Sony D-V8000, Service Manual

Page: 22 / 78

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oscilloscope
(AC range)
MAIN board
TP535 (RFO)
TP534 (VC)
(see page 23)
2 k
Ω
RF level
0.7
±
0.2 Vp-p
5-4. Focus Bias Check
Condition:
• Hold the set in horizontal state.
Connection:
Checking Method:
1. Connect the oscilloscope to TP535 (RFO) and TP534
(VC) on the MAIN board.
2. Set the equipment to service mode stop state. (See page
20.)
3. Press the
fl
key once.
4. Move the optical pick-up to the center by pressing the
±
and
≠
keys.
5. Put the disc (YEDS-18).
6. Press the
fl
key four times.
From focus searching, focus is turned ON while en-
tering CLV drawing-in mode. Both tracking and sled
are turned ON.
7. 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 : 200 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 watching.
8. Stop revolving of the disc motor by pressing the
π
key.
9. After the completion of check, reset service mode. (See
page 20.)
Connection Location: MAIN board (See page 23.)