ELGA PURELAB UHQ II & PS Service Manual
PURELAB UHQ II & PS Service issue 2 03/07
20
9.2
Level control calibration.
9.2.1 Remove right-hand and left-hand side covers from the unit.
9.2.2 Remove the four fixing screws holding the front cover to the framework. These
are accessible at the back corners of the front cover, having first removed the
two side covers.
9.2.3 Remove the retaining plug from underneath the Dispense Pen well; this is
situated underneath the front right-hand edge of the unit and is a grey-coloured
plug which is simply pulled from the tube it is pressed into.
9.2.4 Whilst standing at the front of the unit, rotate the front panel, about its left hand
vertical edge to expose the electronics compartment. Care should be taken to
ensure no strain is applied to the ribbon cables connecting the main control
PCB to the display PCB.
9.2.5 Carefully remove level control assembly from reservoir by unscrewing (anti-
clockwise). The cable terminates onto a PCB which is located inside the level
control assembly down tube and this can either be withdrawn from the down
tube or else it can be held steady by holding the cable cover whilst the tank
adaptor is unscrewed to prevent the cable twisting (see Fig 9.2 on next page).
9.2.6 Hold the level control assembly horizontally and check that the float moves
freely along the down tube.
9.2.7 Position the float 10 mm from down tube end cap. Check display read-out; it
should indicate 2 bars, if not, adjust Pot (P2).
9.2.8 Slowly move float towards end cap. The display should indicate 1 bar just
before the float reaches the end cap.
9.2.9 Move the float so that it is positioned 10 mm from the retaining circlip at the
adaptor end of the down tube. Check display read-out; it should indicate 17
bars, if not, adjust Pot (P3).
9.2.10 Slowly move float towards the retaining circlip. The display should indicate 18
bars just before the float reaches the retaining circlip.
9.2.11 Move the float over the full length of the down tube. Check volume display read-
out changes progressively.
9.2.12 Repeat instructions 9.2.9.to 9.2.11.
9.2.13 When the float is in contact with the down tube end cap, the display indicates 1
bar, and when the float is in contact with the adaptor end retaining circlip, the
display indicates 18 bars and the display changes uniformly as the float is
moved along the guide tube; the level controller is electronically functioning
correctly and is calibrated correctly.
Note: If movement of the float causes no change in the bar display, it could be either
a faulty float or a defective reed switch on the PCB. To ensure correct operation of the
level controller, the tank adaptor should be fitted correctly to the down tube, as per
dimensions given in the drawing on next page, from bottom of down tube to underneath
the tank adaptor. With this dimension correctly set, it will ensure that when the float
operates the upper reed switch, the maximum water level within the tank will be
approximately 5 mm from the inside edge of the top of the tank, i.e. will leave a 5 mm
air gap.
9.2.14 With the float resting on the down tube end cap, press REFILL button. Ensure
red REFILL LED is illuminated and the inlet solenoid is open.
9.2.15 Move the float along the down tube until all 18 bars of the volume display are
indicated, i.e. 100% reading. Ensure the inlet solenoid valve has closed and the
red fill light is extinguished.
9.2.16 With all the above conditions met and the level controller calibrated correctly,
turn the power off to the unit. Refit level controller float assembly into tank
ensuring level controller tank adaptor is screwed down flush with the top of the
