99133R Cooling System Inlet One-
way Check Valve Replacement
Instruction:
1. Turn off the power and unplug the instru-
ment.
2. Remove the screws securing the instru-
ment cover, and remove the cover (see
below):
The following instructions refer to 4D3
cryoscopes without a suffix:
a. Remove the heat transfer fluid from
the front cover.
b. Remove the two screws from the rear
panel of the back cover and lift off the
back cover.
c. Remove the four screws from under-
neath the front cover, lift the front
cover slightly up, and then slide it for-
ward and off.
The following instructions refer to 4D3
cryoscopes with suffix "A" or later,
and to all 3D3 osmometers:
a. Remove the two sets of screws from
the side panels and the two screws
from the rear panel.
b. Slide the instrument cover up and off.
The following instructions refer to
4250 cryoscopes and 3250 osmometers:
a. Remove the two sets of screws from
the side panels and the four screws
from the rear panel.
b. Lift and tilt the cover so that the rec-
tangular opening clears the front of
the head cover first, then move the
instrument cover back, up and off.
3. If present, remove and save the screw
holding the cable clamp (B or F) to the
cooling system shroud (see Figure 2 or
Figure 5). Firmly gripping the pump
assembly outlet tube, remove the check
valve.
4. If needed, slip the new cable clamp onto
the pump assembly outlet tube.
5. Firmly grip the cooling assembly inlet
tube and remove the check valve.
Discard the old check valve and cable
clamp.
6. Install the new check valve, making sure
to orient the check valve properly (see
Figure 4). Connect the new check valve
to the cooling system inlet tube, then fas-
ten the new cable clamp using the hard-
ware saved in step 3.
On instruments shipped prior to 1996, the
cooling assembly inlet tube was a much
4DP690 Rev2
(4D35/3255/MK05 Service Manual)
Page 6 of 7
Figure 7
Fluid Filter
Fluid
Flow
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