AEG MCD2660E Service Manual download pdf (Page 27)

SOI 03.06 FV 27/38 599 36 78-45

SERVICING

1. Precautions for Handling Electronic

Components

This unit uses CMOS LSI in the integral part of the

circuits. When handling these parts, the following

precautions should be strictly followed. CMOS LSI

have extremely high impedance at its input and

output terminals. For this reason, it is easily

influenced by the surrounding high voltage power

source, static electricity charge in clothes,

etc. and sometimes it is not fully protected by the

built-in protection circuit.

In order to protect CMOS LSI.

1) When storing and transporting, thoroughly wrap

them in aluminium foil. Also wrap all PW boards

containing them in aluminium foil.

2) When soldering, ground the technician as

shown in the figure and use grounded soldering

iron and work table.

2. Servicing of Touch Control Panel

We describe the procedures to permit servicing

of the touch control panel of the microwave

oven and the precautions you must take when

doing so. To perform the servicing, power to the

touch control panel is available either from the

power line of the oven itself or from an external

power source.

(1) Servicing the touch control panel with

power line of the oven:

CAUTION:

THE HIGH VOLTAGE TRANSFORMER OF

THE MICROWAVE OVEN IS STILL LIVE

DURING SERVICING AND PRESENTS A

HAZARD.

Therefore, before checking the performance of

the touch control panel,

1) Disconnect the power supply cord, and then

remove outer case.

2) Open the door and block it open.

3) Discharge high voltage capacitor.

4) Disconnect the leads to the primary of the

power transformer.

5) Ensure that these leads remain isolated from

other components and oven chassis by using

insulation tape.

6) After that procedure, re-connect the power

supply cord.

After checking the performance of the touch

control panel,

1) Disconnect the power supply cord.

2) Open the door and block it open.

3) Re-connect the leads to the primary of the

power transformer.

4) Re-install the outer case (cabinet).

5) Re-connect the power supply cord after the

outer case is installed.

6) Run the oven and check all functions.

A. On some models, the power supply cord

between the touch control panel and the oven

itself is so short that the two can’t be separated.

For those models, check and repair all the

controls (sensor-related ones included) of

the touch control panel while keeping it

connected to the oven.

B. On some models, the power supply cord

between the touch control panel and the oven is

long enough that they may be separated from

each other. For those models, it is possible to

check and repair the controls of the touch

control panel while keeping it apart from the

oven; in this case you must short both ends of

the door sensing switch (on PWB) of the touch

control panel with a jumper, which activates an

operational state that is equivalent to the oven

door being closed.

(2) Servicing the touch control panel with

power supply from an external power

source:

Disconnect the touch control panel completely

from the oven, and short both ends of the door

sensing switch (SW3: STOP SWITC on PWB

CNB connector 1 and 2) of the touch control

panel, which activates an operational state that

is equivalent to the oven door being closed.

Connect an external power source to the power

input terminal of the touch control panel, then it

is possible to check and repair the controls of

the touch control panel.

3. Servicing Tools

Tools required to service the touch control panel

assembly.

1) Soldering iron: 30W

(It is recommended to use a soldering iron with

a grounding terminal.)

2) Others: Hand tools

4. Other Precautions

1) Before turning on the power source of the

control unit, remove the aluminium foil applied

for preventing static electricity.

2) Connect the connectors of the key unit to the

control unit being sure that the lead wires are

not twisted.

3) After aluminium foil is removed, be careful that

abnormal voltage due to static electricity etc. is

not applied to the input or output terminals.

4) Attach connectors, electrolytic capacitors, etc.

to PWB, making sure that all connections are

tight.

5) Be sure to use specified components where

high precision is required.

approx. 1 M ohm

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AEG MCD2660E Service Manual Page 27

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