Read Sony CFD-V77S Service Manual online
— 15 —
Focus Bias Check
This check is to be done when the optical block replaced.
Check Procedure:
1. Connect the oscilloscope to test point TP (VC) and TP (RF) on
1. Connect the oscilloscope to test point TP (VC) and TP (RF) on
MAIN board.
2. Put the set into test mode.
3. Opitical pick-up setting to the center by + or – button pushing.
4. Insert disk (YEDS-18) and press
3. Opitical pick-up setting to the center by + or – button pushing.
4. Insert disk (YEDS-18) and press
^ button.
5. Press the MODE button. (Tracking servo ON)
6. Check that the oscilloscope wavewform is as shown in the figure
6. Check that the oscilloscope wavewform is as shown in the figure
below (eye pattern).
A good eye pattern means that the diamond shape (
A good eye pattern means that the diamond shape (
◊
) in the
center of the waveform can be clearly distinguished.
7. Release test mode after adjustment is completed.
• RF signal reference waveform (eye pattern)
When observing the eye pattern, set the oscilloscope for AC range
and raise vertical sensivity.
and raise vertical sensivity.
[MAIN BOARD] (Conductor side)
5-4.
REFERENCE
Focus/Tracking Gain Check
Adjustment Location : MAIN board (Component side)
(See page 16)
A frequency response analyzer is necessary in order to perform this
check exactly.
However, this gain has a margin, so even if it is slightly off, there is
no problem.
Focus/Tracking gain determines the pick-up follow-up (vertical and
horizontal) relative to mechanical noise and mechanical shock when
the 2-axis device operate.
check exactly.
However, this gain has a margin, so even if it is slightly off, there is
no problem.
Focus/Tracking gain determines the pick-up follow-up (vertical and
horizontal) relative to mechanical noise and mechanical shock when
the 2-axis device operate.
Tracking
Gain
Symptoms
Focus
• The time until music starts
becomes longer for STOP ➡
CD
CD
^ or automatic
selection (
0 , ) buttons
pressed). (Normally takes
about 2 seconds.)
about 2 seconds.)
• Music does not start and disc
continues to rotate for STOP
➡ CD ^ or automatic
selection (
➡ CD ^ or automatic
selection (
0 , ) buttons
pressed.)
• Sound is interrupted during
PLAY. Or time counter
display stops progressing.
display stops progressing.
• More noise during 2-axis
device operation.
low
—
—
high
low or high
low
low
high
Check Procedure:
1. Keep the set horizontal.
2. Inset disk (YEDS-18) and press
1. Keep the set horizontal.
2. Inset disk (YEDS-18) and press
^ button.
3. Connect an oscilloscope to TP (FE) and TP (VC) on the MAIN
board.
4. Check that the waveform is as shown in the figure below. (Focus
waveform)
VOLT/DIV : 0.2V
TIME/DIV : 500ns
TIME/DIV : 500ns
0.9Vp-p – 1.3Vp-p
TP(RF)
TP(VC)
+
–
–
Oscilloscope
(DC range)
TP
(RF)
TP(VC)
Click on the first or last page to see other CFD-V77S service manuals if exist.