Merrychef HD1025, HD1925 Service Manual

Merrychef

Microcook HD

Microcook TA

S E R V I C E M A N U A L

Part No. 32Z3385 Issue No. 5

For all Microcook HD & TA models manufactured from January 2001

CAUTION MICROWAVE EMISSIONS

S E R V I C E M A N U A L

DO NOT BECOME EXPOSED TO EMISSIONS FROM THE MICROWAVE GENERATOR OR PARTS CONDUCTING MICROWAVE ENERGY

Microcook HD Ovens 32Z3385 Issue 5

Page 1

Table of Contents
Safety Code...........................................................................	3
Microcook HD Specification Sheet ........................................	4
Microcook TA Specification Sheet…………….............. …….5
Installation Instructions ..........................................................	6
Error Codes & Diagnostics ....................................................	7
Power Output Test Procedure A............................................	8
Simplified Power Output Test B.............................................	9
Transformer / Capacitor Test Procedure C & D ..................	10
Rectifier Test Procedure E ..................................................	11
Door Interlock Operation .....................................................	11
Oven Main Features ............................................................	12
Rear Cover Assembly.........................................................	13
Door Assembly 500mm Die Cast ........................................	14
Door Assembly 650mm .......................................................	15
Control Panel Assembly ......................................................	16
Component Layout HD1025................................................	17
Component Layout HD1425 / 1725.....................................	18
Component Layout HD1925................................................	19
Component Layout HD2025…………………..... …………...20
Component Layout TA 1725, TA 1925................................	21
Cavity Components .............................................................	22
Door Mechanism Right side ................................................	23
Door Mechanism Left side...................................................	24
Hot Air Motor Assembly.......................................................	25
Microcook TA Fan Control PCB and Heater Setup ......	26-27
Input Wiring Details .............................................................	28
Part Number Identification List ......................................	29-30
Wiring Diagrams ............................................................	31-35
Appendix 1 KFC components .............................................	36
Appendix 2 Capacitors and Magnetrons .............................	37
Appendix 3 Cleaning ..........................................................	38
Appendix 4 MenuKey download ..........................................	39
Appendix 5 Fitting 20A Anti surge fuses........................	40-41
Appendix 6 Logic board and Magnetron Failure Detect ......	42
Manual Corrections and Modifications ................................	43

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]

Microcook HD Ovens 32Z3385 Issue 5

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SAFETY CODE

This manual is designed to assist engineers who have successfully completed a Merrychef Service training course. It has been prepared to offer technical guidance for the Merrychef Microcook HD and Microcook TA Commercial 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

The following must be carried out prior to removing the rear cover from the oven :

•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 mains isolator switch.

Upon completion of a service on an Microcook 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 three door safety interlocks are secure and mechanically sound.

•The door operation is smooth.

•The door activates all three of the door interlock switches in the correct order.

•All fuse-holder safety covers are correctly fitted.

Before finishing the service call, recheck the following points:

•The oven is electrically safe

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

•The power output of the oven is correct (see pages (8 & 9).

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

•Oven has correct 50mm air gap all round. Air flow should not be restricted.

Microcook HD Ovens 32Z3385 Issue 5

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Product specifications:

Microcook HD Series

Microcook HD1025, HD1425, HD1725, HD1925 & HD2025

Model Number: Model prefix + Type + Voltage + Frequency + UK/Export + Customer

For example: 1925C450UK

Model 1925, Microcook, 230-240V, 50Hz, UK model

Model

Type

Voltage

Frequency

UK/Export

Customer

prefix

1025

C= Cook

2= 220-230V a.c.

50

= 50 Hz

UK = UK model

KFC

1425

V=Vend

4= 230-240V a.c

60

= 60 Hz

EX = Export model

FP = Feastpoint

1725

BL = Bourne Leisure

1925

2025

Power

Model HD1025

1.75kW

Requirements

Model HD1425

2.60kW

Model HD1725

2.88kW

Model HD1925

3.12kW

Model HD2025

Power Output

Microwave 100%

1025W (IEC 705)

1425W (IEC 705)

1725W (IEC 705)

1925W (IEC 705)

External

Height

475mm (Plus 50mm minimum clearance above)

Dimensions

Width

496mm (Plus 50mm minimum clearance each side)

Depth

499mm (Plus 50mm clearance behind)

