Merrychef RD401 Service Manual
Mealstream 401
SERVICE MANUAL
Part No. 32Z3311 Issue No. 8
For all Mealstream 401 models manufactured from January 2001
CAUTION MICROWAVE EMISSIONS
DO NOT BECOME EXPOSED TO EMISSIONS FROM THE MICROWAVE
GENERATOR OR PARTS CONDUCTING MICROWAVE ENERGY
Page 1 Mealstream 401Ovens 32Z3311 Issue 8
SERVICE MANUAL
Table of Contents
Safety Code...........................................................................3
Product Specifications...........................................................4
Principles of Operation ...................................... ....................5
Installation Instructions...................................................... 6-7
Error Codes and Diagnostics.................................................8
Main Features........................................................................9
Electronic Controls ..............................................................10
Manual Controls ..................................................................11
Power Output Testing to EN 60335-2-90 ............................12
Power Output Testing..........................................................13
Power Transformer Test......................................................13
High Voltage Capacitor Test................................................14
High Voltage Rectifier Test..................................................14
Magnetron Test ...................................................................14
Door Interlock Operation .....................................................15
Error Light Operation ..........................................................15
Casework.............................................................................16
Door Mechanism .................................................................17
Oven Cavity Components & Hot Air System.......................18
Oven Door Assembly...........................................................19
Magnetron & Door Interlock Components ...........................20
Magnetron & Door Interlock Components ...........................21
Major Electrical Components...............................................22
Input Wiring, Filters and Fuses............................................23
Input Wiring, Filters and Fuses............................................24
HT Components ..................................................................25
HT & Principal components: RMC1003__XX5/XX52 ..........26
Electronic Control Panel Assembly .....................................27
Manual Controls Panel Assembly............ ... .........................28
Membrane Panel Circuit............... .......................................29
Complete Spare Part Listing.......................................... 30-31
Circuit Diagrams............................................................ 32-34
Appendix 1 MenuKey Download Procedure........................35
Appendix 2 Cleaning Procedure..........................................36
Manual corrections and modifications .................................37
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 401Ovens 32Z3311 Issue 8
SAFETY CODE
This manual is designed to assist engineers who have been on a recognised product f amiliarisation
and training course run by Merrychef Limited. It has been prepared to offer technical guidance for the
Merrychef Mealstream 401 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.
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 on a Mealstream 401 oven, or before reconnecting the appliance to the
mains supply for testing, check all of the following points:
• All internal electrical connections are correct.
• All wiring insulation is correct and is not touching a sharp edge.
• All Earth connections are electrically and mechanically secure .
• All four 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 in the correct order.
• All fuse-holder safety covers are correctly fitted.
• 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 turntable is rotating correctly.
• The power output of the oven is correct (see pages 11 & 12 ).
• Microwave emission is below permissible limit - 5 mW/cm² (see BS EN 60335-2-90).
• Oven has correct 50mm air gap all round and 150mm above.
Air flow should not be restricted.
Page 3 Mealstream 401Ovens 32Z3311 Issue 8
Product specifications
ELECTRONIC CONTROLS
Model Number: RMC1003 + Voltage + Frequency + Current + Controls + Phase
For example: RMC100345XE52
Model Mealstream 401, 230-240V, 50Hz, 30A, Series 5 Controls, Twin Phase
Model prefix Voltage Frequency Current, Output, Heater Control
Type
RMC1003
2 = 220-230V a.c.
4 = 230-240V a.c
5 = 50 Hz
6 = 60 Hz
EE = 13A 700W 1500W
3000W
XE = 30A 700W 3000W
XX = 30A 1000W 3000W
5 =
Series 5
controls
MANUAL CONTROLS
Model Number: RMC1003 + Voltage + Frequency + Current
Model prefix Voltage Frequency Current
RMC1003
Power
2 = 220-230V a.c.
4 = 230-240V a.c.
