INFICON TM-400 Thin Film Deposition Monitor - Manual (Page 52)

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TM-350/400 Operating Manual
Correcting the cause of the failure then pressing the Stop key clears a crystal
failure.
A crystal that has failed should be replaced. For obvious reasons crystals should
normally be replaced well before they are likely to fail. See
Chapter 6 for the
procedure on replacing failed crystals.
7.7 Power Fail Indication
The Monitor is designed to tolerate short duration power failures of less than 250
milliseconds. During a deposition, if the power is disrupted for less than 250
milliseconds, there is no disruption to the deposition. However, if the power is
disrupted for more than 250 milliseconds, the deposit is terminated. And, because
the Monitor is designed for possible unattended operation it does not reopen the
source shutter if the power returns a process disruption of this duration could
seriously affect the deposition. Instead the Monitor retains the value of the film
thickness at the time of power failure and flashes the "P FAIL" message to indicate
to the operator that power was down during their absence. The operator then has
the option of continuing the deposition if desired by restarting the Monitor.
7.8 DAC Operation
The monitor has one rate and one thickness DAC output, which are suitable for
recording with a strip chart recorder or other recording device. Each DAC has a
selectable range which is used to convert the appropriate display to a 0 to 5-volt
analog signal. The four available DAC ranges are selected by setting the S16
dipswitch array on the TM's front panel PWB. The default setting is 99 for both
DAC's. To select a different range, unplug the TM, remove the top cover and
change the settings. The new settings will take affect once the TM is turned on. The
S16 DIP switch array also controls other features of the TM as listed in
Table 7-1 .
Table 7-1 S16 DIP Switch Features
Switch # Description
1 DAC Rate Range Select Bit 0
2 DAC Thickness Range Select Bit 0
3 Disable negatives - Disables negative rate and thickness values
4 Switch to backup crystal even if backup is failed
5 DAC Rate Range Select Bit 1
6 DAC Thickness Range Select Bit 1
7 Allows source shutter to pulse close (on) for 1 sec. once thickness endpoint
is reached.
8 Disable Sensor #2