Sony MHC-V818 Service Manual ▷ View online
– 17 –
4. After the adjustments, apply suitable locking compound to the
parts adjusted.
Adjustment Location: Playback Head (Deck A)
Record/Playback/Erase Head (Deck B)
3. Mode: Playback
Tape Speed Adjustment (Deck A)
Note: Set the test mode using the following method and begin tape
speed adjustment.
In the test mode, the speed will switch to double speed or
normal speed each time the HI-DUB button is pressed.
In the test mode, the speed will switch to double speed or
normal speed each time the HI-DUB button is pressed.
Procedure:
With the power turned ON, press the p button, ENTER/NEXT
button, and DISC 3 button simultaneously.
(The “VOLUME” on the fluorescent display tube will blink while
in the test mode.)
To exit the test mode, press the 1/u button.
With the power turned ON, press the p button, ENTER/NEXT
button, and DISC 3 button simultaneously.
(The “VOLUME” on the fluorescent display tube will blink while
in the test mode.)
To exit the test mode, press the 1/u button.
1. Insert the WS-48B into deck B.
2. Press the · button of deck B.
3. Press the HI-DUB button and play the tape at double speed.
4. Adjust RV1001 of the LEAF SW board so that the reading of
2. Press the · button of deck B.
3. Press the HI-DUB button and play the tape at double speed.
4. Adjust RV1001 of the LEAF SW board so that the reading of
the frequency counter becomes 6000 ± 180 Hz.
5. Press the HI-DUB button and play the tape at normal speed.
6. Adjust RV1002 of the LEAF SW board so that the reading of
6. Adjust RV1002 of the LEAF SW board so that the reading of
the frequency counter becomes 3000 ± 90 Hz.
Adjustment Location: LEAF SW board
Sample Value of Wow and flutter
± 0.15% W.Peak (IEC)
0.1% W.RMS (NAB)
± 0.2% W.Peak (DIN)
0.1% W.RMS (NAB)
± 0.2% W.Peak (DIN)
Playback Level Adjustment (Deck A, Deck B)
Procedure:
Mode: Playback
Mode: Playback
Deck A is RV311 (L-CH) and RV411 (R-CH), deck B is RV301
(L-CH) and RV401 (R-CH)
so that adjustment within the following adjustment level.
(L-CH) and RV401 (R-CH)
so that adjustment within the following adjustment level.
Adjustment level:
CN301 playback level: 301.5 to 338.3 mV (–8.2 to –7.2 dB)
level difference between the channels: within ± 0.5 dB
Adjustment Location: AUDIO board
CN301 playback level: 301.5 to 338.3 mV (–8.2 to –7.2 dB)
level difference between the channels: within ± 0.5 dB
Adjustment Location: AUDIO board
test tape
P-4-A100
(10kHz, –10dB)
P-4-A100
(10kHz, –10dB)
oscilloscope
set
L
R
Waveform of oscilloscope
in phase
45
°
90
°
135
°
180
°
good
wrong
main board
CN301
Pin
CN301
Pin
1
(L-CH)
Pin
2
(GND)
Pin
3
(R-CH)
Reverse
Foward
1
Remove the four claws
2
Window
test tape
P-4-L300
(315Hz, 0dB)
P-4-L300
(315Hz, 0dB)
level meter
set
main board
CN301
Pin
CN301
Pin
1
(L-CH)
Pin
3
(R-CH)
RV1002
RV1001
RV1002(Normal Speed)
RV1001(High Speed)
Adjustment Location
[LEAF SW BOARD]
[LEAF SW BOARD]
– 18 –
Record Bias Adjustment (Deck B)
Procedure:
INTRODUCTION
When set to the test mode performed in
When set to the test mode performed in
Tape Speed Adjust-
ment
,
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 ad-
justment. During recording, the input signal FUNCTION will auto-
matically switch to VIDEO.
(After recording, press the – 0 button without stopping will
return to the position where recording was started.)
set.
This “REC memory mode” is convenient for performing this ad-
justment. During recording, the input signal FUNCTION will auto-
matically switch to VIDEO.
(After recording, press the – 0 button without stopping will
return to the position where recording was started.)
1. Press FUNCTION 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, press the r REC button, and then
press the ( button to start recording.
