Maintenance Of Laser Pickup; Replacement Of Laser Pickup - JVC MX-G500 Service Manual

MX-G500

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.
(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 laser pickup may be damaged
due to excessive current.

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 "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 3seconds and the objective lens moves
up and down.
Note: Do not observe the laser beam directly.
Play a disc.
Check the eye-pattern at TP1.
1-24
Finish.
(2) 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 :
amplitude of eye pattern) will below.
Is the level of
RF OUT under
1.1V 0.2Vp-p?
YES
O.K
NO
Replace it.