INFICON STM-100/MF Thin Film Deposition Monitor - Manual (Page 74)

3. Verify that the newly installed crystal is operating by looking at the
STM-100 / MF "CRYSTAL FAIL" indicator legend. The flashing legend
should not be present. If the "CRYSTAL FAIL" legend is present check
for damaged cables, a cracked or broken crystal, or dirty contact surfaces
in the sensor cap.
Persistent Crystal Fail Indication
If you replaced the sensing crystal and the BAD CRYSTAL indication
persists, the problem is most probably somewhere in the electrical
connections. There exist approximately 12 mechanical electrical connections
between the sensing crystal and the oscillator unit.
Figure 6.1: Sensor and Feed Through Connections.
Remote oscillators shipped after Sept. 1992 have a test feature to help
isolate this type of problem, refer to Figure 6.2. A test push-button is provided
on the oscillator. This button connects an internal test crystal located inside
the remote oscillator in place of the normal sensing head. If the STM-100/MF
and remote oscillator are functioning correctly the XTAL FAIL indicator will go
away 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 either the programming of the sensor selection or in the
electronics of the remote oscillator of the STM-100/MF unit itself. This push-
button can be activated by inserting a small rod or wire, like an unbent paper
clip in the 'push to test' hole and depressing the switch.
OSC-100A OSCILLATOR
Push to Test
Serial No.
4571
instruments
East Syracuse, NY
Figure 6.2: Test Oscillator OSC-100A.
The fastest and easiest way to check for good connectivity is to Ohm out
the cable with a Ohm meter capable of reading 0.10
Ω. Remove the oscillator
SECTION 6.3
Page 6 - 3 MAINTENANCE