Cd Section - Sony ICF-CD820 Service Manual

CD SECTION

Note:
Tracking Balance Adjustment and Tracking Gain Adjustment are
done automatically in this set.
TEST MODE
1. Set the open switch (S420) to the CLOSE position.
2. Under POWER OFF condition (when the clock appear in the
display), short the TEST terminal.
Note: If the power is supplied to the microprocessor once, it is backed up
for 3 minutes, and therefore the TEST mode will not be activated
within 3 minutes even if the power is turned on again. In this case,
short instantaneously the test point RST and GND.
3. Press the CD ^ key, and the focus search is repeated.
At this time, check that the optical pickup objective lens moves
smoothly without a sticking or noise.
4. Load the test disc (YEDS-18,Part No. 3-702-101-01), and per-
form automatic adjustment after the focus search succeded.
5. After automatic adjustment is finished, move the sled motor
to the center. At this time, keep pressing the + and =
keys to confirm that optical pickup moves smoothly via most
inside track → most outside track → most inside track with-
out a sticking or noise.
6. Confirm the traverse waveform.
7. Press the WAKE UP TRACK key.
8. The tracking servo and the sled servo are turned on, the mute
is cancelled, the test pattern display on, LCD disappears, and
normal CD mode becomes active.
9. Adjust the RF and jitter waveforms.
LCD Display
CD
Tracking
Gain
Connecting points: MAIN Board (See page 13)
TRACK
49
Tracking
Balance
Focus Bias Adjustment
This adjustment is to be done when the optical block is replaced.
Connection:
MAIN board
TP (RF)
TP (VREF)
Adjustment Procedure:
1. Connect the oscilloscope to test point TP (VREF) and TP (RF)
on MAIN board.
2. Insert the disc (YEDS-18, Part No.3-702-101-01) and press
CD ^ key to play.
3. Move the optical pick-up to the music area on the disc to en-
able easy visibility of the eye pattern by + and = button
pressing.
4. Adjust RV501 so that the oscilloscope waveform is as shown
in the figure below (eye pattern).
A god eye pattern means that the diamond shape (≈) in the
center of the waveform can be clearly distinguished.
• RF signal reference waveform (eye pattern)
When observing the eye pattern, set the oscilloscope
for AC range and raise vertical sensitivity.
Adjustment Location: MAIN Board (See page 13)
– 11 –
oscilloscope
(AC range)
+
–
VOLT/DIV: 0.2 V
TIME/DIV: 500 ns
1.3 ± 0.5 Vp-p