Avery Berkel CX20 SERIES, Руководство по обслуживанию

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2 — General and Technical
2–5 CX20/CX30/CX34 Service Manual
A transducer is mounted on the chassis. On top of this is positioned a four–arm,
cross assembly. The weighplate has four spigots on its lower surface, each of
which sits in a cross rubber at the end of each arm of the cross assembly. A
load placed on the weighplate is, therefore, transferred evenly through the cross
assembly to the transducer. The transducer physically distorts under the
influence of a load, and this distortion is detected by the strain–wires attached
inside the transducer.
Overload protection of the transducer is provided by an adjustable grub screw
fitted to the transducer mounting bracket directly underneath the transducer,
below the centre of the cross assembly. Additional adjustable bolts are provided
below the extreme end of each arm of the cross assembly to prevent
asymmetrically–placed loads from overloading the transducer. There are no
mechanical stops to prevent the occurrence of an excess negative load.
A printed circuit board (PCB) containing the power supply components is
attached to the chassis: the power supply is a switch mode power supply
(SMPS). This assembly is covered by a metal shroud fabricated from sheet
aluminium. The shroud is ventilated by a series of slots around the upper area
of its sides.
A main PCB containing the majority of the electronic components of the unit is
positioned over the chassis and below the cross assembly. A rectangular hole
near the middle of the main PCB provides clearance for the transducer
mounting block onto which the cross assembly is secured.
The main PCB is positioned above the chassis on four pillars, one at each
corner: two pillars are attached to the chassis and two to the printer spine. Two
clamps, each spanning two pillars and held in position by two special nuts,
clamp the main PCB to the top of the pillars. The top surface of the pillars is
where the adjustable bolts are installed which act as asymmetric overload stops
for the transducer.
A secondary PCB, the analogue–to–digital converter (A/D PCB), is installed on
the component side (underside) of the main PCB. This is located by four plastic
pillar clips spanning between the A/D PCB and the main PCB, and by the
electrical plug interface.
A communications controller (comms) PCB is available as an optional addition
and is fitted on the component side of the main PCB. This is located by four
plastic pillar clips and is connected to the main PCB by a flying ribbon cable
from the comms PCB.
For descriptions of the transducer, keyboard, displays, printers, main PCB and
comms PCB, refer to the appropriate sections in this manual.