Securitron TSB-3 - Manual (Page 8)

PN# 500-16400
Page 8
Rev. C, 11/07
proximity of ionized fluids within the body, which form a conductive mass. It is this mass that the bar
detects. As a proximity device the bar is sensitive to the closeness of the mass. For example, if a person
wearing gloves touches the bar with his finger tip, the door will generally not release. When the gloved
hand is wrapped around the bar in normal use, the door will release because the conductive mass of the
hand is in much closer contact with the bar.
The main security concern regarding outside entry is if a person could introduce a metal wire from the
outside and make metal to metal contact with the bar. The field could then propagate along the wire and
be activated by the intruder's hand. In practice, this is unlikely. The bar is anodized and therefore
insulated so it will not make contact with the wire. The intruder would have to scratch away the
anodization which requires both effort and knowledge. Also the field propagates weakly along a thin wire.
If, however, high security from the outside is critical in the application, two steps should be taken. First,
the sensitivity of the bar should be set as low as satisfies the exit performance requirements. Second, the
insulation on the bar should be increased by painting it. This significantly increases resistance to
scratching. Electrostatic (powder coat) paint is recommended for greatest toughness.
6. SENSOR REPLACEMENT
A: Remove the end cap on the sensor side. Remove the cable connector from the circuit board.
B. Remove the two screws that connect the end piece to the aluminum bar. Note that this will free the
ring terminal that is soldered into the board on the pad marked, "bar". This ring terminal is the way the
sensor makes contact with the bar. Slide the complete end piece out of the bar.
C: With the end piece now loose in your hand, push the circuit board farther into the end piece. The
direction is as if you were pushing it into the bar. There will be some resistance from the wires that
connect the backup switch to the circuit board. Push it only far enough to completely reveal the
rectangular body of the backup switch.
D: Unscrew the plastic retaining ring that holds the backup switch to the end piece. Push up the freed
backup switch. Now the complete sensor + backup switch can be slid away from the end piece by
continuing to slide the board in the same direction.
E: To install the new sensor assembly, reverse the procedure detailed above. But note that the wires that
connect the backup push button to the circuit board must be folded over in the center of the board- inside
of the potentiometer. If the wires are allowed to fold outside the potentiometer, they will block access to
it and the board will not be able to slide fully forward.