Western Instruments WC Series Operating instructions

Western Instruments Yoke WC-42 - Power Cord Trouble Shooting
WC-Series Yokes use the Omron B3F Series switch. These switches have a ground
provision, are designed for rugged use, and are sealed. Additionally, these switches
conduct less than ½ Watt of power, and are connected to our solid state switching
module. WC switches are therefore unlikely to fail. There is, however, the chance
that an electrical overload or mechanical damage may occur. These instructions can
be used for all manufactured products that use the Omron B3F series switch.
1. Remove the switch cover. WC series yoke switch covers are glued in
position to create a water resistant seal. Prying the switch cover off will
damage the material, but it is prudent to replace the switch cover when
repairing the switch.
Using whatever tools at your disposal, the old switch cover must be
removed, without damaging the switch cavity or the cast in Cover Seat
that the switch cover sits on. Furthermore, it is better to remove the old
glue as well.
Note: If the underside of the switch cover is burned, it is a telltale sign that
the yoke has been connected to 110 volts DC. This power is found on old
engine driven portable welders and some merchant ships.
2. Using a pair of tweezers or small pliers, gently lift the switch up out of the
cavity without damaging the 3 wires that are soldered to it. Note the
positions of the wires on the switch. When replacing the switch, the wires
must be soldered in the same positions. Refer to Testing WC-Series
Frame write up for the identification of wires on the Junction Tubes
Connector.
3. Using the tweezers or pliers, hold the switch, then apply heat with your
soldering iron. The switch is then easily removed and the switch wires are
pre-tinned. Take care not to touch the encapsulant with the soldering iron.
4. Examine the switch cavity. Note any burns that would indicate a use of
DC voltage.
WC-Series
Switch Cavity
Switch Cover Seat
Ground Wire
2nd Connector on Junction
Tube Connector (Common)
3rd Connector on
Junction Tube
Connector (Live)
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5. Using a small brush, clean the switch cavity with electrical contact cleaner.
Using the area inside the Junction Tube of the Yoke, test to ensure your
contact cleaner does not affect the Urethane Encapsulant. If chemicals at
your disposal are limited, first clean the cavity with 100% Stoddard Solvent
(paint thinner), followed by 99% Isopropanol (Isopropyl alcohol).
6. Prepare the replacement Omron B3F series switch. The B3F is
manufactured for PCB mount, so the 4 leads must be reshaped for use on
the W-series products. Bend the leads to a 45 degree angle upward.
Remove the 2 locating tabs on the underside of the housing. This will help
the switch to lie flat in the bottom of the switch cavity.
7. Pre-solder the leads and ground on the switch . Only 2 leads need
soldering. The ground solder is applied to the top of the switch. See the
picture below.
8. Carefully establish which wire is the ground wire. If you were unable to
take note of this when removing the damaged switch, use a continuity
tester by placing one lead at the end of one of the wires, and the other
lead on the ground lug or junction tube.
9. Solder the two switch wires to the 2 soldered leads and the ground wire to
the top of the switch. Take care not to touch the encapsulant with your
soldering iron.
Note: The switch has 4 solder leads, but only two are used. Ensure that
the 2 leads that are used are diagonal to each other.
10.Position the newly soldered switch in the switch cavity, ensuring that the
switch wire insulation is not pressed up against the leads. This may cause
the insulation to be cut.
11.Care must also be taken to ensure that the switch wires do not protrude
up above the seat to which the switch cover is affixed. If the wires are too
high, they will be subject to wear during the operation of the switch. The
repeated depression of the switch cover to operate the yoke may cause
the wires to move, and eventually erode and disengage.
12.Once the switch is in position, press firmly on it so that it lies flat on the
bottom of the switch cavity.
Ground Wire 2n
d
Connector on
Junction Tube
Connector (Common)
3r
d
Connector on
Junction Tube
Connector (Live)

Note: Push all the switch solder leads into the wall of the switch cavity to
secure the position of the switch.
13.Test the switch again using the continuity tester. Place the leads from you
meter in the middle two connectors of the 4 pin module connector located
in the junction tube. When the switch is pressed you should have
continuity.
14.Clean the new switch cover using the chemicals used to clean the switch
cavity.
15.Run a thin bead of Gap Filling Cyano-Acrylate Glue around the Seat for
the switch cover. Reinsert the switch cover, and apply pressure for the
time specified by the manufacturer. Ensure that the cover is glued
continuously around the Seat. A water-resistant seal is required.
Note: Fabricating a tube out of a nonstick plastic, slightly smaller in
diameter than the switch cover, will help in applying pressure where
needed while the glue is setting. Applying pressure to the entire
switch cover may cause the switch to stick in the on position.
Note: Do not use an excessive amount of glue, as you don’t want it to
flow down into the switch cavity. To much glue may case the
switch to glue into the on position. Avoid gluing the Switch cover to
the sides of the switch cavity, as will make future repairs difficult.
Switch Installed Applying glue
carefully on
switch cover
Seat
Distributed by: ABQ Industrial LP USA
Tel: [phone] eFax: [phone]
Web: https://www.abqindustrial.net E-mail: [email protected]
Distributed by: ABQ Industrial LP USA
Tel: [phone] eFax: [phone]
Web: https://www.abqindustrial.net E-mail: [email protected]