See RATING PLATE on rear of oven
5 = 50 Hz
6 = 60 Hz
CD2 = 13amp
XD2 = 30amp
Requirements
Power Output Microwave 100%
Convection
Combination
700W (IEC 705)
3000W
700W + 1500W ( EE )
700W + 3000W ( XE )
1000W + 3000W ( XX5 )
Supply
Phase
2=
Twin
Phase
External
Dimensions
Height
Width
Depth
Internal
Dimensions
Height
Width
Depth
Turntable
Capacity
Weight Nett
Gross packed
Construction Cavity
Casework
Settings Microwave
Temperature
Timer
530 mm (Plus 150 mm minimum clearance above)
550 mm (Plus 50 mm minimum clearan ce each side)
575 mm (Plus 50 mm clearance behind)
315 mm
330 mm
330 mm
300 mm Diameter
34.3 litres
All models except XX5 45kg, XX5 55kg
All models except XX5 58kg, XX5 68kg
Vitreous Enamel Coated Steel
304 Stainless Steel
Anodised Aluminium Extrusions
100%,75%,50%,25%, Convection only
Off, 175°C, 200°C, 225°C, 250°C, 275°C
Up to 30 minutes
Up to 3 cooking stages of up to 30 minutes each
(Programmed)
Page 4 Mealstream 401Ovens 32Z3311 Issue 8
Principles of operation
Page 5 Mealstream 401Ovens 32Z3311 Issue 8
Installation instructions
Positioning the O ven
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 150mm above. Air intake temperature should not exceed 35°C.
Excessive temperature will lead to reduced operating duty cycle or premature ageing of
internal components.
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.
Page 6 Mealstream 401Ovens 32Z3311 Issue 8
Electrical installation:
WARNING: This appliance must be earthed.
Failure to do so may result in electric shock and death
WARNING
Establishments with standard ( Type ‘B’ ) circuit breakers are sensitive to ‘surges’ which occur
on switching on freezers, refrigerators and other catering equipment, including microwave
ovens. Because of this, we strongly recommend that a separate Type ‘C’ circuit breaker
( designed specifically for this type of equipment ) must be fitted. An individual, suitably rated
circuit breaker should be fitted for each oven installed.
Models RMC1003__EE5, RMC1003__CD2
The power outlet used must be individually fused. It
is essential that the socket is properly installed and
earthed. It should be fed from a circuit which is
suitable for high power electrical applia nces and it is
important that this circuit is not overloaded.
Where an approved and fitted moulded plug is
supplied we strongly recommend that this plug is
never removed.
However certain establishments may require a
different plug to be fitted. In this case, the wiring
instructions shown should be observed.
All models ( 30A ) must be connected to a separate electrical suppl y rated at
30 Amps by a qualified and approved electrician. A suitable 30 amp rated
isolating switch with a 3mm contact gap on both poles should be fitted for each
oven installed.
Diagram 1
Models RMC1003__XE5, RMC1003__XD, RMC1003__XX5
When supplied, single phase models are fitted with a
Blue 32Amp Plug approved to BS4343. Wiring cable
colours as shown in Diagram 1
The Circuit Breaker should be rated at 45A (TypeC).
TWIN PHASE
Models RMC1003__XE52, RMC1003__XX52
The Mealstream 401 oven Twin Phase models
should be connected as shown in Diagram 2.
The Circuit Breaker should be rated at 45A (TypeC).
Simplified loading Diagram
Diagram 2
Page 7 Mealstream 401Ovens 32Z3311 Issue 8
Error codes and diagnostics
The Mealstream EC401 will identify some of the most common problems by flashing an error
message code in the time display window.
Error Message
1
1
1 Oven Cavity overheating Check cavity sensor
Possible Cause Service
Door not fully shut
2
Possible electrical fault
No time has been set
Invalid time has been set
2
Invalid program has been set
3
Number pad failure
4
Memory Failure running a
5
Program
Oven not heating up
1
Possible Heater circuit fault
2
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 Magnetron overheating Check that magnetron cooling fan is
1
1 Oven control area is
MenuKey removed before th e
Magnetron has overheated
but has now recovered
2
Internal diagnostic fault
overheating
download is complete
or the process has been
interrupted
Allow oven to reach correct
Programmed temperature
working correctly
Check air filters
Check location and air inlet temperature
Note : this will lead to condition shown
below
Check that magnetron cooling fan and
turntable are working correctly
Check installation, air inlet temperature
and air filters
Check air filters.
