Troubleshooting
1C Opamps
1C opamps are usually operated such
that the
characteristics
of
their
associated
circuits are
essentially independent of
1C characteristics and
dependent only on
external feedback
components. The feedback
forces the voltage
at the (-) input
terminal to be
extremely close to the voltage
at the
(+)
input terminal.
Therefore,
if the technician
measures more than
a
few
millivolts between these two
terminals,
the
1C is probably bad.
Exceptions are
IC's used without feedback
(as comparators)
and IC's
whose outputs
have
been saturated due to excessive
input voltage because
of a defect in
an
earlier stage. Also,
be sure that the voltmeter
is not interacting
with these
sensitive
points
and
affecting
the measured voltage.
However, if an IC's
(+)
input is
more
positive than
its (-) input,
yet the output
of the
1C is sitting
at
-14
volts,
this
almost
certainly indicates
that it is bad.
The
same holds if
the above
polarities
are reversed.
A
defective
opamp may appear
to work,
yet it may have
extreme
temperature
sensitivity. If
parameters appear
to drift
excessively,
freeze-spray
may aid in
diagnosing
the
problem. Freeze-spray
is also
invaluable
in tracking
down
intermittent
problems. But,
use
sparingly
,
because
it
can
cause
resistive
short
circuits
due
to moisture
condensation on
cold
surfaces.
Factory
Service
Please
refer
to the terms
of
your
Orban
Associates
Limited
One-Year
Standard
Warranty
,
which
extends
to the first end-user.
This
warranty
was packed
separately
from the 622
and is
not bound with
this manual.
After
expiration
of the warranty,
a reasonable
charge
will
be made for parts,
labor, and packing
if you
choose to
use
the
factory
service facility. Repaired
units will
be returned
C.O.D.
In
all cases,
transportation
charges (which
are usually quite
nominal)
shall
be borne by
the
customer.
Ordering
Parts From
the Factory:
If
parts
are ordered
from
the
factory, we
require all of
the following
information:
—
The
Orban
part number,
if ascertainable from
the
Parts List
—
The
Reference
Designator
(e.g.
R503)
—
A
brief description
of
the
part
--
And,
from
the serial
label on the
rear of the
unit
-
the exact
Model Number
-
the Serial
Number
-
The
"M" number,
if any
Returning
the 622
to the Factory: After
a formal
Return
Authorization
number is
obtained
from the
factory,
units
should be shipped
to CUSTOMER
SERVICE
at the
address shown
on the
front
page of this manual.
YOUR
RETURN
AUTHORIZATION
NUMBER
MUST
BE SHOWN
ON THE
LABEL,
OR
THE
PACKAGE
WILL NOT
BE
ACCEPTED!
PHONE
(415)
957-1067
OR
TELEX
17-1480
Shipping
Instructions
If
the original
packing
material is available,
it should
be
used. Otherwise,
a carton
of
at least
200
pounds bursting
test and
no smaller
than
22"
x
10"
x
10"
should
be
employed.
18
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