Onkyo T 4140 Service Manual

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ONKYO

SERIAL NO. 3251

SERVICE MANUAL

SYNTHESIZED
FM STEREO/AM TUNER

MODEL T-4140

Black model

BU D. BUDN

120V AC, 60Hz

SAFETY-RELATED COMPONENT WARNINGH
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 OR RESISTANCE
MEASUREMENTS TO DETERMINE THAT EXPOSED
PARTS ARE ACCEPTABLY INSULATED FROM
THE SUPPLY CIRCUIT BEFORE RETURNING

TIIE APPLIANCE TO THE CUSTOMER.

TABLE OF CONTENTS

Specifications --------------------

Service procedures -
Block diagram - - -
Exploded View
Pans Iist - - -
Packing View

Circuit description ----------------------
Block diagram of IC .....................
Adjustment procedures -------------------

PC board view/parts list

Dismay/Switch ...................
Main circuit View -----------------
Main circuit parts list ----------------
Schematic diagram ..................

IONKYO
\AIIIIIII BIIMPIINENIS

9
11

-~-13
NIB
...,7
.15

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SPECIFICATIONS

FM:
Tuning Range:

87.9-107l9MHz(200kHz steps)

Usable Sensitivity: Mono: llldef, 2.0pV,IHF
Stereo: 1742dBf, 4.0,uV
SOdB Quieting Sensitivity: Mono: 16.1dBf, 3.5,uV
Stereo: 36,1dBf, 35 ,uV
Capture Ratio: 1:5dB
Image Rejection Ratio: 40dB
IF Rejection Ratio: 90dB
Signal-to-Noise Ratio: Mono: 73dB
Stereo: 66dB
ACA: 50dB lHF(:400kHz)
AM Suppression Ratio: 50dB
Harmonic Distortion: Mono: 0l1%
Stereo: 02%
Frequency Response: 30-15,000Hz $1,5dB
Stereo Separation: 40dB at 1kHz
30dB at 70*10,000Hz
Output voltage: 500mV
Muting level: 17:2dBf, 4/1V
AM:
Tuning Range: 530-1,620kHz(10kl-iz steps)
Usable Sensitivity: 25;;V
Image Rejection Ratio: 40dB
IF Rejection Ratio: 30dB
Signalrto~Noise Ratio: 40dB
Harmonic Distortion: 0,896
Output voltage: 150mV
GENERAL:
Dimensions(WXH XD): 435X7I><268mm
174/ X2-13/16X10-9/16
Weight: 3.0kg.. 6,6Ibs.

Specifications and features are subject to change without notice.

SERVICE PROCEDURES

1.Safety-check out

(Only U.S.A. model)

After correcting the original service problem,perform
the following safety check before releasing the set to
the customer.

Connect the insulating-resistance tester between the
plug of power suuply cord and chassis

Specifications: 3.3Mohm 110% at 500].

2.Memroy preservation

This unit does not require memory preservation batteries.

A built-in memory power backup system preserves contents
of the memory during power failures and even when the
unit is unplugged. The unit must be plugged in and the
power switch turned on and off once in order to charge the
backrup system: Note that since this is not a permanent
memory,the power switch must be turned on and off a few
times each month to keep the back-up system operative:
The period of time during which memory contents are
preserved after power has last been turned off varies
depending on climate and placement of the unit.

On the average, memory contents are protected over a
period of 3 to 4 weeks (a minimum of 2 weeks) after

the last time power has been turned off. This period is
shorter when the unit is exposed to very high humidity or
used in an area with an extremely humid climate.

_2_

3.Change of FM/AM band step.

This model is not located the band selector switch.

If the FM band step is changed from 200kHz to 50kH2, add two diodes
(155133) to D706 and D707 on the display PC board.

If the AM band step is changed from lOkHz to 9kHz, add a diode
(155133) to D718 on the display PC board,