Akai X 360 DS Service Manual

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Akai X 360 DS Service Manual

Extracted text from Akai X 360 DS Service Manual (Ocr-read)


Page 1

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I. SPECIFICATIONS

POWER SUPPLY
RECORDING SY STEM

AC [00 lo 240 V, 50 or 60112

Inellne Muck stereo, monaural recording

by using Cross-field Bias Head.
TAPE SPEED 1.7/3, 3.3/4, 7-1/2 and 15 ips.
TAPE SPEED DEVIATION
Within 1 0.5% al7-1/21ps
Within i1.0% at 3—3/4 ips
Within 11.0% at 1-7/81ps
WOW AND FLU‘ITER
Less than 0.10% rims. 317-112 11):
Less than 0.13% 1'.rn.s. a! 3-3/4 'rps
Less than 025% ”11.5. at 1-7/8 ips
FREQUENCY RESPONSE
30 11) 21.000 Hz :3 1113 3174/2115:
30 to 18.000 Hz :3 (113 at 3—3/4 ips
40 10 9.000 Hz 14 dB at 1-7/8 1p:
SIGNAL TO NOISE RATIO
(at Line Oulput; Greater than 48 dB at 7-1/2 ips
Greater than 45 dB 31 3-3/4 ips
Greater than 48 dB a! 1-7/8 1ps
TOTAL HARMONIC DISTORTION
(:1: Line Output, 1.000 H1 0 VU Rec/PB)
Will'u'n 1.7% a! 7-1/2 ips
Wilhln 3.0% at 3—3/4 ips
Wlthin 3.0% at 1-7/8 ips
RECORDING INPUTS

MICROPHONE Above 0.7 mV
LINE INPUT Above 70 mV
Impedance... 166 K ahms
DIN INPUT High : 70_mV 166 K ohmx
Low: 7 11W 16 K ohms
OUTPUTS
LINE OUTPUT Required Load Impedance :

more than 50,000 011m:

1.13 V (+4 dbsi 1.5 db) at 7-1/2 ips
1.03 V (+25 (1115 t 1.5411103? 3-3/41135
0.32 V (+0.5 db: 11.5 db)3t1-7/31ps

POWER OUTPUT: External Speaker Jack

More man 10 W 31 8 ohms Non-inductive

resistance

NOISE : Less than 5 mV 111 3 ohms at External

Speaker Jack

(Volume Control 11! "Minimum" position)

FAST FORWARD AND REWIND TIME
' 75 seconds for a 111111.200 foot tape
a! 50 Hz
60 seconds for a full 1,200 foot tape
at 60111

CROSSWALK Less than —70 dB (Monaural)
Less man -43 dB (Stmo)

ERASE RATIO More than 70 dB

INSULATION DURABIUTY
500 V AC for mom drumming
duralion

BIAS FREQUENCY: 100 KHZ

MAIN MOTOR

REE]. MOTOR

HEADS
PLAYBACK HEAD

RECORDING HEAD

ERASE HEAD

Hyslcrux’s Synchronous 3 speeds
(2-4-8 pole) motor.
Condenser Cnpacily 3 AF (50 HZ). 2 #F
(60 Hz)
Revolu fions ;
LOGO—1.500450 r.p.m. (50 Hz)
3.600—I,BOO—900 r.p.m. (60 H7.)
Two 6—pole eddy current outer-rotor
molars

Rev olu lions :

930 r.p.m. a! 50 H1, 100V
1.120 r.p.rr1. 3160 HZ,120V

In-lr'ne 44nd: stereo and monaural
Impedance . . .1000 011111: at 1,000 Hz
Gap . . . 2 micmn:

1n~line +uack stereo and monaunl
Impedance. . .45 ohms at. 1.000 H1
Cap . .. 2 micmm

In-Ijne ¢-rrack stereo and mo mural
Impedance .. .330 ohms 81100 KHZ
Gap . . . 0.4 mm

CROSS-FIELD BIAS HEAD

In-line Attack stereo and momuml
Impedance. . . 4300111115 at 100 H
Gap . . . 0.4 mm *

