Merrychef EC501, EC502 Service Manual

Merrychef

Mealstream 500

SERVICE MANUAL

Part No. 32Z3387 Issue No.3

For all Mealstream 501, 502 & 503 models manufactured

from January 2001 & Tim Hortons Models

CAUTION MICROWAVE EMISSIONS

DO NOT BECOME EXPOSED TO EMISSIONS FROM THE MICROWAVE

GENERATOR OR PARTS CONDUCTING MICROWAVE ENERGY

SERVICE MANUAL

Page 1 Mealstream Ovens 32Z3387 Issue 3

Table of Contents

Safety Code...........................................................................3

Product Specifications...........................................................4

Installation Instructions..........................................................5

Error Codes and Diagnostics.................................................6

Main Features........................................................................7

Electronic Controls ................................................................8

Manual Controls ....................................................................9

Power Output Testing to EN 60335-2-90 ............................10

Power Output Testing..........................................................11

Power Transformer Test......................................................11

High Voltage Capacitor Test................................................12

High Voltage Rectifier Test............... ... ... .............................12

Magnetron Test ...................................................................12

Principal components LHS..................................................13

Principal components RHS..................................................14

Principal components Top...................................................15

Principal components Cavity Roof and Door.......................16

Principal components Cavity...............................................17

Principal components ( not shown in main views ) .............18

Input wiring..........................................................................19

Interlock Operation..............................................................20

Electronic Control Panel Assembly .....................................21

Manual Controls Panel Assembly........................................22

Membrane Panel Circuit......................................................23

Complete Spare Part Listing.......................................... 24-25

Electrical Diagrams ....................................................... 26-27

Appendix 1: MenuKey Download Procedure..................... ..28

Appendix 2: Cleaning procedure...... ............................. 29-30

Appendix 3: PCB Connection Points............................. 31-33

Appendix 4: Transformer upgrade..................... ... ... ............34

Appendix 5 Hot air motor replacement......................... 35-39

Appendix 6: Temperature sensor replacement ...................40

Appendix 7: Fuse change FLM020 Type....................... 41-42

Appendix 8: Tim Hortons .............................................. 44-47

Appendix 9: Door interlock set-up procedure ................ 48-52

Manual corrections and modifications.................................53

Merrychef Limited, Station Road West, Ash Vale, Aldershot Hampshire GU12 5XA United Kingdom Tel: +44 (0)1252 371000 Fax: +44 (0)1252 371007 Internet address: http://www.merrychef.com E-mail: sales@merrychef.com or service@merrychef.com

Page 2 Mealstream Ovens 32Z3387 Issue 3

SAFETY CODE

This manual is designed to assist engineers who have been on a recognised product familiarisation and training course run by Merrychef Limited. It has been prepared to offer technical guidance f or the Merrychef Mealstream 501 range of Combination Microwave 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 leakage. 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

Before removing the rear cover from the oven, ensure you do the following:

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

• 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 on a Mealstream oven, or before reconnecting the appliance to the mains supply for testing, check all of the following points:

• All internal electrical connections are correct (see wiring diagram Pages 26-27).

• All wiring insulation is correct and is not touching a sharp edge.

• All Earth 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 three of the door interlock switches in the correct order.

• The temperature sensor is correctly connected to the Power PCB.

Before finishing the service call, recheck the following points:

• All of the electronics are functioning correctly, and all of the touch pads are working.

• The power output of the oven is correct.

• Microwave emission is below permissible limit - 5 mW/cm² (see BS EN 60335-2-90).

• Oven has correct 50mm air gap all round and 50mm above.

Air flow should not be restricted.

• Clean air filters are in place.

Page 3 Mealstream Ovens 32Z3387 Issue 3

Product specifications:

Model Number: CTMx v f c p MK C

Example CTM524505MK

Mealstream EC501, High speed fan 230-240V, 50Hz, Series 5 electronic controls & MenuKey

