5TAR~IECff.JOURNAL.___E__
_ _ J_u_NE_1s_a_4 _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
it was locked in place properly (they
won't easily freeze up, so if it
doesn't move I assume the screw is
there) and I proceed to pull up the
circuit board for inspection. If there
is a lot of dirt or oily film in the unit, I
will also open the slider itself before
energizing the unit. This allows
inspection of the laser ballast
resistor and its glass casing, to
inspect for signs of overheating
(blackened appearance). If I see
B
this, I will not try to fire the laser
until I've tested the high-voltage
power supply. If the ballast resistor
was discolored, I replace it and
expect that the laser tube will not
be short-lived. (Pioneer rates the
PR821 0 laser tube conservatively
at 2500 hours, and the 7820 laser
tube at 3500 hours).
paper and cleaning solution, just
as on the objective lens, but the
canned aerosol seems to work well,
and has caused no problems so far.
If you do open the slider for inspec-
tion, you may as well clean it while
you're there, since smoke film
always seems to find its way to
these optics.
Lately we've been using canned
aerosol Freon TF to clean the slider
optics. Previously we used lens
All the above may seem like lots of
extra work to learn a few things that
could be observed faster by just
firing up the player, but laserdisc
player parts are very expensive,
and the backorder time can be
lengthy. Also, by consistently fol·
lowing these steps, I have eliminated
some very common problems. For
instance, you will spend hours
troubleshooting before you find
dirty optics in the slider(unless you
are intimately familiar with the
photo-diode arrangement), or sus-
pecting a focus problem when
actually the cause is a broken pinion
gear, or trying to adjust a tracking
problem actually caused by sticky
slider rails. The investment made in
inspecting the units always pays
off.