Service manual

PN 4237242C
2.3-4
INSTRUMENT DESCRIPTION
FLUIDICS PANEL
Solenoids provide the fluidic logic for the MD II. There are 12 fluidic solenoids mounted on
the Diluter Panel (Figure 2.3-2). Table 2.3-1 lists these solenoids, their name, type and
function.
Probe/Wipe Traverse Assembly
The Probe/Wipe Traverse Assembly is located on the upper front of the instrument
(Figure 2.3-1) and is responsible for presenting the probe for whole-blood aspiration,
washing the probe after aspiration, and moving whole blood and diluted sample to the
appropriate bath.
Vertical movement is provided by a small stepper motor, the probe motor, mounted to the
traverse housing. See Figure 2.3-3. Control is provided using two optical sensors mounted on
the Probe/Opto Sensor card.
As the probe is moved up and down, it travels through the wipe housing. The wipe housing
has two ports, one with high vacuum applied, another attached to the diluent syringe. After
aspiration, as the probe is moving up, fluid is forced through the housing by the diluent
syringe as vacuum is applied. This washes the probe exterior. At several other instances of
instrument operation, with the probe moving up or down, vacuum alone is applied to dry the
probe and ensure that no dripping occurs.
Horizontal movement is provided by the traverse motor, a larger stepper motor using a belt
drive. The entire probe and probe wipe mechanism is moved as a unit to each station. This
eliminates many alignments and adjustments, producing a simple and reliable mechanism.
The only adjustment on the assembly is the spring belt tensioner for the horizontal drive belt.
This tensioner is designed in such a way that it does not need readjustment even when the
belt is replaced.
Table 2.3-1 Diluter Panel Solenoids and Their Function
Solenoid Name Type Function
LV3 Vac Select 3-way Selects regulated or raw pump vacuum for the VIC.
LV4 Sweep Flow 2-way Opens the diluent path for sweep flow.
LV5 RBC Aper Vac 2-way Opens the RBC aperture count path to the VIC.
LV6 WBC Aper Vac 2-way Opens the WBC aperture count path to the VIC.
LV7 Bath Drain Sel 3-way Selects which bath drains.
LV8 PRB Wipe Vac 2-way Opens a path from the VIC to the probe wipe housing to evacuate fluids with
high vacuum.
LV10 Waste Select 3-way Selects whether one of the baths drains or the VIC drains.
LV11 Bath Rinse Sel 3-way Selects which bath receives rinse from PM3.
LV13 Prefill Select 3-way Selects which bath gets prefill from the diluent syringe.
LV14 Dil Prefil/Disp 3-way Selects whether diluent from the diluent syringe is used for prefill or the
dispense selection of LV16.
LV15 Dil Srng Fil 3-way Switches between the diluent reservoir for diluent syringe input and LV14
for diluent dispense output.
LV16 Dil Dispense 3-way Switches diluent dispense between the probe wipe housing and the aspirate
probe via the aspirate syringe.