Onkyo TARW 400 Service Manual

Page 1

ONKYO

SERVICE MANUAL

STEREO CASSETTE
TAPE DECK
MODEL TA-RW4OO

SAFETY-RELATED COMPONENT WARNING I!

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 OR RESISTANCE
MEASUREMENTS TO DETERMINE THAT
EXPOSED PARTS ARE ACCEPTABLY IN-
SULATED FROM THE SUPPLY CIRCUIT BEFORE
RETURNING THE APPLIANCE TO THE
CUSTOMER.

ON KYO.
MIIIIII IIIIMPIIIIIIIIS

Track System:
Erasing System:
Tape Speed:

Wow and Flutter:

Frequency Response:

SN Ratio:

Input Jacks:

Outputs:

Motors:
Heads:

Power Supply Rating:

Power Consumption:
Dimensions:

Weight:

TA-RW4OO

SERIAL NO. 3320

UDN, UDC, UD 120V AC. 6(le

UG 220v Ac, 50Hz

uw 120 or 220v AC, 50/60Hz

UQA, UQB 240v AC. 50Hz
SPECIFICATIONS

4-tracks. 2-channels

AC erase

4.8 cmsee. (1-78 i.p.s.)

9.6 cmsee. (3-34 i.p.s.) (high speed dub-
hing)

0.07% (WRMS)

2045.0le (Normal)

(30-141)le i3dB)

2()-16.000Hz (High)

(30-15.000Hz iSdB)

2047,0001-[2 (Metal)

(3(]»16.()(l(lllz inB)

Dolby NR off: SSdB (metal position tape)
A noise reduction of 10dB above SkHz
and SdB at lkHz is possible with Dolby B
NR. A noise reduction of 21MB at SkHz is
possible with Dolby C NR.

Line IN: 2

Input sensitivity: 60mV

Input impedance: St) kohms
Headphone jack: 1

Optimum load impedance: 8 to 200
ohms

Line OUT: 2

Standard output level: 50(va (OdB)
Optimum load impedance: over 50
kohms

DC servo motor X 2; DC motor X 2
RECIB: special hard permalloy X 2;
Erase head: ferrite X l

U.K.and Australian models:

AC 240V. 50Hz

Europian models: AC 220V. Stillz
USA, and Canadian models:

AC 120V, 60Hz

Worldwide models:

AC 120V and 220V switchable. 50/60Hz
32 watts

435(W) >< llStH) >< 334([))mm
(17-18" >< 4-12" x 13-18")
4.8 kg. (10.6 lbs.)

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

Page 2

TA-RW4OO

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 (UD<120V> model) should be inserted lengthwise and
other types of cords should be inserted horizontally.

Power Supply Cord Power Supply Cord

Horizontal

length wise .
direction

direct ion

2. Insulating resistance measurement

Connect the insulatingresistance tester between the plug of
power supply cord and chassis.

Specifications: 500V more than IOMQ

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
IOKHz and above) drops. and if the bias is decreased. the
response rises.

D'Dp Bias decrease}

\

Frequency ->

F)
>
(~- 2
Bias increase E

REC/

2. Regarding the basic operation of HX PRO (Refer to Fig. l)
The HX PRO uses the pi PCl297CA IC. The operation is
in accordance with the following.

I) 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 (b)

R450 + R448 2

_ 27: x C426 X R451! x R448 ( '1)

By means of the frequency of Fig. I. the frequency which
is effective from the beginning is determined. In the
ordinary situation, this is half the audio hand (IOKHz).
(IOKHz ~ 7.5KH2).

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

Frequency =

Fiise

/-\l

Frequency 9

4) At (d), the waveform peak value is detected. The output
becomes the peak DC voltage.

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

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

7) Summing up 1) ~ 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 causeing its reduction. When 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.

3. Regarding the operating conditions of the Ex PRO

I) With equation (2. I) noted above, the effect begins at the
frequency thus determined.

2) Above a certain level the effect begins.
(Substantially 0 dB: In the vicinity of SOOmV line out)
The audio signal component level is dependent upon the
waveform after point (c).