INFICON STC-2000A Thin Film Deposition Controller Operating Manual - Manual (Page 275)

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STC-2000A DEPOSITION CONTROLLER
y
2000A should read about 50% while this button is depressed. If this is observed while this button is
depressed the problem of the persistent bad crystal indication has been isolated to be in the path between
the remote oscillator and the sensing crystal. If the bad crystal indication continues while this button is
depressed, then the failure is: in the programming of the sensor selection, in the electronics of the remote
oscillator, in the STC-2000A unit itself or in the connecting cable. This push-button can be activated by
inserting a small rod or wire, like a straightened paper clip in the 'push to test' hole and depressing the
switch.
Figure 8.1: Sensor and Feedthrough Connections.
OSC-100A OSCILLATOR
Push to Test
Serial No.
4571
instruments
East Syracuse, NY
Figure 8.2: Test Oscillator OSC-100A.
The fastest and easiest way to check for a good connection path between the Remote Oscillator
and the sensing crystal is to measure the electrical resistance of the cables with a Ohm meter capable of
reading 0.10
Ω. Remove the oscillator from the 6" BNC cable, and remove the sensor cover and sensing
crystal from the sensing head. Measure the resistance from one of the center push spring contacts inside
the sensor unit to the center conductor of the cable normally connected to the oscillator. The reading
should be less than 0.20
Ω. The center conductor to the cable shield should be open (greater than 30 MΩ)
with respect to the outside ground shield of the cable. This check will verify all the connections from the
sensor, the InVac cable, the vacuum feedthrough, and the BNC cable.
Figure 8.3: SM75, MicroDot
®
Connector.
If the reading from the continuity test is not as stated, disconnect one part of the chain and repeat
the test. Repeat this last step until the bad connection is isolated. From experience, most often, when a
problem occurs it has been found that the SM75, MicroDot
®
, connectors on the InVac cable are not
connected securely to the sensor or the feed through. If this is found to be true then the cable should be
replaced. Also the center pin on the InVac cable can become damaged and not make contact with the
mating connector, Refer to Figure 32.14. The center pin of the connector should extend slightly beyond the
end of threaded ferrule. If the pin is damaged the cable should be replaced.
SECTION 8.XX page 275 of 292