Hitachi CP 900 S Service Manual

Page 2

CP-QOS/CP-QOOS I

SAFETY PRECAUTIONS

The following precautions should be observed when servicing.

1. Since many parts in the unit have special safety-related characteristics, always use genuine Hitachi's replacement
parts. Especially critical parts in the power circuit block should not be replaced with other makes.
Critical parts are marked with & in the schematic diagram and circuit board diagram.

2. Before returning a repaired unit to the customer, the service technician must thoroughly test the unit to ascertain
that it is completely safe to operate without danger of electrical shock.

3. Before returning a repaired unit to the customer, the service technician must measure the leakage-current or resist-
ance to determine that the exposed parts are acceptably insulated from the power circuit.

CONTENTS
CRQOS/CP-QOOS SYSTEM COMPONENTS ......................................... 3
DIFFERENCES BETWEEN CP-QOS AND CRQOOS .................................... 3
SYSTEM CONNECTION AND CIRCUIT OPERATION ................................. 4
1. CP-QOS ............................................................. 4
2. CRQOOS ............................................................ 7
DESCRIPTION OF NEW CIRCUIT .............................................. 10
1. SBBS (Super Bass Boost System) circuit (CP-QOS/CP-QOOS) .......................... 10
2. AC-DC combination erase head (CP-QODEX) .................................... 11
CAUTIONSON REPAIRING PRINTED RESISTOR .................................. 11
TUNER CP~90THITE/TW .................................................... 13
STER EO AMPLIFIER CP-QOS/QOOS, SYSTEM RACK CP-90R EX, SPEAKER CP-QOSP ............ 33
STEREO CASSETTE RECORDER CRQODEX ...................................... 55
DOLBY/GRAPHIC EOUALIZER CP-QIEO ................................ . ......... 69
STEREO CASSETTE PLAYER CP-QIDEX ...... . ................................... 77