CTMx Fan Speed

CTM3 =

Low speed CTM5 = High speed

Power Requirements

Power Output: CTM3

CTM5

External Dimensions

Internal Dimensions

v Voltage

22 = 220-230V EU 24 = 230-240V UK

Refer to rating Plate

Microwave 100% Convection Combination Convection Combination

Height Width Depth

Height Width Depth Capacity

f Frequency c Control Type p Phase

50 = 50 Hz 60 = 60 Hz

5 = Electronic

CD2 = Rotary Dial

Controls

2 = 2 phase 1 = 1 phase

Omitted

1425W (IEC 705) 2500W 1425W + 2500W 3000W 1425W + 3000W

640mm (Plus 50mm minimum cleara nc e ab ove) 710mm (Plus 50mm minimum clearance each side) 630mm (Plus 50mm clearance behind)

260mm 490mm 360mm

45.86 litres (1.62 ft³)

MK MenuKey

MK =

MenuKey fitted

C Catalytic Converter

EC503 Catalytic Converter

Weight Nett

Gross packed

Construction Cavity

Casework

Settings Microwave

Temperature Timer

90kg 106kg

304 Stainless Steel

100%,75%,50%,25%, Convection only Off, 150°C, 175°C, 200°C, 225°C, 250°C Up to 30 minutes Up to 3 cooking stages of up to 30 minutes each Programmed (Series 5)

Page 4 Mealstream Ovens 32Z3387 Issue 3

Installation instructions:

Installation Instructions for Mealstream 500 series Combination Ovens

Power Supply Requirements

The Mealstream 500 series oven should be connected to a suitable electricity supply, which can cope with the switching-on surge that occurs with certain types of catering equipment, such as 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" circuit breaker, rated at: 30 Amp for Mealstream 500 Series (all models) If the oven is hard-wired to the supply, a double-pole isolator switch with a contact gap of at

least 3mm should be fitted and positioned close to the oven to allow the oven to be moved for servicing.

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 50mm clearance at the sides and rear of the oven, and at least 50mm above. Air intake temperature should not exceed 35°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. NEVER Stack machines on top of each other - always use a double stand.

ALWAYS Place containers in the cavity carefully - impact damage may chip the

vitreous enamel coating on the runners and baffle plate.

50mm 50mm

50mm

350mm

Page 5 Mealstream Ovens 32Z3387 Issue 3

Error codes and diagnostics

Models with electronic controls identify some of the most common problems by flashing an error message code in the time display window.

Error Message

1 Oven Cavity overheating Check cavity sensor

Possible Cause Service

Door not fully shut

Possible electrical fault

No time has been set Invalid time has been set

Invalid program has been set

Number pad failure

Memory Failure running a

Program Oven not heating up

Possible Heater circuit fault

Close door fully Check Microswitch Door Circuit

Check Microswitch Connection to PCB Check Ribbon Cable Check Relay PCB & Logic PCB

Set a time Set a valid time Use call-back to check program (MenuKey: no key downloaded) Membrane key short circuit Re-Program Pad, if fault repeats replace Logic PCB

Check heater fuse Confirm operation of heater, overheat

stat and heater circuit

Confirm heater relay is operating

1 Oven is not at correct

temperature to start program Operator Error !!

1 Oven control area is

overheating.

MenuKey removed before the

download is complete or the process has been interrupted.

Allow oven to reach correct Programmed temperature

Check air filters Check axial fan Check installation for hot air intake

Switch oven off and begin the MenuKey download again.

Page 6 Mealstream Ovens 32Z3387 Issue 3

Main features:

back panel

a On/Off SWITCH

This is used to turn the oven On or Off.

IT DOES NOT IS OLATE INTERNAL WIRING FROM THE MAINS SUPPLY.

b HOT AIR VENTS

Allows steam and excess pressure to escape

from the oven cavity. It must be kept clear.

c OVEN CAVITY

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

d BAFFLE PLATE

EC501 Models: The convection fan draws air over the heating element into the cavity ove r the edges of the rear baffle plate producing perfect heat distribution for combination cooking. The metal grill covering the fan must be kept clean and free of debris. 502 & 503 Models: The convection fan, which is located behind the cavity filter pulls air in through the catalytic converter which removes the majority of the smoke from the air flow.

e RUNNERS

These are mounted on each side of the oven cavity to support the rectangular racks or oven trays and are for use in Convection mode only.

f HOT AIR FAN

Situated behind the baffle plate, and circulates the hot air through the baffle plate, over the heating element, and around the edge of the baffle plate back into the cavity. CTM3_ Low speed Fan CTM5_ High Speed Fan

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.

