Orban OPTIMOD-FM 8700, Operating Manual

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TROUBLESHOOTING ORBAN MODEL 8700i
G) Uncheck the “Use default gateway on remote network” box.
H) Select “OK.”
If this “Use default gateway on remote network” box is not selected, the
gateway will not point to the 8700i unit when you establish a direct or
modem connection.
Troubleshooting IC Opamps
IC opamps are operated such that the characteristics of their associated circuits are
essentially independent of IC characteristics and dependent only on external feed-
back components. The feedback forces the voltage at the (–) input terminal to be
extremely close to the voltage at the (+) input terminal. Therefore, if you measure
more than a few millivolts difference between these two terminals, the IC is proba-
bly bad.
Exceptions are opamps used without feedback (as comparators) and opamps with
outputs that have been saturated due to excessive input voltage because of a defect
in an earlier stage. However, if an opamp's (+) input is more positive than its (–) in-
put, yet the output of the IC is sitting at –14 volts, the IC is almost certainly bad.
The same holds true if the above polarities are reversed. Because the characteristics
of the 8700i's circuitry are essentially independent of IC opamp characteristics, an
opamp can usually be replaced without recalibration.
A defective opamp may appear to work, yet have extreme temperature sensitivity. If
parameters appear to drift excessively, freeze-spray may aid in diagnosing the prob-
lem. Freeze-spray is also invaluable in tracking down intermittent problems. But
use
it sparingly, because it can cause resistive short circuits due to moisture condensation
on cold surfaces.
Technical Support
If you require technical support, contact Orban customer service using the infor-
mation found at
http://www.orban.com/contact/ . Be prepared to describe the prob-
lem accurately. Know the serial number of your 8700i

this is printed on the rear
panel of the unit.
Please check Orban’s website, www.orban.com , for Frequently Asked Questions and
other technical tips about 8700i that we may post from time to time. Manuals (in
.pdf form) and 8700i software upgrades will be posted there too—click “Down-
loads” from the home page.
Factory Service
Before you return a product to the factory for service, refer to this manual. Make
sure you have correctly followed installation steps and operation procedures. If you