Advertisement
IMPORTANT
5: CARD #5
Before embarking on this procedure, be sure that Cards # 3 and # 4
have been standardized according to the alignment procedure above,
or are in their original factory- aligned condition.
a)
Connect the oscillator to the OPTIMOD-TV's left input, high side to "+", low
side to
b)
Pull
Card # 3 halfway out and connect the AC VTVM to TP1. TP1 may be
readily
accessed
at
the
end
of
R323
closest
to
the
edge
of
the
board.
Reinsert Card # 3. Make sure that Card # 4 is also in its slot. ( If only one card
is
inserted, all gain control current will be diverted to the VCA's in that card,
reducing the gain 6dB below its correct value.)
c)
Remove Card # 5 from its slot. Referring to the Card # 5 Assembly Drawing
in Appendix J, remove IC508 from its socket and set it aside temporarily. ( This
defeats the gating function.) Then extend Card # 5.
d)
Set the oscillator frequency to lkHz; set its output level to produce - 15dBm
at Card # 3 TP1.
e)
Switch
the
Compressor
PROOF/OPERATE
switch ( on
Card # 5)
to
PROOF
and allow the gain to settle for at least one minute.
f)
While you are waiting, reconnect the AC VTVM to the output of IC307A on
Card # 3.
This
point
can be
readily
accessed
at
TP#K
or
pin
K on
the
edge
connector
by
pulling
the
card
halfway
out,
and
reinserting
it
as
above.
g)
Adjust R501 ( MASTER GAIN CAL) on Card # 5 until + 2.0dBm is observed on
the AC VTVM.
h)
Set the oscillator frequency to 35Hz. Be sure that the oscillator output level
is the same as it was at lkHz.
i)
Adjust
R525 ( BASS
GAIN
CAL)
on
Card # 5 until
the
AC
VTVM
reads
+2.0dBm.
j)
Remove Card # 5 from the extender. Replace IC508 in its socket on Card # 5,
carefully
verifying
that
the
end
marked
with
the
notch
is
at
the
end
of
the
socket marked with a square or small flag on the printed circuit foil. ( If there is
any
doubt,
check the Assembly Drawing
in Appendix .1.) If
the IC
is
inserted
backwards, it will be instantly destroyed on power- up!
k)
Restore Card # 5 to its slot.
6: CARD #6
This
card serves both left and right channels. The procedure below is performed
twice;
once
for
the
left
channel
and
once
for
the
right.
When
the
reference
designator
of
an
alignment
trimmer
is specified,
the
reference
designators
for
both left
and right
channel
trimmers will be
given
in
order, with the right
in
parentheses.
a)
Extend
Card # 6.
Place
both
PROOF/OPERATE
switches
in
PROOF.
Turn
R626 and R660 ( FET BIAS) fully clockwise to guarantee that the FET's in IC603
will be fully pinched- off.
b)
Connect the output of the tracking generator in the 5L4N spectrum analyzer
to the left ( right) audio input of OPTIMOD-TV.
E-4
Advertisement
