DEH-MG6347ZH/XU/UC
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6.3 CHECKING THE GRATING AFTER CHANGING THE PICKUP UNIT
•
Note :
The grating angle of the PU unit cannot be adjusted after the PU unit is changed. The PU unit in the CD mecha-
PU unit for the CD mechanism module. Changing the PU unit is thus best considered as a last resort. However,
r if
.
•
Purpose :
To check that the grating is within an acceptable range when the PU unit is changed.
•
:
If the grating is off by a large amount symptoms such as being unable to close tracking, being unable to perform
•
Method :
•
•
wo L.P.F
P
P .
• Measuring Points
• E, F, REFO
•
•
• Mode
• TEST MODE
•
Checking Procedure
and
SEEK DOWN
buttons, move the PU unit to the innermost track.
to close focus, the display should read "91". Press key
2
to implement the tracking
-
should now read "81". Press key
3
4 times. The
will change, returning to "81" on the
4. As shown in the diagram above, monitor the LPF outputs using the oscilloscope and check that the phase differ-
5. If the phase difference is determined to be
than 75
°
t
the PU unit to see if there is any
improvement. If, after trying this a number of times, the grating angle does not become less than 75
°
then the
of eccentricity in the disc and a slight misalignment of the clamping center the grating waveform may be
-
•
Hint
Reloading the disc changes the clamp position and may decrease the "wobble".
100k
Ω
390pF
100k
Ω
390pF
E
REFO
F
Xch
Ych
Oscilloscope
L.P.F.
L.P.F.
REFO
CONTROL UNIT
REFO
E
F
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