Sony HCD-TB20 Service Manual page 24

HCD-TB20
3. Mode: Playback
test tape
P-4-A100
(10kHz, –10dB)
set
Pin 9 or TP46 (R-CH)
Waveform of oscilloscope
45 °
in phase
good
4. After the adjustments, apply suitable locking compound to the
parts adjusted.
Adjustment Location: Record/Playback/Erase Head
Tape Speed Check
Note: Set the test mode using the following method and begin tape
speed adjustment.
Procedure:
With the power turned on, press the x button, ENTER button,
and CD 3 button simultaneously.
(The message "MD" is displayed while in the test mode.)
To exit the test mode, press the "/1 button.
1. Insert the WS-48B into deck.
Press the Y button of deck.
2.
3. Check the reading of frequency counter becomes 3000 ± 90 Hz.
Sample Value of Wow and flutter
W.RMS (JIS) less than 0.3%
(test tape: WS-48B)
Adjustment Location:
[MAIN BOARD]
24
MAIN board
CN322
Pin 5 or TP42 (L-CH)
oscilloscope
Pin 6 (GND)
L
R
90 ° 135 ° 180 °
wrong
CN322
11 1
TP42
TP46
Record Bias Adjustment
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 MD.
(After recording, turn the m/M knob without stopping will
return to the position where recording was started.)
1. Press FUNCTION button to select MD. (This step is not
necessary if the above test mode has already been set.)
2. Insert a tape into deck, press the REC PAUSE/START button,
and then press the Y button to start recording.
3. Mode: Record
MD IN
1) 315 Hz
2) 10 kHz
AF OSC
600 Ω
attenuator
4. Mode: Playback
recorded
position
set
5. Confirm playback the signal recorded in step 2 become
adjustment level as follows.
If these levels do not adjustment level, adjust the RV653 (L-CH)
and RV603 (R-CH) on the TC board to repeat steps 3 and 4.
Adjustment level: The playback output of 10 kHz level difference
against 315 Hz reference should be 0 ± 0.5 dB.
[TC BOARD]
Record Bias
RV653 RV603
(L-CH) (R-CH)
} 50 mV (–23.8 dB)
blank tape
CS-123
set
level meter
MAIN board
CN322
Pin 5 or TP42 (L-CH)
Pin 9 or TP46 (R-ch)
RV652
(L-CH)
Record Level
RV602
(R-CH)