Thermo Scientific 7450, Operating And Maintenance Manual

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The freezer responds to an open Sample thermocouple in different ways,
depending on what the unit is doing at the time or which freezing profile
has been selected.
1. Idle Mode - If the probe fails or is removed by the operator during
sample loading, while unit is in Idle Mode:
• Alarm LED lights (no audible alarm),
• LCD Display shows “S sensor fail” on the fourth line,
• Sample numeric display shows “ILL”.
The operator may start a run that does not reference the Sample
temperature, if the Sample probe is removed or open, and the Alarm LED
and the fourth line LCD message are cleared using the Silence key. The
run will proceed normally.
If the operator attempts to start a run using the Sample temperature for a
trip point,
• Audible alarm sounds,
• Run start prevented,
• LCD Display shows “S sensor fail” on the fourth line, alternated with
“S sensor req.”
The Alarm LED and display messages remain active until the probe
condition is resolved.
2. Run Mode - If the Sample probe fails during Run Mode, and the
current profile uses the Sample temperature as a trip point:
• Alarm LED lights,
• Audible alarm sounds continuously,
• LCD Display shows “S sensor fail” on the fourth line, alternated
with “S sensor req.”,
• Sample numeric display shows “ILL”,
• Immediately switches to Idle Mode,
• Disables all control functions.
Pressing the Silence key will mute the audible alarm, however, the Alarm
LED and display message will remain active until the probe condition is
resolved.
7007452 CryoMed Freezer 2-13 Thermo Scientific
Section 2
Set-Up and Operation
Sample Thermocouple
Open