D-EJ985
9
9
SECTION 4
ELECTRICAL CHECK
The CD section adjustments are done automatically in this set.
In case of operation check, confirm that focus bias.
Precautions for Check
1. Perform check 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
AVLS switch
: NORM
HOLD switch
: OFF
G•PROTECTION switch : 1
Connecting and Checking Location:
Focus Bias Check
Condition:
• Hold the set in horizontal state.
Connection:
Procedure:
1. Connect the oscilloscope to the test points TP601 (RF) and
TP418 (GND) on the MAIN board.
2. Set a disc. (YEDS-18)
3. Push the
N X
button.
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.
oscilloscope
(AC range)
+
–
MAIN board
TP601 (RF)
TP418 (GND)
2 k
Ω
RF level
0.45 to 0.65 Vp-p
TP418
(GND)
TP601 (RF)
– MAIN Board (Conductor Side) –
