Maintenance Of Laser Pickup; Replacement Of Laser Pickup - JVC UX-M3R Service Manual

UX-M3R

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 below.
Is the level of
RF OUT under
1.25V 0.22Vp-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 would be adjusted when the pickup operates normally,the laser pickup may be damaged
due to excessive current.
1-18

Replacement of laser pickup

Turn off the power switch and,disconnect the
power cord from the AC OUTLET.
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
NO
up and down.
Replace it.
Note: Do not observe the laser beam directly.
Replace the pickup with a normal one.(Refer
to "Removing the CD pickup" on the previous page)
Play a disc.
Check the eye-pattern at the "RF" test point.
Finish.