INTERNAL SPEAKERS

TRANSISTORS USED

DIODE USED

2 4-inch Round Speakers
Nominal Power Input . 1 . 3 W. 16 ohms

1s 28C458LG®/©
2x372
25cs23©
25C538A©
zsceso®
25cm;
ZSB7SA
23B77A®
25n157
250147
BCMSR
2SCSBBRQ Main Amplifier
2SC69 era 16 «-
25013011

1mm

10D2

1004

10136

552

51,150

SL-ISM

1N759A

RIB-24A

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Xv3500 (whhouI
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Page 2

TAPE SPEED DEVI ATION

1. Method involving use of pro-recorded tape.
Playback on the tape recorder to be tested tape
pre-recorded at 1,000 Hz 2 0.1% for measuring tape
speed deviation. Connect the appropriate output to a
frequency counter meter in order to measure the tape
speed deviation from the resulting deviation of the
measured frequency.
2. Method involving use of timing tape

(designed for tape speed measurement)
This method utilizes a timing tape marked at intervals of
7-1/2". The running time of the tape over 60 marked
section is measured in order to calculate the deviation of
the tape speed. In applying this method, however, it
should be born in mind that the timing tape stretch or
contract, measurement error is inevitable, so that it is
necessary to measure the total length of the tape in
advance.

WOW AND FLUTTER
Playback the 3.000 Hz pre—recorded tape whose wow

and flutter level is guaranteed to be smaller than 0.07% '

for measurement by means of a wow meter. It is also
possible for a 3,000 l-_lz sine wave to be recorded and
played for measurement by means of the wow meter. In
this case, however, the wow meter indicates a value as
much as twice the value given in the specifications on
the first page.

FREQUENCY RESPONSE
RECORD:

l),.Give a sine wave of 1,000 Hz to the Line input of
the recorder to be tested through an attenuator
from an audio frequency generator.

2) Push the “Source Button" andadjust theline input
volume so that the W meter needle indicates “D"
W.

3) Under the condition described in (2), lower the
input level 20 db by means of the attenuator.

4) Connect a microphone to the Microphone Input.
Push the tape speed selector in 7—1/2" position.

5) Start recording. Control the microphone input level
and the spot frequency in the range of 30 Hz to
25,000 Hz from the audio frequency generator and
record by talking.

' Remarks: After announcing the frequency of
each point, the the microphone
volume should immediately be rotated
back to minimum.

PLAYBACK: ".
6) Push the “Tape Monitor Button" and “Forward
Button".
7) Set the Tape Speed Selector in 7—1/2“ position.
8) Connect a Vacuum Tube Volt Meter to the line
output jack (V.T.V.M. with milli volt scale).
9) Playback the recorded tape.
10) Playback the recorded spot frequencies and make a
memo of output level and plot the value on a graph.

Audio X969 V.T.
Fre uency: A.T.‘l‘. Lure input VM.
Osc' ator Mic.i.nput ‘
, 31— Line output
Microphone jack

TOTAL HARMONIC DISTORTION FACTOR

1 K Hz
Audio Distortion
Oscillator X'BSO meter

Connect the measuring instrument as shown above; and
record the 1,000 [-12 sine wave at “0” V1). Playback the
resultant signal and measure the overall distortion factor.
Measure the noise level of the tape recorder with the
tape removed; connect the audio oscillator directly to
the distortion meter for measurement of the distortion
factor of the oscillator.

The required distortion factor may be obtained from the
results of the above measurement by the following

formula: .

do = d—dr-i'l2
where, do = Required
:1 = Overall distortion factor
J, = Noise level
:1, = Distortion factor of the oscillator

(Note: New tape of particularly good quality should be
used for measurement of the distortion factor). 7

SIGNAL TO NOISE RATIO

Set the cone Switch on “Flat" position and Playback a

tape containing a 250 Hz sine wave recorded at “O" VU

level on a standard recorder. Connect a high sensitivity
V.T.V.M. to the line outputjack and measure its output.

output.

Then remove the tape and'mcasu re the noise level under

the same conditions. Convert into decibels each of the .
measured values.

