JVC KD-LH3150 Service Manual page 26

KD-LH3150, KD-LH3100
QQ
3 7 63 1515 0
3.3 Maintenance of laser pickup
(1) Cleaning the pick up lens
Before you replace the pick up, please try to clean the lens
with a alcohol soaked cotton swab.
(2) Life of the laser diode
When the life of the laser diode has expired, the following
symptoms will appear.
• The level of RF output (EFM output:ampli tude of eye
pattern) will be low.
Is RF output
1.3 0.4Vp-p?
±
YES
O.K
(3) Semi-fixed resistor on the APC PC board
The semi-fixed resistor on the APC printed circuit board
which is attached to the pickup is used to adjust the laser
power.Since this adjustment should be performed to match
the characteristics of the whole optical block, do not touch
the semi-fixed resistor. If the laser power is lower than the
specified value,the laser diode is almost worn out, and the
laser pickup should be replaced. If the semi-fixed resistor
is adjusted while the pickup is functioning normally,the la-
ser pickup may be damaged due to excessive current.
TE
L 13942296513
www
1-26 (No.49838)
http://www.xiaoyu163.com
NO
Replace it.
x ao
y
. i
http://www.xiaoyu163.com
3.4 Replacement of laser pickup 8
Turn of the power switch and, disconnect the
power cord.
Replace the pickup with a normal one. (Refer
to "Pickup Removal" on the previous page)
Plug the power cord in, and turn the power 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.
Check the eye-pattern at RF test point.
Q Q
3 6 7 1 3
u163
.
2 9 9 4 2 8
Play a disc.
Finish.
1 5 0 5 8 2 9 9 4
m
co
9 9
2 8 9 9