5.Operation
5.7 Defrosting
The Leica CM3050 S has 3 (instruments without specimen cooling: 2) different defrosting options.
-Automatic chamber defrost cycle
-Manual chamber defrost cycle
-Specimen head defrosting (manual) - instru- ments with specimen cooling only.
Read the safety instructions in chap- ter 2.3.7 ‘Defrosting / frozen speci- mens’ !
Make sure to remove sensitive speci- mens from the cryochamber before the defrost cycle starts!
5.7.1 Automatic chamber defrost cycle
The automatic defrost cycle is carried out once every 24 hours at the preselected time.
(For details see chapter 5.3.4 ‘Menu functions’ - items 6 and 7).
During the defrost cycle, the corresponding as- terisk is displayed inversely:
C | T | - | 3 | 0 | ° | C |
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| O | T | - | 3 | 5 | ° | C |
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Once the defrost cycle is finished, the instrument automatically switches back to refrigeration.
Instruments with specimen cooling:
When defrosting starts, to avoid icing the speci- men head is automatically adjusted to a temper- ature between
The specimen head refrigeration is automatical- ly switched back on when:
•at least 4 hours have passed since the de- frost cycle was completed;
•and the actual chamber temperature devi- ates less than 5 K from set value.
After the specimen head refrigeration has been switched back on, the specimen head tempera- ture rises briefly to +10 °C and then decreases until it reaches the set value.
Switching specimen cooling back on immedi- ately after defrosting:
As soon as the chamber defrost cycle is com- pleted, specimen cooling can be switched back on immediately:
•Press 
until menu item ‘Set specimen temperature’ is displayed:
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Specimen cooling is switched back on.
Despite the possibility of switching the specimen cooling system back on immediately after the automatic chamber defrost cycle, we recom- mend the automatic defrost cycle be set at a point in time when the entire procedure can be controlled automatically.
(See also information on menu items 6 and 7 in chapter 5.3.4 ‘Menu functions’).
Leica CM 3050 S – Cryostat | 45 |