Page 8

VI. AMPLIFIER ADJUSTMENT

' |, PLAYBACK OUTPUT LEVEL
D (Pm-amplifier) ADJUSTMENT
3) Connect a High-sensitivity V.T.V.M. to the Line
Output Jack
1;) Set the Tape Speed Selector Switch to the “7-1/2"
position.
c) Playback :I 250 Hz prerecorded tape.
d) Adjust the VR29-l (semi-fixed resistor, 50 K—B)
of the Yrs-amplifier so that Line Output Voltage
indicates 1.228 V (+4 dbm).

2. VU METER SENSITIVITY
ADJUSTMENT

After the above adjustment, adjust the VR26—l (semi-
fixed resistor 2 K—B) of Chassis Print Board (RDvS26)
so that the V0 meter needles indicate exactly O W.
denoted by dot.

3. MAIN AMPLIFIER ADJUSTMENT

:) As shown in Fig. l,connect the AM Meter(100 mA—
150 mA scale) and a resistor (89 20W) to the
External Speaker Jack.

1)) Set die Main Amplifier Volume Control to minimum
so that VR31-l and VR31—2 (semivfixed resistor
2005178) are wound counterclockwise.

c) Set the Power Switch to the “ON" position. Adjust
VR3l-l and VR31~2 so that the AM meter needle
indicates “D“.

d) The foregoing should acomplish adjustment. In this
condition Collector Voltage of 25Dl30 (Power
Output Transistor) should read 26 to 27 V, with
Collector Current at 70 to 100 mA.

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Page 9

4. RECORDING AMPLIFIER
ADJUSTMENT

Rechrding Amplifier Adjustment should be made only
after Head Adjustment (vertical and horizontal azimuth)
and Playback Amplifier Adjustments have been
performed.

a) Load a blank test tape (Scotch No. 150) on the Tape
Recmder.

b) As shown in Fig 2, connect an Audio Oscillator and
Attenuator to the Line input. Connect a High-
sensitivity VJiVM. to the Line Output.

c) Set the Tape Speed Selector to “7-1/2" and the
Monitor Switch to “TAPE” position.

d) By using the Audio Oscillatot, supply a 1.000 H1
signaL Set the tape to transport, and the Record
Interlock Button to recording mode.

e) Adjust the Line Level Control so that theVU meter
needle indicates “0” (white dot).

f) Set the Monitor Switch to "SOURCE" position.
Adjust the VRZB—l (send-fixed resistor, 20 K~B) of
Recording Amplifier Board (RD—528) so that. the
VU meter needle indicates “0" (white dot).

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Page 10

b)

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d)

h)

i)

RECORDING EQUALIZATION
CHARACTERISTICS ADJUSTMENT

For tape and meters, follow the procedure used for
the adjustment ofthe recording amplifier.

Adjust the Recording Level Control by setting the
Monitor Switch to “SOURCE“ position so that the
W meter needle indicates “0” (white dot). ,
Attenuate the Audio Oscillator signal by 20 db.
Start the tape, by pushing the Forward Button then
press the Record Button to record. The Monitor
Switch must be set to “TAPE" position

As shown in Fig. 3, increase the frequency of the
Audio Frequency Oscillator by steps from 1 KHz to
10 KHz. Adjust Bias Voltage and Bias Head angle

including the gap between Bias and Recording heads.

The V.T.V.M. which is connected to me Line
Output, should indicate the same voltage when
using l KHz to 10 KHZ.

During 7-1/2" operation, the Bias Voltage may be
adjusted by turning the white knob V1130!
(semi-fixed resistor ZK—B) of Bias Oscillator Board
(RD-530) clockwise.

This adjustment should begin when VRSO—l is fully
wound in the clockwise position.

As shown in Fig. 4, Caps A and B, which are
between the Recording and Bias Heads, whould be
about 0.2 mm

After completion of the foregoing, observe the
Recording Playback Output Voltage at l KHZ and
10 KHz. If this voltage remains constant. change the
frequency response of Audio Oscillator
continuously. Check to see that the Output
Voltages are within 3 3 dB at any condition up to
20 KHz. [f the response around 20 KHZ reads more
than t 3 dB difference when compared with
response at 10 KHz, adjust the Peaking Coil
(AKI206) of the Recording Amplifier to match the
High-range response,

if the frequency response is gained as specified,
reset the Attenuator Dial to read “0" VU. Follow
the operation as detailed in 4 (e) & (f), and

're-adjust the Recording Level of the Recoring

Amplifier to 0 W at. 1.000 H2.