Internal

Height

200mm

Dimensions

Width

390mm

Depth

365mm

Capacity

28.5 Litres ( 1.01ft³)

Weight

Nett

42.5kg

Gross packed

45kg

Construction

Cavity

304 Stainless Steel

Casework

304 Stainless Steel

Coated Aluminium extrusions

Settings

Microwave

100%,50%, Defrost

Timer

Up to 10 minutes

Up to 3 cooking stages of up to 10 minutes each Program

Microcook HD Ovens 32Z3385 Issue 5

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Product specifications:

Microcook TA Series

Microcook TA1725 & TA1925

Model Number: Model prefix + Turbo + Voltage + Frequency + Type

Model		Turbo				Voltage		Frequency	Type
prefix
TA1725	MT = Manual Turbo				2= 220-230V a.c.			5 = 50 Hz	UK = UK model
TA1925	VT = Vend Turbo				4= 230-240V a.c			6 = 60 Hz	EX = Export model
									EE = Twin 13amp Lead
									EX = Single 30 amp Lead
Power			TA1725				3.12kW
Requirements			TA1925				5.50kW ( 3.12kW + 2.38kW )
Power Output			TA1725
			Microwave 100%				1725W (IEC 705)
			Hot Air				1400W
			Combination				865W Microwave plus 1400W Hot Air
			TA1925
			Microwave 100%				1925W (IEC 705)
			Hot Air				2000W
			Combination				1925W Microwave plus 2000W Hot Air
Power supply lead			TA1725				13 Amp plug BS 1363A ( UK only )
			TA1925				2 x 13 Amp plug BS 1363A ( UK only )
							or 1 x 30Amp cable with plug BS4343 ( UK only )
External			Height				475mm (Plus 50 mm minimum clearance above)
Dimensions			Width				496mm (Plus 50 mm minimum clearance each side)
			Depth				499mm (Plus 50 mm clearance behind)
Internal			Height				200mm
Dimensions			Width				390mm
			Depth				365mm
			Capacity				28.5 Litres ( 1.01ft³)
Weight			Nett				42.5kg
			Gross packed				45kg
Construction			Cavity				304 Stainless Steel
			Casework				304 Stainless Steel
							Coated Aluminium extrusions
Settings			Microwave				TA1725 100%,50%, turbo
							TA1925 100%, heat only, turbo
			Timer				Up to 9 minutes 59 seconds
							Up to 3 Programmed cooking stages of up to 9 minutes
							59 seconds each ( total 29 minutes 57 seconds)

Microcook HD Ovens 32Z3385 Issue 5

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Installation instructions

Power Supply Requirements

The Microcook HD & Microcook TA ovens 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 16A.

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 all around the oven. Air intake temperature should not exceed 35°C - excessive temperature can 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 Place containers in the cavity carefully - impact damage may chip the oven shelf.

A – HD2025 Model

B – HD1025 Model

Note:

The 840mm clearance at the front allows the complete removal of the door for cleaning

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Error codes and diagnostics

The Microcook will identify some of the most common problems by flashing an error message code in the time display window.

These are the error messages, and suggestions for repairing them:

All HD & TA Models

Display		Fault (frequency)	Recommended Action
	1	Door not fully closed	Check the door is fully closed.
		(permanent)	Check the door down LED is illuminated on the control
			board.
			Check ribbon connector condition and fit.
	2	Magnetron	Ensure the oven has been
		overheating	installed correctly.
		(Intermittent)	Check the magnetron cooling fan is operating and free
			from obstruction.
	1	Membrane panel	Replace membrane panel.
		failure
		(permanent)
	2	Membrane panel	Replace membrane panel.
		failure
		(Intermittent)
	3	Incorrect time set.	Check correct time is set
		( Intermittent )	ie : 1.00 minute Not 60 seconds

KFC HD Models (with Fibre Optic Magnetron Detection)

	Display				Fault (frequency)		Recommended Action
					LH Magnetron Failure		Check Power supply
							Replace magnetron(s)
					RH Magnetron Failure
					Both magnetrons have
					failed
	TA Models
	Display				Fault (frequency)		Recommended Action
			1		Microcook TA		Check full / half wave LED
					Convected hot air		on control board
					failure (permanent)
			2		Intermittent		Check heating element

Microcook HD Ovens 32Z3385 Issue 5

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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 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, 190mm diameter, with a wall thickness of 3mm 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 1litre 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 shelf which is in its lowest normal position. 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 60’seconds.