3. Mode: Record
5. Confirm playback the signal recorded in step 2 become adjust-
ment level as follows.
If these levels do not adjustment level, adjust the RV341 (L-CH)
and RV441 (R-CH) on the AUDIO board to repeat steps 3 and 4.
If these levels do not adjustment level, adjust the RV341 (L-CH)
and RV441 (R-CH) on the AUDIO board to repeat steps 3 and 4.
Adjustment level: The playback output of 10 kHz level difference
against 315 Hz reference should be ± 1.0 dB.
Adjustment Location: AUDIO board
Record Level Adjustment (Deck B)
Procedure:
INTRODUCTION
When set to the test mode performed in
When set to the test mode performed in
Tape Speed Adjust-
ment
, 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 au-
tomatically switch to VIDEO.
(After recording, press the – 0 button without stopping will
return to the position where recording was started.)
set.
This “REC memory mode” is convenient for performing this
adjustment. During recording, the input signal FUNCTION will au-
tomatically switch to VIDEO.
(After recording, press the – 0 button without stopping will
return to the position where recording was started.)
1. Press FUNCTION 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, press the r REC button, and then
press the ( button to start recording.
3. Mode: Record
4. Mode: Playback
5. Confirm playback the signal recorded in step 2 become adjust-
ment level as follows.
If these levels do not adjustment level, adjust the RV301 (L-CH)
and RV351 (R-CH) on the MAIN board to repeat steps 3 and 4.
If these levels do not adjustment level, adjust the RV301 (L-CH)
and RV351 (R-CH) on the MAIN board to repeat steps 3 and 4.
Adjustment level:
CN403 playback level: 47.2 to 53.0 mV (–24.3 to –23.3 dB)
CN403 playback level: 47.2 to 53.0 mV (–24.3 to –23.3 dB)
Adjustment Location: MAIN board
Adjustment Location:
[AUDIO BOARD] (Conductor Side)
4. Mode: Playback
AF OSC
VIDEO (AUDIO) IN
1) 315 Hz
2) 10 kHz
1) 315 Hz
2) 10 kHz
blank tape
CS-123
CS-123
set
attenuator
600
Ω
} 50 mV (–23.8 dB)
recorded
position
position
level meter
set
main board
CN301
Pin
CN301
Pin
1
(L-CH)
Pin
3
(R-CH)
AF OSC
VIDEO (AUDIO) IN
315Hz 50 mV (–23.8 dB)
315Hz 50 mV (–23.8 dB)
blank tape
CS-123
CS-123
set
attenuator
600
Ω
recorded
position
position
level meter
set
main board
CN301
Pin
CN301
Pin
1
(L-CH)
Pin
3
(R-CH)
RV301
Record Level (Lch)
Record Level (Lch)
RV351
Record Level (Rch)
Record Level (Rch)
IC301
CN301
1 3
[MAIN BOARD] (Conductor Side)
RV441 RV341
RV301(Lch),RV401(Rch)
Playback Level (Deck B)
Playback Level (Deck B)
RV301 RV401
RV341(Lch),RV441(Rch)
Record Bias
Record Bias
RV311(Lch),RV411(Rch)
Playback Level (Deck A)
Playback Level (Deck A)
RV311
RV411
– 19 –
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
3. Use an oscilloscope with more than 10M
Ω
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.
checks.
S Curve Check
Procedure :
1. Connect oscilloscope to test point TP (FE) on BD board.
2. Connect between test point TP (FEI) and TP (VC) by lead wire.
3. Turned Power switch on.
4. Put disc (YEDS-18) in and turned Power switch on again and
1. Connect oscilloscope to test point TP (FE) on BD board.
2. Connect between test point TP (FEI) and TP (VC) by lead wire.
3. Turned Power switch on.
4. Put disc (YEDS-18) in and turned Power switch on again and
actuate the focus search. (actuate the focus search when disc
table is moving in and out.)
table is moving in and out.)
5. Check the oscilloscope waveform (S-curve) is symmetrical be-
tween A and B.
And confirm peak to peak level within 3±1 Vp-p.
And confirm peak to peak level within 3±1 Vp-p.
