Pioneer CDX-M8027ZT/E, Руководство по обслуживанию

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D
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CDX-M8127ZT/WL
• Note :
Unlike previous CD mechanism modules the grating angle of the pickup unit cannot be adjusted after the pickup
unit is changed. The pickup unit in the CD mechanism module is adjusted on the production line to match the CD
mechanism module and is thus the best adjusted pickup unit for the CD mechanism module. Changing the pickup
unit is thus best considered as a last resort. However, if the pickup unit must be changed, the grating should be
checked using the procedure below.
• Purpose :
To check that the grating is within an acceptable range.
• Symptoms of Mal-adjustment :
If the grating is off by a large amount symptoms such as being unable to close tracking, being unable to perform
track search operations, or track searching taking a long time, may appear.
• Method :
• Measuring Equipment • Oscilloscope, Two L.P.F.
• Measuring Points • E, F, REFOUT
• Disc • ABEX TCD-784
• Mode • TEST MODE
• Checking Procedure
1. In test mode, load the disc and switch the 5V regulator on.
2. Using the TRACKUP and TRACKDOWN buttons, move the pickup unit to the innermost track.
3. Press key RPT(ch5) to close focus, the display should read "91". Press key DISCDOWN to implement the tracking
balance adjustment the display should now read "81". Press key RPT(ch5) 4 times. The display will change,
returning to "81" on the fourth press.
4. As shown in the diagram above, monitor the LPF outputs using the oscilloscope and check that the phase differ-
ence is within 75° . Refer to the photographs supplied to determine the phase angle.
5. If the phase difference is determined to be greater than 75° try changing the pickup 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
mechanism should be judged to be at fault.
• Note
Because of eccentricity in the disc and a slight misalignment of the clamping center the grating waveform may be
seen to "wobble" ( the phase difference changes as the disc rotates). The angle specified above indicates the aver-
age angle.
• Hint
Reloading the disc changes the clamp position and may decrease the "wobble".
6.2 CHECKING THE GRATING
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Checking the Grating After Changing the Pickup Unit
REFO
E
F
REFO
REFO
E
F
L.P.F.
L.P.F.
CD CORE UNIT
Xch
Ych
Oscilloscope
100k
Ω
100k
Ω
390pF
390pF