Onkyo T 488 F Service Manual

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T-488F

Ref. No.3441

ONKYO SERVICE MANUAL

SYNTHESIZED
FM STEREO/AM TUNER

MODEL T-488F

Black and Silver models

BHUP,BHUPF,UP,UPF [230V AC,50/60HZ

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

THE APPLIANCE TO THE CUSTOMER

TABLE OF CONTENTS

Specifications.
Service guide ........................................ 2
Block diagram ........................................ 3
Parts list ........................................... 5
Microprocessor connection diagram .................... 6
Microprocessor terminal descriptions ................. 7
IC block diagrams and descriptions ................... 8
Adjustment procedures ............................... 12
Printed circuit board view .......................... 15
Main circuit ...................................... 15
Other Circuits .................................... 21
Schematic diagram ................................... 17
Printed Circuit boardrparts list .................... 23
Packing view ........................................ 26

I ONKYO
AIIIIIII [IIIMIIIIIIIIIS

_1_

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T-488F

SPECIFICATIONS

FM
Tuning Range: 87.50 -- 108.00MH1

(50/25kHz steps)

Usable Sensitivity: Mono: 10.3d8t, 0 SpV, 75 Ohms IHF
0.8)tV 75 Ohms DIN
Stereo: 172(2le zopv, 75 Ohms IHF

ZOtIV 75 Ohms DIN

SOdB Quieting Sensitivity: Mono: 16.1dBf 1.7ttV 75 Ohms

Stereo: 36.1dBI 17pV 75 Ohms
Capture Ratio: 1.3dB
Image Rejection Ratio: 100GB
IF Rejection Ratio: tOOdB
Signal-to-Notse Ratio: Mono: 85dB IHF
Stereo: 77dB IHF
Selectivity: 70dB DIN (: 300kHz, 40kHz dev. Super
Narrow)

AM Suppression Ratio: 55dB

Total Harmonic Distortion: Mono: 0.03% (Wide)
Stereo: 007% (Wide)

30 - 15,000HZ (+0.5. -i.OdB)
45dB at 1kHz (Wide)

33:18 at 70 - 10.000H2 (Wide)
0.75V

17.2dBf 2.0tiV, 75 Ohms

Frequency Response:
Stereo Separation:

Output Voltage:
Muting Level:

SERVICE PROCEDURES

1. Safety-check out
After correcting the original servrce problem, perform the
following safety check before releasing the set to the
customer.
Connect the insulating-resistance tester between the plug
of power supply cord and chassrs.

Specifications: More than IOMQ at 500V.

2. Memory preservation

This unit does not require memory preservation batteries.
A built-in memory power back-up 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
change the back-up 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

AM:

Tuning Range: 522 --1611kHz (9kHz steps)
Usable Sensitivity: ZSuV

Image Rejection Ratio: 40:18

IF Rejection Ratio: 40:18

Signal-to-Noise Ratio: 40dB
Total Harmonic Distortion: 0.7%
Output Voltage: 150mV

General

Power Supply: AC 230V, 50Hz
Dimensions (W x H x D): 455 x 90 x 360 mm
Weight: 5.2 kg. 11.5 lbs.

Specifications and features are subject to change without notice:

3. Changing the AM band step
When change the band step. refer the table as shown below.
BandyStep .1826 1
IOkHz a 9kHz iShort I
9kHz a IOkHz Cut I

Q 7 0 1
MICRDPROCESSDR

xxx:
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anvil»

steam

DIGITAL CIRCUIT PC BOARD