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Model
HCD-DX90 MHC-DX90
Pages
64
Size
7.06 MB
Type
PDF
Document
Service Manual
Brand
Device
Audio
File
hcd-dx90-mhc-dx90.pdf
Date

Sony HCD-DX90 / MHC-DX90 Service Manual ▷ View online

16
HCD-DX90
SECTION  5
MECHANICAL  ADJUSTMENTS
SECTION  6
ELECTRICAL  ADJUSTMENTS
0 dB=0.775 V
DECK  SECTION
1. Demagnetize the record/playback head with a head
demagnetizer.
2. Do not use a magnetized screwdriver for the adjustments.
3. After the adjustments, apply suitable locking compound to the
parts adjust.
4. The adjustments should be performed with the rated power
supply voltage unless otherwise noted.
5. The adjustments should be performed in the order given in this
service manual.  (As a general rule, playback circuit adjustment
should be completed before performing recording circuit
adjustment.)
6. The adjustments should be performed for both L-CH and R-
CH.
7. Switches and controls should be set as follows unless otherwise
specified.
• Test Tape
Record/Playback Head Azimuth Adjustment
Tape
Signal
Used for
P-4-A100
10 kHz, –10 dB
Azimuth Adjustment
WS-48B
3 kHz, 0 dB
Tape Speed Adjustment
P-4-L300
315 Hz, 0 dB
Level Adjustment
DECK A      DECK B
Note:
  Perform this adjustments for both decks
Procedure:
1. Mode:  Playback
Precaution
1. Clean the following parts with a denatured alcohol-moistened
swab:
record/playback heads
pinch rollers
erase head
rubber belts
capstan
idlers
2. Demagnetize the record/playback head with a head
demagnetizer.
3. Do not use a magnetized screwdriver for the adjustments.
4. After the adjustments, apply suitable locking compound to the
parts adjusted.
5. The adjustments should be performed with the rated power
supply voltage unless otherwise noted.
Torque Measurement
set
main board
CN301
Pin 
3 (L-CH)
Pin 
1 (R-CH)
main board
CN301
Pin 
2 (GND)
+
level meter
test tape
P-4-A100
(10 kHz, –10 dB)
3.06 N • m to 6.96 N • m
31 to 71 g • cm
(0.43 – 0.98 oz • inch)
0.19 N • m to 0.58 N • m
2 to 6 g • cm
(0.02 – 0.08 oz • inch)
3.06 N • m to 6.96 N • m
31 to 71 g • cm
(0.43 – 0.98 oz • inch)
0.19 N • m to 0.58 N • m
2 to 6 g • cm
(0.02 – 0.08 oz • inch)
6.96 N • m to 14.02 N • m
71 to 143 g • cm
(0.98 – 1.99 oz • inch)
9.80 N • m
100 g or more
(3.53 oz or more)
9.80 N • m
100 g or more
(3.53 oz or more)
Mode
Torque meter
CQ-102C
CQ-102C
CQ-102RC
CQ-102RC
CQ-201B
CQ-403A
CQ-403R
Meter reading
FWD
FWD
back tension
REV
REV
back tension
FF/REW
FWD tension
REV tension
17
HCD-DX90
2. Turn the adjustment screw and check output peaks. If the peaks
do not match for L-CH and R-CH, turn the adjustment screw
so that outputs match within 1dB of peak.
3. Mode:  Playback
4. After the adjustments, apply suitable locking compound to the
pats adjusted.
Adjustment Location: Playback Head (Deck A).
Record/Playback/Erase Head (Deck B).
Tape Speed Adjustment
DECK B
Note:
Start the Tape Speed adjustment as below after setting to the test
mode.
In the test mode, the tape speed is high during pressing the
 CD SYNC HI-DUB 
 button.
Procedure:
1. Turn the power switch on.
2. Press the x button,  ENTER  button and  DISC 3  button
simultaneously.
(The “TEST MODE” on the fluorescent indicator tube display
while in the test mode.)
To exit from the test mode, press the ?/1 button.
Mode:  Playback
1. Insert the WS-48B into the deck B.
2. Press the gG button on the deck B.
3. Press the  CD SYNC HI-DUB  button in playback mode.
Then at HIGH speed mode.
