Maintenance Of Laser Pickup; Replacement Of Laser Pickup - Jvc Xl-V174Bk Service Manual

XL-V163TN/V 164BK
XL-V263TN/V264BK
Maintenance of
Laser Pickup
1. Life of the laser diode
When the life of the laser diode has expired, the
following symptoms will appear.
1) The level of RF output ( EFM output: ampli-
tude of eye pattern) will be low.
2) The drive current required by the laser diode
will be increased.
In such a case, check the life of the laser
diode following the flowchart below.
Is RF output
more than 0.7 Vp-p?
Replace it.
ls the laser
diode drive current less
than 120 mA?
Replace it.
has expired
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1-28 (No.20392)
Replacement of
Laser Pickup
Turn off the power switch and, disconnect the
power cord from the AC outlet.
Replace the pickup with a normal one. (Refer to.
Removing the laser pickup " on page 1-26.)
Plug in the power cord, and turn the power
switch on. At this time, check that the laser
emits for about 3 seconds and the objective lens
moves up and down.
Note: Do not observe the laser beam directly.
Play a disc, and when it starts rotating, short
circuit between TP2(TEST) and TP4 (GND).
'Adjust focus gain. :
Adjust tracking gain.
Disconnect TP2 (TEST) from TP4 (GND).
Check the eye-pattern at the TP3 (RF).
Finish.
Note: Since one adjustment may affect other
setnge, repeat these adjustments a few
imes.