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L- R does not null on mono material.
1.
This
is
caused
by
gain,
frequency
response,
or
phase
response
differences
between
the
left
and
right
channels.
So
before
assuming
that
the
problem
is
internal to OPTIMOD-TV, make sure that the feed is really 100% mono. This can
be reliably assured by driving both left and right OPTIMOD-TV inputs in parallel
from a single signal source.
2.
If
L- R will
not
null
in
PROOF
mode,
then
the
problem
is
static,
and
is
caused
by
abnormal
frequency
and/or
phase
response
in
one
channel.
If
the
frequency response is normal, suspect the phase correctors on Cards # 6, # 8, and
#9 ( including Al, the phase delay network module).
3.
If L-R will
null
in PROOF
mode,
then
the
left
and
right
VCA's
or
high
frequency limiter circuitry are failing to track dynamically under gain reduction
conditions. In the case of the VCA's, the dual gain block ( IC305, for example) is
suspect.
In
the
case
of
the
HF
limiter,
the
rectifiers
or
timing : nodules
are
suspect.
Sibilance Distortion.
1.
Source material at OP IIMOD-TV input terminals distorted.
2.
Failure in highpass filter on Cards # 8 or # 9.
3.
Failure of the HF limiter. If the HF limiter isn't working at all, then even a
properly- operating
distortion- cancelling
clipper
may
generate
some
audible
distortion.
FACTORY
Orban
Associates Inc.,
maintains
a Customer
Service
Department
to
help Orban
ASSISTANCE
product
users who experience
difficulties. Orban Customer Service
is
supplied at
two
levels.
The
first
is
telephone
consultation.
Often,
a problem
is
due
to
misunderstanding, or is relatively simple and can be fixed by the customer aided by
phone
advice from the factory. Telephone consultation should always be the first
step in
any factory service transaction. Units will be accepted for factory service
(the
second level) only after
consultation, and only after a Return Authorization
(RA) code number has been provided by phone or letter. The RA number flags the
returned unit for priority treatment when it arrives on our dock, and ties it to the
appropriate information file.
The
purpose of this formality is to save both the customer and the factory time
and
trouble by attempting
to weed out
problems which are caused by equipment
other
than
OPTIMOD-TV,
misapplication,
or
environment,
and
to
identify
those
problems that lend themselves to quick field repair.
Before
calling Customer Service, be
prepared to give the
model
number ( 8182A)
and
serial
number
of
your
unit.
If
the
unit
is
in
its
warranty
period
and
the
Registration Card was never returned, we will also need the name of the dealer
from
which
the
unit
was
bought,
the
invoice
number,
and
the
invoice
date.
Be
prepared to accurately describe the the problem. What
is the complaint? Is it
constant
or
intermittent?
If
it
is
intermittent,
can
it
be
correlated
to
environmental conditions like line voltage, temperature, humidity, electrical storms,
vibration, etc? Do problems only occur with certain program material ( live voice,
very
bright
music,
music
with
heavy
bass
transients,
etc.)?
What
about
source:
network,
VTR,
film
chain,
cart,
disk,
reel-to-reel
tape,
live
microphone?
Be
prepared
to
describe
any
unusual
observations
made
during
the
Problem
Localization Routine you performed using the instructions above.
F-9
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