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:

	P =	4.187 MW (T2-T1) + 0.55 MC (T2-T0)
where		t
P	is the microwave power output, in watts;
MW	is the mass of the water, in grams;
MC	is the mass of the container, in grams;
T0	is the ambient temperature, in °C;
T1	is the initial temperature of the water, in °C;
T2	is the final temperature of the water, in °C;
t	is the heating time in seconds, excluding the magnetron filament heat-up time.
Microcook HD Ovens 32Z3385 Issue 5				Page 8

Procedure B - Simplified Power Output Test

You will need:

A thermometer capable of reading to ±0.1°C.

A Polypropylene tray approximately 200mm x 200mm.

A measuring jug.

A calculator.

Water which is at a temperature of 10°C ± 2°C.

1Measure 1 litre of cold water into the tray using the measuring jug.

2Measure the water temperature, and record it as T[s].

3Place the tray on the turntable in the oven and close the door.

4Turn the oven on.

5Set the timer to 1:02.

6Press the “100%” power pad.

7When the oven bleeps, open the door and remove the tray.

8Stir the water thoroughly, and measure its temperature. Record this as T[e].

Calculation:

1T[r] = T[e] - T[s]

2Power = 70 x T[r]. Power is in Watts

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

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 not cooking, the Power Transformer has High Voltages present because of the Soft Start circuit. Isolate the oven before testing.

2Ensure that the High Voltage Capacitor is discharged before commencing work.

3Remove all connections from the Power Transformer.

4Using a D.M.M., check the continuity of the windings. Results should be as follows:

				c
a	Mains winding between tags	Approx. 1.3 Ω				b
b	High Voltage winding	Approx. 82 Ω
c	Filament winding	Less than 1 Ω
	between terminals

5 Using a Megger, test the insulation resistance between:

Primary winding and chassis	Pass if over 10 MΩ		a
Filament winding and chassis	Pass if over 10 MΩ
One end of the High Voltage winding is connected to the
chassis, so this is not tested.
Microcook HD Ovens 32Z3385 Issue 5			Page 9

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 &
		compare results with table.
		Between Terminals		Pass if approximately 10 MΩ
		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		Pass if over 100 MΩ

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

WARNING: Even when the oven is not cooking, the High Voltage Rectifier 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 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

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.
Microcook HD Ovens 32Z3385 Issue 5	Page 10

Door interlock operation

The door on the Microcook oven is monitored by three microswitches used in the conventional “Primary, Secondary and Monitor” switch arrangement shown below.

L

Primary

Secondary

Power

Power In

Out

Monitor

Door Interlock

N

Arrangement

The switches operate as follows:

1.Monitor Switch [TopRight]. As the door is closed, the monitor switch is opened.

2.Primary Interlock Switch [ Bottom Left ]. The Primary switch is then closed.

3.Secondary Interlock Switch [ Bottom Right ]. The Secondary Switch then closes.

When the door is opened, the switches operate in the reverse order.

Microcook HD Ovens 32Z3385 Issue 5

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Main features

a

c

d

e

f

g

microcook

C

e

turboaire ll

Vend model (KFC)

Description of Features

a.Program Pad

b.On/Off Switch

c.Program Display

d.Program Selection / Time Set Pads

e.Power Selection Pads

HD models:100%, 50% & de-frost TA models:100%, hot-air & turbo

f.Time Display

g.Cancel / Callback Pad

h.Door

C

b

h

Microcook HD Ovens 32Z3385 Issue 5

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Rear cover assembly

HD1025 only Rear View

5

1

All other models

Outer View

Inner View

2

1

5

3

7

6

No	Description	HD1025	HD1425	HD1725	HD1925	HD2025	TA
1	Rear Cover	40M0883	11M0269	11M0269	11M0269	11M0270	11M0269
2	Push Fit Feet	—–	31Z1187	31Z1187	31Z1187	31Z1187	31Z1187
3	Air filter	—–	31Z1104	31Z1104	31Z1104	31Z1104	31Z1104
4a	Screw M5x16	31Z3022	31Z3022	31Z3022	31Z3022	31Z3022	31Z3022
4b	M5 Star Washer	31Z5012	31Z5012	31Z5012	31Z5012	31Z5012	31Z5012
5	Installation Label	31Z2071	31Z2071	31Z2071	31Z2071	31Z2071	31Z2071
6	Self Adhesive Foam Tape	—–	31Z0158	31Z0158	31Z0158	31Z0158	31Z0158
7	Service History Label	31Z2056	31Z2056	31Z2056	31Z2056	31Z2056	31Z2056

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