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. It is important that the choke plate and the slots are free from debris.

i DOOR SEAL j MAINS LEAD

k AIR FILTERS

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

l MenuKey

m STEAM OUTLET

Page 7 Mealstream Ovens 32Z3387 Issue 3

Electronic controls:

a Stage LED's b Program & Time Display c Service Indicator d Air Filter Block Indicator e Convection Pad

f Power Pads g Time / Program Number Pads h Temperature Set Pads

i Cancel / Callback Pad

j Program Pad k MenuKey socket

Page 8 Mealstream Ovens 32Z3387 Issue 3

Manual controls:

merrychef

c d

POWER %TEMP °C

TIME

START

Mealstream CD

a Power Neon ( Amber ) b Temperature Control c Power Control d Timer e Start Push button

f Cook cycle Neon ( Red )

g Heater Neon ( Amber )

Page 9 Mealstream Ovens 32Z3387 Issue 3

Procedure A - Power Output Test in accordance with BS EN 60335-2-90 Annex AA

This test is given in the BSI test standard for microwave ovens. It is reproduced belo w - not so that you can follow it, but to show you why it is impractical in normal conditions. A simplified procedure, which gives a good approximation to the BSI power output, is given in Procedure B which follows.

Note: This test can only be carried out on a COLD oven. If the oven has been operating, even for only a few seconds, the power given will be lower than the oven rating. This test must also be carried out at a stable voltage - the voltage in most kitchens varies considerably even within the period of the test. If the oven has been operating, go to Procedure B.

You will need:

A thermometer capable of reading to ±0.1°C. A cylindrical borosilicate glass container, 190 mm diameter, with a wall thickness of

3 mm or less.

A calculator. A set of scales capable of reading 1kg to an accuracy of ± 1g. A glass or plastic stirrer. A jug capable of holding over 1 litre of water. Drinkable water which is at a temperature of 10°C ± 1°C. A “Variac” or similar variable transformer capable of supplying the oven to ensure a

stable voltage.

WARNING: The Borosilicate Glass container has thin walls and is therefore fragile

- take care not to break it during use.

Method A cylindrical container of borosilicate glass is used for the test. It has a maximum thickness of 3mm, an external diameter of approximately 190mm and a height of approximately 90mm. The mass of the container is determined.

At the start of the test, the oven and the empty container are at ambient temperature. Potable water having an initial temperature of 10°C ± 1°C is used for the test. The temperature of the water is measured immediately before it is poured into the container.

A quantity of 1000g ± 5g of water is added to the container and its actual mass obtained. The container is then immediately placed in the middle of the oven base. The appliance is supplied at rated voltage and operated at the maximum power setting. The time for the water temperature to attain 20°C ± 2°C is measured. The oven is then switched off and the final water temperature is measured within 60seconds.

NOTES:

1 The water is stirred before its temperature is measured. 2 Stirring and measuring devices are to have a low heat capacity.

The microwave power output is calculat e d from the formula:

4.187 M

(T2-T1) + 0.55 MC (T2-T0)

P = t where

P is the microwave power output, in watts; M

is the mass of the water, in grams;

is the mass of the container, in grams;

is the ambient temperature, in °C;

is the initial temperature of the water, in °C;

is the final temperature of the water, in °C;

t is the heating time in seconds, excluding the magnetron filament heat-up time.

Page 10 Mealstream Ovens 32Z3387 Issue 3

Procedure B - Simplified Power Output Test

You will need:

A thermometer capable of reading to ±0.1°C. A Polypropylene tray approximately 200 mm x 200 mm. A measuring jug. A calculator. Water which is at a temperature of 10°C ± 2°C.

1 Measure 1 litre of cold water into the tray using the measuring jug. 2 Measure the water temperature, and record it as T[s]. 3 Place the tray in the oven and close the door. 4 Turn the oven on. 5 Set the timer to 1:02. ( For Manual controls use a stopwatch set to 1 minute 2 seconds ) 6 Press the “100%” power pad. 7 When the oven bleeps, open the door and remove the tray. 8 Stir the water thoroughly, and measure its temperature. Record this as T[e].

Calculation:

1 T[r] = T[e] - T[s]. 2 Power = 70 x T[r]. Power is in Watts.

The power given by the above test should be within ±10% of the rated power.

