changed

manually or by a MenuKey

LOGIC PCB

Relay PCB:

Driven by the Logic PCB the Relay PCB

controls all of the power around the oven.

Microswitches

Heater Elements

Magnetrons

Sensors

Convection Fan

Fibre Optic Expansion

Door Sensor

Solid State Relay

APPENDIX 6: Firmware revision guide.

As a result of on-going changes / upgrades to the 402s Oven, this Appendix has been produced
stating the following:

1.0 An overview of the control system for a 402s.

2.0 How to check your Firmware version

3.0 How to check your hardware fitted

4.0 CODEKEY firmware upgrade

5.0 MenuKey2 download

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32Z3539 Issue 4

2.1 Power up the oven and verify the Firmware version that is loaded into the oven.

2.0 How to check your Firmware Version:

OVEN INFORMATION

Oven On Time: 00028 Hours
Magnetron On Time: 00000 Hours
Door Operations: 00049
Software Version: 4.1LD
MenuKey Code: 002
MenuKey Checksum F076 PAUSE>>

Check the Software Version on the Oven Start Up screen and refer to Table 1 below

Firmware Verification: Table 1

Abbreviation

Code

Firmware Features
Supported

Firmware Version for 402s V3 ovens

2.8LD

or lower

3.0LD 4.0LD 4.1LD 4.2LD 4.3LD GM4.4LD

QSR

- Screen Saver

9 9 9 9 9 9 8

NSS No Screen Saver

8 8 8 8 8 8 9

- Edit Pre-Heat

9 9 9 9 9 9 8

NEPT Hidden Edit Pre-Heat

8 8 8 8 8 9 8

- Edit Profile

9 9 9 9 9 9 8

NEP Hidden Edit Profile

8 8 8 8 8 9 8

- Edit Programs

9 9 9 9 9 9 8

NPM Hidden Edit Programs

8 8 8 8 8 9 8

FO Magnetron Detect

8

9

*

9 9 9 9 9

EMD Extended Mag Detect

8 9 8 8 8 9 9

SSR Solid State Relay

8 8 9 9 9 9 9

Note: this Table excludes KFC France ovens.

Note: ALL ovens that are lower than 3.0LD Firmware should be up-lifted to version

3.0LD or higher depending on what hardware is fitted. (Refer to Table 2a & Table 2b)

CODEKEY Version 4.3LD or lower (GM ovens) CODEKEY Version 4.4LD (QSR ovens)

All ovens except ‘Quick Service Restaurants’

Subway and KFC

‘Quick Service Restaurants’ only including

Subway and KFC

Please also be aware of the store you are visiting as this would dictate what version of Firmware
they would require. See below for clarification.

*Only when Fibre Optic hardware is fitted.

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32Z3539 Issue 4

PCB Visual Check

Hardware fitted

against PCB visual

Supports

Oven

Upgrade

to V3

Allowable

Version /

Firmware

SSR

Mag

Detect

8 8 8

ONLY ON
V2 ovens

4.4SD

8





8

8





8

9





9

ON V2.5

ovens

4.4SD

or higher

ON V3

Ovens

3.0LD

or higher

No pin strip

Device
secured to
plate

Pin strip fitted but no optics board

Device
free
standing

3.0 How to check your hardware fitted:

3.1 Remove the oven lid to reveal the Logic PCB. See Table 2a below

TABLE 2B Hardware Upgrade

Hardware Upgrade

Technical Bulletin

Required

V2

oven

V2.5

oven V3oven

Adding Magnetron Detect

8

TB114 TB114

Adding Solid State Relay

8

TB122 TB122

Revision 1 Revision 2

TABLE 2A

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32Z3539 Issue 4

PCB Visual Check

Hardware fitted

against PCB visual

Supports

Oven

Upgrade

to V3

Allowable

Version /

Firmware

SSR

Mag

Detect

8




8

9




9

9




9

ON V2.5

ovens

4.4SD

ON V3

ovens

3.0LD

or higher

9 9 9

ONLY ON

V3

ovens

3.0LD

or higher

SSR lead

Fibre Optics Board + leads fitted

SSR would be
fitted if lead is

present on PCB

Optics
board fitted

Blue jumper
fitted

Revision 3

TABLE 2b: Hardware Upgrade

Hardware Upgrade

Technical Bulletin

Required

V2

oven

V2.5

oven V3oven

Adding Magnetron Detect

8

TB114 TB114

Adding Solid State Relay

8

TB122 TB122

TABLE 2A

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32Z3539 Issue 4

After I minute the Oven will boot-up immediately press the

PAUSE pad to hold the oven information screen.

OVEN INFORMATION

Oven On Time: 00028 Hours
Magnetron On Time: 00000 Hours
Door Operations: 00049
Software Version: 4.0LD
MenuKey Code: 002
MenuKey Checksum F076 PAUSE>>

PAUSE pad

Switch the oven ON to activate the CodeKey, the screen
will remain blank for approximately 1 minute before the

startup screen displays.

Warning:
During the next step the display will be blank for approximately 1 minute.

DO NOT REMOVE THE CODEKEY/ DO NOT TURN THE OVEN OFF

this will damage the logic board.

4.2

Lift cover to insert CodeKey into

Menukey receptacle.

Oven power switch

4.0 CODEKEY Firmware upgrade

Before commencing an oven Firmware upgrade ensure the oven is switched off

4.1 Insert the appropriate CODEKEY (see Matrix 01 on page 2) into the Menukey receptacle on the
control panel.

Procedure:

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32Z3539 Issue 4

4.3 To confirm a successful download check that the Software Version on
the oven and the CODEKEY fob Label are the same.

OVEN INFORMATION

Oven On Time: 00028 Hours
Magnetron On Time: 00000 Hours
Door Operations: 00049
Software Version: 4.3LD
MenuKey Code: 002
MenuKey Checksum F076 EXIT>>

Software Version

Software: 4.3LD
Date: 00/00/07
CS: 0x9C71

CODEKEY

Fob

Label

4.4 Press exit and remove and retain the CODEKEY.

5.0 MenuKey2 download

Before commencing a MenuKey download ensure the oven is switched OFF

1. Insert the appropriate MenuKey into the control panel
socket.

2. Switch the Oven ON
[DO NOT REMOVE the MenuKey as this will corrupt the
data on the key]

3. The display will show the following:

Procedure:

4. The display will show the start up sequence and the Oven will begin heating up.

5. Remove the MENUKEY

Verifying Programs

Copied successfully

MenuKey Copied

Successfully

MenuKey Detected

Please Wait

Copying Programs from

MenuKey to Oven

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32Z3539 Issue 4

APPENDIX 7: Electrical Installation Guide

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32Z3539 Issue 4

Whilst every effort has been made to ensure that the information contained in this manual is

accurate and complete, if you believe that an error has been made, or if you have any suggestions
for how the manual could be improved, please fill in and return this form. A review of any forms

returned will be made on a regular basis, and the manual will be updated if

required.

Name

Address

Page number on which error occurs (if applicable) -

Description of error

Suggestion for improvement to manual

Please return this form to:

MANUAL CORRECTIONS AND MODIFICATIONS

Service Dept.
Merrychef Limited,

Station Road West,
Ash Vale, Aldershot

Hampshire GU12 5XA
United Kingdom
Tel: [phone] Fax: [phone]
Internet address: http://www.merrychef.com
E-mail: [e-mail]