Leica CM1950 Projection Television User Manual


 
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Leica CM1950 Cryostat
8. Working with the Instrument
Programming the defrost cycle
Set the beginning of the automatic defrost cycle.
The automatic defrost cycle takes place once within 24 hours.
It is set with the "+"/"-" buttons on the right of the panel with the clock
symbol. The two buttons are marked by a melting snowflake
.
Briefly press the "+" or "-" button for indication of the beginning of the
defrost cycle which has actually been set. At the same time, the LEDs
between the indication of hours and minutes are flashing.
To change the beginning of the defrost cycle in steps of 15 minutes, push
the "+" or "-" key. When the "+" or "-" button is pushed for more than 1 s,
the defrost time value increases or decreases continuously.
Before starting the defrost cycle remove all samples from the
cryochamber!
When the automatic defrost cycle begins, the specimen head tempera-
ture adjusts to a temperature between - 10°C and - 5°C (reduction of ice
formation). The specimen head cooling turns off. This is confirmed by the
flashing of the decimal points on the panel for the specimen cooling. The
specimen cooling (controlled to set value) automatically turns back on
after 4 hours, once the chamber temperature varies by less than 5 K from
the target temperature.
If you want to turn the specimen cooling back on manually before the
automatic activation sets in, push the "+" or "-" button on the panel for the
specimen cooling and then the key button.
The temperature of the specimen cooling first raises to +10 °C and then
adjusts to the programmed specimen temperature.
Manual defrost for the freeze shelf (including Peltier element)
Press the key for manual defrost
,
then the
key.
The manual defrost takes 12 min.
Push the button and then the
key again to stop the manual defrost.
After defrosting the freeze shelf, carefully wipe it out, as otherwise
a lot of water collects in the channel. Ice does not melt during
normal defrosting.