Philips MCM-285 Service Manual

Micro Hi-Fi System

MCM285

-/55/77/79

CONTENTS

Technical specification ..................................................................1-2

Service measurement setup..........................................................1-3

Service aids .................................................................................1-4

Instructions on CD playability ...............................................2-1.. 2-2

Disassembly diagram............ ........................................................3-1

Block diagram ................................................................................4-1

Wiring diagram ..............................................................................4-2

Main board

Circuit diagram .........................................................................5-1

Layout diagram ..................................................................5-2..5-3

Key board

Circuit diagram .........................................................................6-1

Layout diagram ..................................................................6-2..6-3

Exploded view diagram .................................................................7-1

Mechanical parts list ......................................................................7-2

Electrical parts list...................................................................8-1..8-2

Revision list.....................................................................................9-1

All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted, in any form or by any means, electronic, mechanical, photocopying, or otherwise without the prior permission of Philips.

Published by LX 1016 Service Audio Subject to modification

Version 1.1

3141 785 32741

TECHNICAL SPECIFICATION

1 - 2

AMPLIFIER

Total output power

........................................... 25 W (12.5 W per channel)

Signal-to-noise ratio .......................... ≥ 62 dBA (IEC)

Frequency response ......... 63 – 16000 Hz, ± 3 dB

CD PLAYER

Frequency range .................................. 63 – 16000 Hz

Signal-to-noise ratio ............................................ 65 dBA

TUNER

FM wave range ...................................87.5 – 108 MHz

MW wave range ................................ 531 – 1602 kHz

SPEAKERS

1-way Bass Reflex System

Impedance ........................................................................ 8 Ω

Speaker diameter ............................................................. 4”

Dimensions (w x h x d)..........14.6x23.6x18.5 (cm)

GENERAL

AC Power ........................... 110 – 127 / 220 – 240 V;

....................................................... 50/60 Hz Switchable

Dimensions (w x h x d) ....... 14.6x23.6x23.9 (cm)

Weight (with/without speakers) ..................................

.................................................................................5.9 / 2.5 kg

Specifications and external appearance are subject to change without notice.

MEASUREMENT SETUP

Tuner FM

1-3

Bandpass

LF Voltmeter

e.g. PM2534

RF Generator

e.g. PM5326

DUT

250Hz-15kHz

e.g. 7122 707 48001

Ri=50:

S/N and distortion meter

e.g. Sound Technology ST1700B

Use a bandpass filter to eliminate hum (50Hz, 100Hz) and disturbance from the pilottone (19kHz, 38kHz).

Tuner AM (MW,LW)

RF Generator

e.g. PM5326

Ri=50:

DUT

Frame aerial

e.g. 7122 707 89001

Bandpass

250Hz-15kHz

e.g. 7122 707 48001

LF Voltmeter

e.g. PM2534

S/N and distortion meter

e.g. Sound Technology ST1700B

To avoid atmospheric interference all AM-measurements have to be carried out in a Faraday´s cage. Use a bandpass filter (or at least a high pass filter with 250Hz) to eliminate hum (50Hz, 100Hz).

Use Audio Signal Disc (replaces test disc 3)

DUT

SBC429 4822 397 30184

S/N and distortion meter

e.g. Sound Technology ST1700B

LEVEL METER

e.g. Sennheiser UPM550

Recorder

Use Universal Test Cassette CrO2 SBC419 4822 397 30069

or Universal Test Cassette

LF Generator

e.g. PM5110

Fe SBC420 4822 397 30071

DUT

S/N and distortion met

e.g. Sound Technology ST170

LEVEL METER

e.g. Sennheiser UPM550

with FF-filter

SERVICE AIDS

1-4

All ICs and many other semi-conductors are susceptible to electrostatic discharges (ESD). Careless handling during repair can reduce life drastically. When repairing, make sure that you are connected with the same potential as the mass of the set via a wrist wrap with resistance. Keep components and tools also at this potential.

WARNING

Safety regulations require that the set be restored to its original condition and that parts which are identical with those specified, be used

Safety components are marked by the symbol

ESD

CLASS 1

LASER PRODUCT

Lead free

INSTRUCTIONS ON CD PLAYABILITY

Customer complaint

"CD related problem"

Set remains closed!

check playability

2 - 1

playability

ok ?

Play a CD

for at least 10 minutes

check playability

playability

ok ?

"fast" lens cleaning

check playability

playability

ok ?

For flap loaders (= access to CD drive possible) cleaning method

4 is recommended

add Info for customer

"SET OK"

return set

1 - 4 For description - see following pages

Exchange CDM

INSTRUCTIONS ON CD PLAYABILITY

2 - 2

PLAYABILITY CHECK

For sets which are compatible with CD-RW discs

use CD-RW Printed Audio Disc ....................7104 099 96611

TR 3 (Fingerprint) TR 8 (600µ Black dot) maximum at 01:00

• playback of these two tracks without audible disturbance playing time for: Fingerprint

Black dot from 00:50 to 01:10

• jump forward/backward (search) within a reasonable time

For all other sets

use CD-DA SBC 444A..................................4822 397 30245

TR 14 (600µ Black dot) maximum at 01:15 TR 19 (Fingerprint) TR 10 (1000µ wedge)

• playback of all these tracks without audible disturbance playing time for: 1000µ wedge 10seconds

Fingerprint 10seconds Black dot from 01:05 to 01:25

• jump forward/backward (search) within a reasonable time

10seconds

LIQUID LENS CLEANING

Before touching the lens it is advised to clean the surface of the lens by blowing clean air over it. This to avoid that little particles make scratches on the lens.

Because the material of the lens is synthetic and coated with a special anti-reflectivity layer, cleaning must be done with a non-aggressive cleaning fluid. It is advised to use “Cleaning Solvent

The actuator is a very precise mechanical component and may not be damaged in order to guarantee its full function. Clean the lens gently (don’t press too hard) with a soft and clean cotton bud moistened with the special lens cleaner.

The direction of cleaning must be in the way as indicated in the picture below.

CUSTOMER INFORMATION

It is proposed to add an addendum sheet to the set which informs the customer that the set has been checked carefully - but no fault was found. The problem was obviously caused by a scratched, dirty or copy-protected CD. In case problems remain, the customer is requested to contact the workshop directly. The lens cleaning (method 3) should be mentioned in the addendum sheet.

The final wording in national language as well as the printing is under responsibility of the Regional Service Organizations.

+ 13 hidden pages