Checking The Grating After Changing The Pickup Unit - Pioneer DEH-P450MP Service Manual

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6.3 CHECKING THE GRATING AFTER CHANGING THE PICKUP UNIT

A
The grating angle of the PU unit cannot be adjusted after the PU unit is changed. The PU unit in the CD mechanism
module is adjusted on the production line to match the CD mechanism module and is thus the best adjusted PU
unit for the CD mechanism module. Changing the PU unit is thus best considered as a last resort. However, if the
PU unit must be changed, the grating should be checked using the procedure below.
To check that the grating is within an acceptable range when the PU unit is changed.
B
Sym m f Mal-adj
f the grating is off b a large amount s mptoms such as being unable to close tracking, being unable to perform
track search operations, or taking a long time for track searching.
M d
easuring uipment
easuring Points
Disc
ode
C
D
n
1. n test mode, load the disc and switch the
2. Using the and
. Press ke to close focus, the displa should read "91". Press ke 2 to implement the tracking balance
adjustment the displa should now read "81". Press ke
fourth press.
E
4. As shown in the diagram above, monitor the P outputs using the oscilloscope and check that the phase
difference is within 75 . Refer to the photographs supplied to determine the phase angle.
5. f the phase difference is determined to be greater than 75 tr changing the PU unit to see if there is an
improvement. f, after tr ing this a number of times, the grating angle does not become less than 75 then the
mechanism should be judged to be at fault.
Because of eccentricit in the disc and a slight misalignment of the clamping center the grating waveform ma be
seen to "wobble" the phase difference changes as the disc rotates . The angle specified above indicates the
average angle.
n
Reloading the disc changes the clamp position and ma decrease the "wobble".
F
52
1
2
m n
scilloscope, Two .P. .
, , R
AB X TCD-782
T T
CD C R U T 10 P
R 1
d
buttons, move the PU unit to the innermost track.
DEH-P450MP/XM/UC
2
3
1
D
.P. .
100k
90p
R
100k
90p
R
.P. .
regulator on.
. The displa will change, returning to "81" on the
3
4
Xch ch
scilloscope
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