For Tim Hortons see APPENDIX 8

Procedure C - Power Transformer 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.

WARNING: High voltages and large currents are present at the secondary winding and filament

winding of the Power Transformer. 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 n ot cooking, the Power Transformer has High Voltages present

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

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 continuity of the windings. Results should be as follows:

a Mains winding between tags b High Voltage winding c Filament winding

between terminals

Approx. 1.3 Ω Approx. 82 Ω Less than 1 Ω

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.

Pass if over 10 MΩ Pass if over 10 MΩ

Page 11 Mealstream Ovens 32Z3387 Issue 3

Procedure D - 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 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.

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 &

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

Procedure E - 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 Rectifier. 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 Rectifier 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 High Voltage

Rectifier.

4. Using the Megger, test for continuity in both

directions. Compare results with the table.

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

Open Circuit both ways Conducts one way only Short Circuit both ways Conducts one way, leaks the other

FAIL

PASS

FAIL FAIL

Procedure F - 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.

Page 12 Mealstream Ovens 32Z3387 Issue 3

Principle components:

Left side

4A 4

7 8

No Description EC 501/2/3 RD 501

1 Fuse holder 30Z0231 30Z0231 1A Fuse 10 amp 30Z0217 30Z0217 2 Fuse holder 30Z0231 30Z0231 2A Fuse 10 amp 30Z0217 30Z0217 3 Fuse holder 30Z0231 30Z0231 3A Fuse 1 amp 30Z0957 30Z0957 4 Fuse holder 30amp ( FLM Series )B 30Z1178 30Z1178 4A Fuse 20 amp Littlefuse FLM020B 30Z1177 30Z1177 6 Mains terminal block 31Z0149 31Z0149 7 Filter ( Heater circuit ) 30Z0997 30Z0997 8 Filter ( Microwave circuit ) 30Z0997 30Z0997 9 Door spring short 520000 520000

9 Door spring long 40C1141 40C1141 10 Door arm stop assembly 11C0279 11C0279 11 Microswitch ( Primary ) 30Z0240 30Z0240 12 Door hinge assembly ( LH )A 11C0167 11C0167 13 Door arm assembly 11C0300 11C0300 14 Microswitch ( Monitor ) 30Z0240 30Z0240

Note A: see page 17 for parts Note B: see appendix for models before March 2004

Page 13 Mealstream Ovens 32Z3387 Issue 3

Principle components:

Right side

No Description EC 501/2/3 RD 501

9 Door spring short

9 Door spring long 10 Door arm stop assembly 13 Door arm assembly 16 Door hinge assembly ( RH )A 17 Microswitch ( Secondary ) 20 Steam pipe 21 Steam vent guard 22 Temperature sensorC

Note A: see page 17 for parts

Note C: see appendix for models before March 2004

9 10

520000 520000

40C1141 40C1141

11C0279 11C0279 11C0300 11C0300 11C0166 11C0166 30Z0240 30Z0240

790046 790046 790061 790061

50E123 50E123

Page 14 Mealstream Ovens 32Z3387 Issue 3

Principle components:

Top view

60 61

No Description EC 501/2/3 RD 501

23 Magnetron 30Z0264 30Z0264 24 Resist or Gold 470 R 30Z0283 30Z0283 25 HT diode 11C0266 11C0266 26 Capacit or 1. 1µF 30Z1077 30Z1077 27 Trans f o rmer 220 V 50Hz 30Z0083 30Z0083 27 Trans f o rmer 240 V 50Hz 30Z1018 30Z1018 28 Twin blower motor 310110 310110 60 25mm OD Flexible conduit 314402 314402 61 20mm OD Flexible conduit 314401 314401 62 Capacitor c lip 31Z0175 31Z0175

Page 15 Mealstream Ovens 32Z3387 Issue 3

Principle components:

Door & cavity roof

67a

Note: for Tim Hortons see Appendix 8

No Description EC 501/2/3 RD 501

67 Stirrer glass & long seals 40C0954 40C0954

67a Stirrer glass short side seal 790052 790052

71 Door seal kit 11C0292 11C0292

Air Filters

72 Door choke 790007 790007

No Description EC 501/2/3 RD 501

81 Air fi lt er panel (remov abl e) 40C0868 40C0868

Page 16 Mealstream Ovens 32Z3387 Issue 3

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