JEWELL 781, User Manual

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B-88-1006, REV. B 7
OUT -2
The signal carried on this terminal position is the OUT +2
signal multiplied by -1. OUT +2 is referenced to OUT -2
when a differential output is desired.
TEMP
This is the temperature output signal. It is a single-ended
signal, and is referenced to SIG GND.
SIG GND
This is the reference ground for the single-ended outputs
of the SCU.
ESD GND
This is a separate earth ground used for protection of the
internal SCU circuitry from high-voltage surges. ESD GND
is connected to the internal circuitry by transient surge
absorbers. These absorbers are nonlinear resistors that
change resistance as a function of the applied voltage
(the higher the voltage, the lower their resistance). Their
response time is approximately 50 nanoseconds. For
maximum surge protection, ESD GND should be
connected to an earthed pipe or ground rod.
+12 V
C11 to +15 volts DC to this terminal.
PWR GND
Connect the power ground (power common) to this
terminal
-12 V
Connect -11 to -15 volts DC to this terminal.
3.0 MAINTENANCE AND TROUBLESHOOTING
3.1 Routine Maintenance:
The SCU is rugged and should require no maintenance other than occasional cleaning of the
box with a soft cloth. Keep the SCU and tilt sensor from extremes of heat and cold. Extreme
temperatures unnecessarily stress the electronic components. If possible, keep the SCU and
sensors out of direct sun, because internal temperatures can build up to a level considerably
greater than the ambient temperature.
The SCU is protected from dust and splashes by its rugged aluminum enclosure. The unit is
not waterproof, so never allow it to be submerged, or allow standing water to accumulate inside.
NOTE: WATER DAMAGE TO INTERNAL COMPONENTS VOIDS THE WARRANTY!
Apart from the procedures described below, the SCU is not field-serviceable. Therefore, if you
should encounter problems not described herein, please contact a Jewell Instruments sales
representative at (603) 669-6400 for assistance.