S-curve waveform
oscilloscope
BD board
TP (FE)
TP (VC)
TP (VC)
+
–
–
symmetry
A
B
Within 3
±
1 Vp-p
6. After check, remove the lead wire connected in step 2.
Note : • Try to measure several times to make sure than the ratio
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 bright-
ness to obtain best waveform.
RF Level Check
oscilloscope
BD board
TP (RF)
TP (VC)
TP (VC)
+
–
–
Procedure :
1. Connect oscilloscope to test point TP (RF) on BD board.
2. Turned Power switch on.
3. Put disc (YEDS-18) in to play the number five track.
4. Confirm that oscilloscope waveform is clear and check RF sig-
1. Connect oscilloscope to test point TP (RF) on BD board.
2. Turned Power switch on.
3. Put disc (YEDS-18) in to play the number five track.
4. Confirm that oscilloscope waveform is clear and check RF sig-
nal level is correct or not.
VOLT/DIV : 200mV
TIME/DIV : 500ns
TIME/DIV : 500ns
level : 1.3 Vp-p
+0.25
–0.20
–0.20
oscilloscope
BD board
TP (TE)
TP (VC)
TP (VC)
+
–
–
E-F Balance (Traverse) Check (Without remote comander)
Procedure :
1. Short-circuit SL502 of the video board to GND.
2. Connect oscilloscpe to test point TP (TE) on BD board.
3. Turned Power switch on. Press FUNCTION button to select
1. Short-circuit SL502 of the video board to GND.
2. Connect oscilloscpe to test point TP (TE) on BD board.
3. Turned Power switch on. Press FUNCTION button to select
CD.
4. Set a disc (YEDS-18) and play.
5. Press the PLAY MODE button.
5. Press the PLAY MODE button.
(The sledding servo is turned OFF.)
6. Check the level B of the oscilliscope’s waveform and the A (DC
voltage) of the center of the Traverse waveform.
Confirm the following :
A/B x 100 = less than ± 7%
Confirm the following :
A/B x 100 = less than ± 7%
Traverse waveform
0V
level : 500 mV
±
100 mVp-p
A (DC voltage)
Center of the waveform
B
7. Press the PLAY MODE button. (The tracking servo and sledding
servo are turned ON.) Confirm the C (DC voltage) is almost
equal to the A (DC voltage) is step 6.
equal to the A (DC voltage) is step 6.
Traverse waveform
0V
C (DC
voltage)
voltage)
Sled servo
OFF
OFF
Sled servo
ON
ON
Note : A clear RF signal waveform means that the shape “
◊
” can
be clearly distinguished at the center of the waveform.
RF signal waveform
– 20 –
E-F Balance (Traverse) Check (With remote commander)
oscilloscope
BD board
TP (TE)
TP (VC)
TP (VC)
+
–
–
Procedure :
1. Connect oscilloscpe to test point TP (TE) on BD board.
2. Short-circuit SL502 of the video board to GND.
3. Turned Power switch on. Press FUNCTION button to select
1. Connect oscilloscpe to test point TP (TE) on BD board.
2. Short-circuit SL502 of the video board to GND.
3. Turned Power switch on. Press FUNCTION button to select
CD.
4. Put disc (YEDS-18) in to play the number five track.
5. Press the PLAY MODE button. (The tracking servo and the
5. Press the PLAY MODE button. (The tracking servo and the
sledding servo are turned OFF.)
6. Check the level B of the oscilliscope's waveform and the A (DC
voltage) of the center of the Traverse waveform.
Confirm the following :
A/B x 100 = less than ± 22%
Confirm the following :
A/B x 100 = less than ± 22%
Traverse waveform
Adjustment Location :
[ BD BOARD ] – SIDE A –
TP
(TE)
TP
(FEI)
TP
(FE)
TP
(RF)
TP
(VC)
0V
C (DC
voltage)
voltage)
Tracking servo
Sled servo
OFF
Sled servo
OFF
Tracking servo
Sled servo
ON
Sled servo
ON
0V
level : 1.3
±
0.6 Vp-p
A (DC voltage)
Center of the waveform
B
7. Press the PLAY MODE button. (The tracking servo and sled-
ding servo are turned ON.) Confirm the C (DC voltage) is almost
equal to the A (DC voltage) is step 7.
equal to the A (DC voltage) is step 7.
Traverse waveform
8. Desolder the short-land (SL502) short-circuited at step 2.
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