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CAUTION: The A3 Controller PWB contains
static-sensitive devices. Take appropriate static
control precautions during handling and ser-
vice.
Reinstallation is the reverse process. Most of the
connectors are keyed to ensure correct orienta-
tion. The dc power connector P2 should be
installed with the ramps away from the PWB sur-
face, and the two TO-220 harnesses should be
installed with the raised tabs pointed away from
the Top Cover surface. If A3 is being installed
temporarily, install and tighten the bottom center
screws and the top righthand screw to ensure
ground integrity. Otherwise install and tighten all
six mounting screws before installing the Shield.
Set A3S1 to RUN and secure the Top Cover
before returning the unit to service.
5.2.5 A2 Display PWB
To remove the A2 Display PWB assembly, first
remove the Power Control Knobs by unsnapping
the knob caps, loosening the collet nuts and
pulling the knobs free of the encoder shafts.
Remove encoder bushing nuts using a 7/16''
(11mm) socket. Set the flat washers aside with
the nuts to prevent mixing them up with the
spacer washers behind the panel.
With the Top Cover open and Shield removed,
remove the four A2 PWB mounting screws. Pull
the PWB away from the Control Panel until the
encoder shafts are free, taking care to avoid drop-
ping the encoder spacer washers in to the unit.
Set these washers aside and separate from the
outer flat washers.
With a sheet of insulating material placed behind
the A2 PWB to prevent shorts, the unit may be
powered up with the component side of A2 visi-
ble for troubleshooting. Complete removal of A2
requires disconnecting the ribbon cable from the
A3 PWB, the flexcircuit connector to the Control
Panel and the dc power harness. Avoid unneces-
sary stress on the Control Panel flexcircuit.
CAUTION: The A2 Display PWB contains
static-sensitive components. Take appropriate
static control precautions during handling and
service.
5-4
Installation is the reverse process. Place spacer
washers on the encoder bushings prior to mount-
ing on the Control Panel; these washers are thick-
er than the flat washers used under the encoder
bushing nuts. Install and tighten the four PWB
mounting screws, then install the encoder flat-
washers and tighten the encoder bushing nuts.
The Power Control knobs may be installed in any
rotational orientation with respect to the encoder
shafts. Allow a slight clearance between the knob
skirts and control panel to provide free rotation.
Tighten collet nuts adequately to prevent acciden-
tal removal, then snap the knob caps back in
place. If colored caps are supplied, the yellow cap
should be placed on the Cut knob. Reinstall the
shield, set A3S1 to RUN and secure the Top
Cover before returning the unit to Service.
5.2.6 A1 Control Panel
The A1 Control Panel need not be removed
unless it is damaged or the membrane switches
malfunction. Reinstallation requires replacement
of the adhesive gasket which seals the panel to the
Top Cover.
To remove the A1 Control Panel, first remove the
A2 PWB. Remove the six remaining mounting
nuts. Remove the flat washer and Control Panel
shield layer grounds trap from the stud.
Working from inside the Top Cover, use a broad
screwdriver or similar tool to break the gasket free
from the Top Cover. Avoid deforming or gouging
the Top Cover to ensure a watertight seal when
the gasket is replaced. Remove the Control Panel
and gasket as a unit. Remove all residue of old
gasket material from the inside surface of the
Top Cover. Clean the mating surface with iso-
propyl alcohol and dry thoroughly before
installing the new gasket.
Inspect the new gasket to determine the side
which faces the Top Cover; the holes fit over the
Top Cover studs, and the pattern is not symmetri-
cal. Carefully remove the release paper from the
side of the gasket facing the Top Cover; do not
touch the adhesive. Slip the gasket over the eight
mounting studs. Neatly align the inside edge of
the gasket with the edge of the Control Panel
cutout in the Top Cover. With the gasket aligned,
press it in place using moderate, even pressure to
avoid bulges.
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Table of Contents
Troubleshooting
