Chemglass AF-0304 - Manual (Page 21)

5. TECHNICAL DATA
5.2. Gauge Tube Wiring
It is strongly recommended that every customer keep a
small stock of spare gauge tubes on hand along with a
Reference Gauge Tube Calibrator.
Always try a new tube before considering circuit failures.
The Reference Gauge Tube Calibrator may be connected
to the circuit to prove whether the problem is a gauge
tube or circuit failure. If the instrument works properly with
the Reference Gauge Tube Calibrator circuit, then gauge
tube failure is a certainty.
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5.1. Troubleshooting
The gauge tube can be checked with an ohmmeter
between pins 1 and 5 to verify that the sensor is good.
Generally, the reading is less than 2.5 ohms if good; 900
ohms if the sensor is broken.
The actual readings for each type of tube should be as
follows:
SENSOR PINS 1 TO 5 HEATER
BLACK AND GREEN WIRE WHITE AND
APPROXIMATE RESISTANCE RED WIRES
100 mT 2.4 Ohms Pin 6 To 8
2000 mT 2.1 Ohms Pin 4 To 8
20 Torr 1.3 Ohms Pin 3 To 8