Troubleshooting - BRAND Dispensette S Operating Manual

11 Troubleshooting

11 Troubleshooting
Problem
Piston sluggish or stuck
Filling not possible
Dispensing not possible
Discharge tube (with or without recircu-
lation valve) cannot be mounted suffi-
ciently
Air bubbles in the instrument
Dispensed volume too low
76
Operating manual
Possible cause
Crystal deposits
Contaminants
Volume adjusted to min-
imum setting
Filling valve stuck
Discharge valve stuck
Discharge valve is not
screwed in deeply
enough
Reagent with high vapor
pressure has been
drawn in too quickly
Valve screw connections
loose
The instrument has not
been primed
Filling tube is loose or
damaged
Valves not firmly con-
nected or damaged
Filling tube is loose or
damaged
Filling valve is loose or
damaged
Corrective action
Stop dispensing immediately.
Loosen piston with circular mo-
tion, but do not disassemble.
Perform cleaning (Cleaning, p. 70).
Set the desired volume (Dispens-
ing, p. 62).
Unscrew the filling valve from the
valve block and clean it. If the
valve ball is stuck, use a 200 µl
plastic tip to dislodge it (Dislodg-
ing a stick valve ball, p. 74). If nec-
essary, replace the filling valve.
Unscrew the discharge valve from
the valve block, clean it and re-
place if necessary. If the valve ball
is stuck, use a 200 µl plastic tip to
dislodge it.
Tighten the discharge valve with
the assembly tool until it meets
the stop so that the threads are no
longer visible.
Slowly draw in reagent.
Tighten the valves firmly with the
assembly tool.
Prime the instrument (Prim-
ing, p. 60).
Push the filling tube on firmly. If
necessary cut off approx. 1 cm of
tube at the upper end and re-con-
nect it or replace filling tube.
Perform cleaning (Cleaning, p. 70).
Tighten the valves using the as-
sembly tool.
Perform cleaning (Cleaning, p. 70).
Push the filling tube on firmly. If
necessary cut off approx. 1 cm of
tube at the upper end and re-con-
nect it or replace filling tube (Re-
placing discharge tube, p. 73).
Perform cleaning (Cleaning, p. 70).
Tighten the valves using the as-
sembly tool. If necessary, replace
filling valves.
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