Pioneer MEP-7000 Service Manual page 91

5
[4] LD (Laser Diode) Status
The degree of degradation of the laser diode (LD) mounted on the Traverse mechanism (TM) of the DVD/CD drive
can be measured using change in the current value and accumulated time of light emission (LD degradation diagnosis).
The result of diagnosis from a viewpoint of the LD current value is used for defect judgment of the Pickup Assy.
See "5.4 DEFECT JUDGMENT OF THE PICKUP ASSY."
Diagnosis from a viewpoint
of the LD current value
Diagnosis from a viewpoint
of the accumulated time
of light emission
The LD current value at the factory (INITIAL VALUE) and accumulated time of LD light emission are stored
in the main flash memory (SMAIN) of the drive unit.
Note: If the SMAIN Assy on which the data on the TM (initial value of the LD current and accumulated time of
LD light emission) have been recorded is replaced, refer to "8.4 MANUAL INPUT OF DVD/CD DRIVE DATA."
Note: If the TM is replaced, the data on the new TM must be written to the SMAIN Assy of this unit.
For details on how to write the data, see "8.2 RESET OF DVD/CD DRIVE DATA."
CURRENT VALUE
How to Read Data
INITIAL VALUE
CURRENT VALUE
5
6
If the ambient (environmental) temperature has been high, or if damaged or dirty
discs have been used for an extended period of time, the LD may be damaged. In
such a case, the LD current value will change from the one that was stored in
memory at the factory for the first time. Using this mode, an approximate degree of
degradation of the LD can be judged.
*How to proceed with degradation diagnosis with the LD current value is described
separately.
When discs in good condition are played back with this unit under ambient
(environmental) temperature of 35
Even if the usage time exceeds 7,000 hours, it is not required to replace the LD if
the above-mentioned LD current value is normal.
The LD current value that was written at the product
inspection line at the factory is displayed as the initial
value for this unit. Or, an LD current value that was
rewritten in the past, following the procedures described
in "8.2 RESET OF DVD/CD DRIVE DATA ," is displayed.
The LD current value is automatically measured each
time this unit is turned on. The measured value is
displayed as the "CURRENT VALUE."
(This value will not be written to memory.)
0000~9999
MEP-7000
6
7
, the LD has a service life of 7,000 hours.
Current (mA)
7
8
A
B
C
D
E
F
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