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Set the Tape Speed Selector to "3-3/4” and attenuate
the Input signal to -20 dB. Adjust the VR30—2
(semi-fixed resistor 5 K—B) of Bins Oscillator Board
(RD-530) so that the responses at 1 KHZ and
10 10-1: in Recording/Playback condition, are at the
same level.

After the same response at l KHZ and lo KHz has
been gained. increase the input signal to 18 KHz by
steps. Check whether 18 KHz is within —6dB_
Distortion level at 74/2" should be within 2% and
3% at “3-3/4”.

DM DETECTOR SENSITIVITY
ADJUSTMENT

Before adjustment. remove the solder at point P
(Time Delay circuit of 15 seconds) which is shown
in Figs. 5 and 6.

Turn the Microphone Record Level Control (left
channel) slightly clockwise from the medium level
position. Then. record the non~input signal for 15
seconds.

Playback that signall Adjust VR71»1 (semi-fixed
resistor 10 K78) of DM Detector Card so that DM
indicator lamp is extinguished.

Playback a new blank tape. Adjust VR7l-l so that
the Indicator lamp lights.

Check to see that the lamp islighted when the tape
is off the Playback Head during playback Operation.
Solder Point P as shown in Figs. 5 and 6. After
soldering, the DM Indicator Lamp should light after
15 seconds following the stoppage ofinput signal to
the DM Detector circuit.

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Page 29

In)».

Recording Amplifier are decreased by the
Volume Control, and the COM Detector Card
input signal level is reduced accordingly.

When the signal level to the Recording Amplifier
is reduced to O VU, the conditions of the COM
Detector Card Transistors are again as indicated
in blue print in Figure [0, TR70-7 is cut off
and the Motor stops.

TR70-5 and TR70-6 insure that the Motor
‘stops immediately when signal level reaches
0 VU. '

0) Since the Comput-O-Matic Motor operates

onlh in the direction for decreasing the signal
level (with input signals applied), if the input
signal becomes too low, Comput—O-Matic
recording level must be reset by depressing the
Set Button “OFF" and then back “ON". At
this time, Relay MH2PM~0 is cut off (as
described in (a) above). Thus, the Volume
Control rotates toward the upper limit, auto-
matically stopping when the VU Meter indie
cator Needle registers O VU.

DM Detector

The DM Detector Circuit automatically detects the
quality of recorded sound, and when Playback level
deteriorates during recording and playback (due to
dirt, magnetic oxide, etc. on the Recording or

Playback Heads), the DM. lndicator Lamp lights.

9 KHZ is used as a drive signal {or the DM Detector
Circuit. The DM Detector Card is connected to the
[st Stage of the Playback Amplifier. as shown in
Figure ll.

The [St through the 5th Stages of the DM Detector
Circuit serve as a 9 KHZ Filler Amplifier. A 90 KHZ
Bias Trap Circuit is inserted between the 4th and
Stl't Stages to prevent operational error from
Magnetic Bias Flux during recording.

The circuitry from the 6th through the 9th Stages
serve as switching circuits. Presence of the 9 KHZ
component in Playback output signals results in the
condition printed in blue in Figure ll, Transistor
TR7l-9 stops functioning and the DM indicator
Lamp is extinguished. If the Playback Headis dirty
and no 9 KHz component is included in the
playback output signals. conditions will be as
indicated in red print in Figure ll, TRIS will be
actuated (“0N”) and the Indicator Lamp will light.
Also, if the Recording Head is dirty during record-
ing and no 9 KHz component is included in the
playback output signals, the Lamp willlight.

At 1-7/8 ips tape speed, power is cut to the DM
Detector by the Speed Selector Switch SW39—l,
thus DM Detector circuit won‘t function. During
STOP, as there is no need for the Lamp, so power is
cut to the DM Detector Circuit by Microswitch
SW207.

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