Check axial fan
Check installation for hot air intake
Switch oven off and begin the MenuKey
download again
Page 8 Mealstream 401Ovens 32Z3311 Issue 8
Main features
a
b
p
c
f
h
n
rear view of Oven
i
b
m
a STEAM OUTLET
Allows steam and excess pressure to escape
from the oven cavity. It must be kept clear.
b AIR OUTLET
Warm air is vented here. It must be kept clear.
c TRAY HANDLE RESTS
There is one on each side of the oven for
convenient storage of the tray handle.
d BAFFLE PLATE
Forms the inside rear of the oven and covers the
hot air circulation fan. Removable for cleaning by
unscrewing the four wing nuts which hold it in
place. This must be cleaned on a regular basis,
and kept free of debris.
e RUNNERS
These 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.
g OVEN CAVITY
The oven cavity is mainly constructed form
vitreous enamelled steel panels. It must be kept
clean.
d
e
g
q
k
h TURNTABLE TRAY
The vitreous enamelled turntable tray fits onto the
turntable disc in the bottom of the oven cavity,
and rotates during cooking to ensure an even
distribution of microwave energy.
i AIR INLETS
Additional air inlets are situated along the lower
edge of the left-hand side panel, and must not be
obstructed.
j RATING PLATE
The rating plate is situated on the rear of the
oven, and states the Model, Serial Number,
Electrical Ratings and Manufacturers Tel no.
k 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.
l ON/OFF SWITCH
This is used to turn the oven On or Off.
IT DOES NOT ISOLATE INTERNAL WIRING
FROM THE ELECTRICAL SUPPLY.
m FEET
These feet are fitted to ensure adequate airflow
under the oven. They must not be removed.
n ELECTRICAL SUPPLY LEAD
p AIR FILTER
Main intake for cooling air for internal
components. Must be clear of obstruct ions.
q MenuKey
l
Page 9 Mealstream 401Ovens 32Z3311 Issue 8
Electronic controls: Mealstream EC401
a Stage LED's
b Service Indicator
c Air Filter Block Indicator
d Operator error indicator
e Program Display
f Temperature Set Pads
g Time / Program Number Pads
h Cancel/ Callback Pad
i Program Pad
j Convection Pad
k Microwave power Pads
l On/Off switch
m MenuKey socket
a
b
c
d
e
f
g
1
2
3
0
250225
21
4
5
738
P C
25%
75%0100%
200175
275
50%
i
h
j
k
6
9
l
m
Starbucks model
Page 10 Mealstream 401Ovens 32Z3311 Issue 8
Manual controls: Mealstream RD401
a Temperature Amber Neon
a
b
b Temperature Control
c Microwave Power Control
d Timer
e Start Pushbutton
f Cook cycle Red Neon
g Power Amber Neon
h On/Off switch
c
d
e
f
g
h
Page 11 Mealstream 401Ovens 32Z3311 Issue 8
Procedure A - Power Output Test
In accordance with BS EN 60335-2-90
This test is given in the BSI test standard f or microwave ovens. It is reproduced below - 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 1 kg to an accuracy of ± 1 g.
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 on the turntable. 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 calculated from the formula:
4.187 M
(T2-T1) + 0.55 MC (T2-T0)
W
P =
t
where
P is the microwave power output, in watts;
M
is the mass of the water, in grams;
W
M
is the mass of the container, in grams;
C
T
is the ambient temperature, in °C;
0
T
is the initial temperature of the water, in °C;
1
T
is the final temperature of the water, in °C;
2
t is the heating time in seconds, excluding the magnetron filament heat-up time.
Page 12 Mealstream 401Ovens 32Z3311 Issue 8
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