Onkyo TX 840 Service Manual

Page 1

SERIAL No. 3331

ONKYO SERVICE MANUAL

QUARTZ SYNTHESIZED
TUNER AMPLIFIER
MODELS TX-840/TX-84OM

Black model
BHUD, BHUDN, MBHUDN 120V AC, 60H:
_I
BHUG 220V AC, SOHz
BHUW 120/220V AC, SO/60Hz

SAFETY-RELATED COMPONENT WARNING! !
COMPONENTS IDENTIFIED BY MARK A ON
THE SCHEMATIC DIAGRAM AND IN THE PARTS
LIST ARE CRITICAL FOR RISK OF FIRE AND
ELECTRIC SHOCK. REPLACE THESE COMPO
NENTS WITH ONKYO PARTS WHOSE PART
NUMBERS APPEAR AS SHOWN IN THIS
MANUAL.

MAKE LEAKAGECURRENT 0R RESISTANCE
MEASUREMENTS TO DETERMINE THAT EXPOSED
PARTS ARE ACCEPTABLY INSULATED FROM
THE SUPPLY CIRCUIT BEFORE RETURNING

THE APPLIANCE TO THE CUSTOMER.

ONKYO
AIIIIIII IIIIMPIIIIEIIIS

TABLE OF CONTENTS

Specifications ........................ 2
Service procedures --------------------- 3
Exploded View ~~~~~~ , .................. 4
Parts list ........................... 5
Block diagram 7120\7 model ----------------- 6
Block diagram ~220V model ----------------- 8
Connection diagram of microprocessor ---------- 10
Block diagram of IC ------------------- 11
Adjustment procedures ------------------- 18
Pc board view/parts list
Display/preamp./speaker ~~~~~~~~~~~~~~~~~~ 21
AM/FM tuner and selector circuit ------------ 25
Power amplifier -------------------- 30
Other pc buards --------------------- 3;;
Schematic diagram
120V model 'Tunerr ------------------- 23
120V model 'Amp. ................ 27
Other models Tuner ------------------ 3]
Other models rAmpi ................... 35
Disassembling procedures ------------------ 37
Packing View ........................ 3x

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