D-EJ775
9
SECTION 4
ELECTRICAL ADJUSTMENTS
The CD section adjustments are done automatically in this set.
In case of operation check, confirm that focus bias.
PRECAUTIONS FOR ADJUSTMENT
1. Perform adjustment in the order given.
2. Use YEDS-18 disc (Part No.: 3-702-101-01) unless otherwise
indicated.
3. Power supply voltage requirement: DC4.5 V in DC IN jack.
(J401)
VOLUME
: Minimum
[SOUND]
switch
: OFF
[HOLD]
switch
: OFF
[G PROTECTION]
switch : ON
FOCUS BIAS CHECK
Condition:
• Hold the set in horizontal state.
Connection:
Procedure:
1. Connect the oscilloscope to the test points TJ503 (RF) and
TJ501 (AGND) on the MAIN board.
2. Set a disc. (YEDS-18)
3. Press the
N>
key on the remote commander.
4. Check the oscilloscope waveform is as shown below.
A good eye pattern means that the diamond shape (
◊
) in the
center of the waveform can be clearly distinguished.
RF Signal reference Waveform (Eye Pattern)
VOLT/DIV : 100 mV (With the 10:1 probe in use)
TIME/DIV : 500 ns
To watch the eye pattern, set the oscilloscope to AC range and
increase the vertical sensitivity of the oscilloscope for easy watch-
ing.
5. Stop revolving of the disc motor by pressing the
x
button.
Connection and Checking Location: MAIN Board
(See page 10)
oscilloscope
(AC range)
+
–
MAIN board
TJ503 (RF)
TJ501 (AGND)
2 k
Ω
RF level
0.4 to 1 Vp-p
•
EF ALIGNMENT ADJUSTMENT
(for microcomputer version 052 or 057 only)
Connection:
Procedure:
1. Short the solder bridge of TAP802 (OPEN) on the MAIN board.
2. Connect the TP514 (OPGSW) and TJ405 (AVDD) on the
MAIN board using a lead wire.
3. Connect the TJ805 (AD SEL) and TJ401 (MAINGND) on the
MAIN board using a lead wire.
4. Turn on the power (DC 4.5V).
5. Turn on the
[HOLD]
switch.
6. Press the
N>
key on the remote commander, and check
that “0088” is displayed on the remote commander.
7. Press the
.
key on the remote commander, and check that
“0087” is displayed on the remote commander.
8. Remove a lead wire from the TJ805 (AD SEL) and TJ401
(MAIN GND) on the MAIN board. At this time, check that
“00” is displayed on the remote commander.
9. Connect the oscilloscope to the TJ603 (MON1) and TJ610
(VBIAS) on the MAIN board.
10. Adjust the SUB board, RV1 (MAIN board suffix-11, -12) or
MAIN board, RV601 (MAIN board suffix-13) so that the volt-
age at part
A
of the oscilloscope is
±
10mV.
If “no disc” is displayed on the remote commander, press the
N>
key on the remote commander and make readjust-
ment.
Connection and Adjustment Location: MAIN/SUB Boards
(See page 10)
oscilloscope
(DC range)
+
–
MAIN board
TJ603 (MON1)
TJ610 (VBIAS)
A
0 mV
0 mV
A
±
10 mV
