Onkyo TAR 300 Service Manual

Page 1

TA-R3OO

SERIAL NO. 3327

ONKYO SERVICE MANUAL

STEREO CASSETTE
TAPE DECK
MODEL TA-R300

Black model
| UD,UI)® IZIIV AC . (3(in
UG 220v ACSOHZ 7
If uw " IZIIorZZIIV AC. sn/muz

I-EQA. nor; :

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 COM-
PONENTS WITH ONKYO PARTS WHOSE PARTS
NUMBERS APPEAR AS SHOWN IN THIS MANUAL.

MAKE LEAKAGE-CURRENT 0R RESISTANCE
MEASUREMENTS TO DETERMINE THAT
EXPOSED PARTS ARE ACCEPTABLY [Ni
SULATED FROM THE SUPPLY CIRCUIT BEFORE

RETURNING THE APPLIANCE TO THE
CUSTOMER.

Track Format: 4-tracks, 2»channels

Erasing System: AC erase

Tape Speed: 4.8 cm/sec. (1-7/8 Lps.)

Wow and Flutter: 0.07% (WFIMSI

I ONKYO.
IIIIIIII chPlllIIlIIs

249LAC. 50H; _1

Frequency Response:

S/N Ratio:

Input Jacks:

Outputs:

Motors:
Heads:

Power Supply Rating:

Power Consumption:
Dimensions:

Weight:

20717,000Hz (Normal)
(30-16,000Hz t 3GB)
20-18,000H2 (High)
(30-17,!)DOH2 :BdBI
20-19,000Hz (Metal)
(30-18,000Hz 13dB)
58dB (metal tape, Dolby NH off)
A noise reduction of 10dB above 5kHz
and 5dB at IkHz is possible with Dolby 8
NR. A noise redualon of 20dB at SkHz is
possible with Dolby C NR.
Line IN: 2
Input sensitivity: 60mV
Input impedance: 50kohms
Line OUT: 2
Standard output level: 500mV (OdB)
Optimum load impedance: over
50 kohms
Headphone jack: 1
Optimum load impedance: 8 to 200
ohms
DC servo motor: 1
DC motor: I
REC/PB: Special Hard Permalloy x 1;
Erase head: Ferrite x 1
European models:
AC 220V, 50Hz
Canadian models:
AC IZOV, 60Hz
Worldwide models:
AC 120V and 220V switchable, SO/SOHZ
19 watts
435(Wlx122lHIX 252(D) mm
(17-1/8" x 4-13/16"x10-15/16"I
4.5 kg. (9.9 lbs.)

RC-I46T Remote Control Transmitter

Transmitter:
Signal Range:
Power Supply:
Dimensions;

Weight:

Infrared

Approx. 5 meters (16 feet)

Two AAA batteries

38(WI x 150(H) x 15.3(Dl mrn
(1-1/2" x 5-7/8 x 5/8")

62 grams (2.2 02.) (including batteries)

Specifications and external appearance are subject to change
without notice because of product improvements.

Page 2

TA-R3OO

REC/PB level -)

SERVICE PROCEDURES

1. Replacement of power supply cord

There are two power supply cord outlets on the strainrelief.
Insert them in prescribed direction to ensure safety. AS-UC-
3 tUD model) should he inserted lengthwrse and
other types of cords should be inserted horizontally.

Power Supply Cord Power Supply Cord
/ 1

Horizontal

length wise
direction

direction

2. Insulating resistance measurement

Connect the insulating-resistance tester hetween the plug of
power supply cord and chassis.

Specifications: 500V more than lOMS'Z

HX PRO CIRCUIT OPERATION
EXPLANATION

I. Regarding recording frequency characteristic and bias
Ordinarily. if the recording bias current is increased. REC/PB
frequency response level in the high frequency region (about
IUKHz and above) drops. and if the bias is decreased. the
response rises.

Drop Bias decreasef

\

Frequency -

<--
Bias increase

REC/PB level

2. Regarding the basic operation ufHX PRO(Refer to Fig. I)
The HX PRO uses the ,u. PCIZ97CA IC, The operation is
in accordance with the following.

1) At (a). the recording bias is added onto the audio signal.
and the recording signal IS detected. This is the same as
the recording head recording the signal on the tape.

2) The signal of l) preserves the frequency response with
the integrated circuit of (h).

R433 +. 34.3.1...w (. I)

x C423 >< R433 >< R431

By means of the frequency of Fig. l. the frequency which
is effective from the beginning is determined. In the
ordinary situation. this is half the audio band (lthHz).
(IOKHZ ~ 7.5Kllz).

3) At (c). in order to use the affected waveform after-ward.
absolute detection is carried out.

Frequency = 9-1

Rise

/~\l

FreQUency ->

4) At (d). the waveform peak value is detected. 'I'hc output
becomes the peak DC voltage.

5) At (e), the standard voltage and the voltage of (4) are
compared.

6) With the output of (c). the frequency generation level is
controlled (voltage controlled amplifier). That is. the bias
size is varied.

7) Summing up I) ~ 6):

At (a). the time constant (frequency) that is detected in
the recording signal is preserved. and above a certain
frequency and above a certain level. the VCA controls
the bias current by causcing its reduction. thn this is
done. in the maner shown in the explanation of Item I
above. the frequency high region is raised. With this
control. the audio signal is instantaneously dealt with.

Regarding the operating conditions of the HX PRO

With equation (2. l) noted above. the effect be'gins at the
frequency thus determined.

Above a certain level the effect begins.

(Substantially 0 dB: In the vicinity of 500mV line out)
The audio signal component level is dependent upon the
waveform after point (c).