Akai X 355 Service Manual

Page 1

SERVIBE
MANUAL

AKAI TAPE RECORDER
MODEL

X - 355
ALSO APPLICABLE FOR MODEL X-3SSD

Page 2

TABLE OF CONTENTS

I

II
III
IV
V
VI
VII
VIII

XI

XII
XIII

SPECIFICATIONS ................................................... 1
MEASURING METHOD ................. 2
CONTROL LOCATION ............................................. 4
PROCEDURE FOR REMOVAL ................................. 5
TRANSPORT MECHANISM ....................................... 7
MECHANISM ADJUSTMENT .................................... 15
AMPLIFIER ADJUSTMENT ....................................... 18
MAINTENANCE ...................................................... 20
REPLACEMENT PARTS TABLE ................................. 22
EXPLODED VIEW OF COMPONENT PARTS --------------- 27
TROUBLE SHOOTING CHART

(AMPLIFIER SECTION) PLAYBACK TROUBLE --------- 31

(AMPLIFIER SECTION) RECORDING TROUBLE ------ 32

(MECHANICAL SECTION) ................................. 33
SCHEMATIC DIAGRAM-~- --------------- 35

CONNECTING DIAGRAM ....................................... 39

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V. TRANSPORT MECHANISM

Fig. 1 illustrates the basic circuit arrangement of the transport mechanism which is a modification of the schematic
diagram attached to the Operators Manual and which gives better understanding of the functions and operation of
the tape transport.

FIG. 1

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1. STOP

Load a tape and set the recorder to play condition. Put the power switch (SW801) to the ON position. Current
flOWS as indicated by red line in Fig. 2 and the main motor starts and the VU meter lamp lights. In this state of
tape transport, no relay or no solenoid coil is operated.

2. PLAY

As the play button is depressed under the STOP condition, the relay control current flOWS through the play button
micro switch (SW804) as indicated by red dotted line in Fig. 3 and the relay G is energized and locked by contact 6-2.
The relay G thus locked continues to he energized even with the finger released from the play button. The current
flow is shown in red line. The current floWS through contacts 7-10 and 5-3 of the relay G and into two torque motors.
The center taps of these motors are connected through the contacts of the relays A, B, C and E to the 40V terminal
of the power transformer (T702). The tape is thus given proper tension.

At the same time, the current flows into the brake solenoid and pinch wheel solenoid so that the brake band is
let free and the pinch wheel is pressed against the capstan thereby causing the tape to travel at constant rate of speed.

While in tape travel, the stop button may be depressed and the stop micro switch (SW807) put in OFF position, so
that the relay control current is discontinued and the relay G unlocked, bringing the transport mechanism to a stop.

As the tape is fully wound onto the take-up reel and the tension arm dropped, the tension switch (SW803) turns
into OFF position, thereby the transport mechanism is reverted to a stop.

_7_

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3. FAST FORWARD

Depressing now the fast forward button under the STOP condition causes the relay control current to flow through
the micro switch (SW805) as shown by red dotted line in Fig. 4 thereby switching the relay A into ON position. As
the relay A is thus locked, the relay control current flOWS along the red line in Fig. 4 until the relay G and brake
solenoid become energized to release the brakes. 120 volts are applied across 852 SW resistor to the fast forward
motor as shown in Fig. 5, whereupon the fast forward motion of the tape is effected. This resistor is intended to
prevent transient pulse generated when switching the relay contacts.

FIG. 2

FIG. 3