4. Adjust RV1001 on the LEAF SW board do that frequency
counter reads 6,000 
±
 30 Hz.
5. Press the  CD SYNC HI-DUB  button.
Then back to NORMAL speed mode.
6. Adjust RV1002 on the LEAF SW board so that frequency
counter reads 3,000 
±
 15 Hz.
Adjustment Location:  LEAF SW board
Playback level Adjustment
DECK A      DECK B
Procedure:
Mode:  Playback
Deck A is RV302 (L-CH) and RV352 (R-CH), Deck B is RV303
(L-CH) and RV353 (R-CH) so that adjustment within adjustment
level as follows.
Adjustment Level:
CN301 PB level:  301.5 to 338.3 mV (–8.2 to  –7.2 dB) level
difference between the channels:  within 
±
0.5 dB
Adjustment Location:  MAIN board
Sample Volue of Wow and Flutter: 0.3% or less W. RMS
(WS-48B)
Screw
position
L-CH
peak
within
1dB
Output
level
L-CH
peak
R-CH
peak
within
1dB
Screw
position
R-CH
peak
MAIN
board
CN301
set
test tape
P-4-A100
(10 kHz, –10 dB)
pin 1
oscilloscope
L-CH
R-CH
V
H
waveform of oscilloscope
in phase 45
°
90
°
135
°
180
°
good
wrong
pin 2
pin 3
L
R
+
set
test tape
WS-48B 
(3 kHz, 0 dB)
main board
CN301 (Pin 
3 : L-CH)
(Pin 1 : R-CH)
frequency counter
+
set
test tape
P-4-L300
(315 Hz, 0 dB)
main board
CN301 (Pin 
: L-CH)
(Pin : R-CH)
level meter
forward
reverse
18
HCD-DX90
4. Mode:  Record
5. Mode:  Playback
6. Confirm playback the signal recorded in step 3 become
adjustable level as follows.
If these levels do not adjustable level, adjustment the RV301
(L-CH) and RV351 (R-CH) on the MAIN board to repeat steps
4 and 5.
Adjustable level:
CN301 PB level:  47.2 to 53.0 mV (–24.3 to –23.3 dB)
Adjustment Location:  MAIN board
[MAIN  BOARD] (Component Side)
[LEAF  SW  BOARD]  (Component Side)
REC Bias Adjustment
   DECK B
Procedure:
INTRODUCTION
When set to the test mode performed in 
Tape Speed Adjustment
,
when the tape is rewound after recording, the “REC memory mode”
which rewinds only the recorded portion and playback is set.
This  “REC memory mode” is convenient for performing this
adjustment. During recording, the input signal FUNCTION will
automatically switch to VIDEO.
(If do not operation of stopped from recording complete, and rotette
of shuttle knob then rewind to recording start position.)
1. Press  MD/VIDEO  button to select VIDEO. (This step is not
necessary if the above test mode has already been set.)
2. Insert a tape into deck B.
3. After press  REC PAUSE/START  button, press REC PAUSE/
START button, then recording start.
4. Mode:  Record
5. Mode:  Playback
6. Confirm playback the signal recorded in step 3 become
adjustable level as follows.
If these levels do not adjustable level, adjustment the RV304
(L-CH) and RV354 (R-CH) on the AUDIO board to repeat steps
4 and 5.
Adjustable level: Playback output of 315 Hz to playback output
of 10 kHz:  
±
1.0 dB
Adjustment Location:  MAIN board
REC Level Adjustment
   DECK B
Procedure:
INTRODUCTION
When set to the test mode performed in 
Tape Speed Adjustment
,
when the tape is rewound after recording, the “REC memory mode”
which rewinds only the recorded portion and playback is set.
This  “REC memory mode” is convenient for performing this
adjustment. During recording, the input signal FUNCTION will
automatically switch to VIDEO.
(If do not operation of stopped from recording complete, and rotate
of shuttle knob then rewind to recording start position.)
1. Press  MD/VIDEO  button to select VIDEO. (This step is not
necessary if the above test mode has already been set.)
2. Insert a tape into deck B.
3. After press  REC PAUSE/START  button, press REC PAUSE/
START button, then recording start.
attenuator
set
MD/VIDEO (AUDIO) IN
1) 315 Hz
2) 10 kHz
50 mV (–23.8 dB)
600 
blank tape
CN-123
AF OSC
+
set
recorded
portion
CN301 (Pin : L-CH)
(Pin : R-CH)
level meter
set
MD/VIDEO (AUDIO) IN
315 Hz, 50 mV (–23.8 dB)
blank tape
CS-123
600 
attenuator
AF OSC
+
set
recorded
portion
CN301 (Pin : L-CH)
(Pin : R-CH)
level meter
TAPE SPEED
RV1002
RV1001
(NORMAL)  (HIGH)
CN1001
T601
RV611
RV351
RV354
RV304
RV303
RV352
RV302
RV353
RV301
CN301
CN304
CN302
CN303
1
3
REC LEVEL (L)
(B)
PB LEVEL (L)
(B)
PB LEVEL (R)
(A)
PB LEVEL (L)
(A)
PB LEVEL (R)
(B)
REC LEVEL (R)
(A)
REC LEVEL (L)
(A)
REC LEVEL (R)
(B)
19
HCD-DX90
FM Tuned Level Adjustment
Procedure:
1.
Supply a 28 dB 98 MHz signal from the ANTENNA terminal.
2.
Tune the set to 98 MHz.
3.
Adjust RV611 to the point (moment) when the TUNED
indicator will change from going off to going on.
Adjustment Location: MAIN board
Null Adjustment
Procedure:
1.
Supply a 60 dB 98 MHz signal from the ANTENNA terminal.
2.
Tune the set to 98 MHz.
3.
Measure voltage between pin 21 of IC 601.  Adjust T601 ubtil
the voltage becomes 0 V.
Adjustment Location: MAIN board
Adjustment Location
[MAIN BOARD]   Component side
FM RF SSG
75 
 coaxial
Carrier frequency : 98 MHz
Modulation           : AUDIO 1 kHz, 75 kHz
                              deviation (100%)
Output level          : 28 dB  (at 75 W open)
FM ANTENNA terminal
(TM601)
set
FM RF SSG
75 
 coaxial
Carrier frequency : 98 MHz
Modulation           : AUDIO 1 kHz, 75 kHz
                              deviation (100%)
Output level          : 60 dB  (at 75 W open)
FM ANTENNA terminal
(TM601)
set
CD SECTION
Note :
1. CD Block is basically designed to operate without adjustment.
Therefore, check each item in order given.
2. Use YEDS-18 disc (3-702-101-01) unless otherwise indicated.
3. Use an oscilloscope with more than 10M
 impedance.
4. Clean the object lens by an applicator with neutral detergent
when the signal level is low than specified value with the
following checks.
S-Curve Check
Procedure :
1. Connect oscilloscope to TP (FEO).
2. Connect between TP (FEI) and TP (VC) by lead wire.
3. Connect between TP (AGCCON) and TP (GND) by lead wire.
4. Turn Power switch on.
5. Load a disc (YEDS-18) and actuate the focus search. (In
consequence of open and close the disc tray, actuate the focus
search)
6. Confirm that the oscilloscope waveform (S-curve) is
symmetrical between A and B. And confirm peak to peak level
within 4 
±
1 Vp-p.
7. After check, remove the lead wire connected in step 2 and 3.
Note :
• Try to measure several times to make sure than the ratio
of A : B or B : A is more than 10 : 7.
• Take sweep time as long as possible and light up the
brightness to obtain best waveform.
RF Level Check
Procedure :
1. Connect oscilloscope to TP (RF).
2. Connect between TP (AGCCON) and TP (GND) by lead wire.
3. Turned Power switch on.
4. Load a disc (YEDS-18) and playback.
5. Confirm that oscilloscope waveform is clear and check RF signal
level is correct or not.
6. After check, remove the lead wire connected in step 2.
BD board
Oscilloscope
TP(FEO)
TP(VC)
symmetry
S-curve waveform
within 4 
±
1Vp-p
A
B
TP(RF)
TP(VC)
BD board
oscilloscope
T601
RV611
RV351
RV354
RV304
RV303
RV352
RV302
RV353
RV301
CN301
CN304
CN302
CN303
1
3
NULL
FM TUNED LEVEL
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