Securitron DSB_Series - Manual (Page 11)

PN# 500-22700
Page 10 Rev. F, 03/11
Figure 15 shows the installation of an MOV in parallel with the magnetic lock. An MOV is
provided with each DSB. It is a black (or blue) disk-like component with two bare wires for
connection. The MOV acts to suppress the inductive kickback by a lock, which if left
unsuppressed will greatly shorten the life of the relay contacts. The MOV has no polarity, but in
order to function properly it should be spliced in to the wiring as close to the electric lock as
possible.
MOV
MAGNETIC
LOCK
+
_
Figure 15
IF A SECURITRON MAGNALOCK IS USED IN THE INSTALLATION, THE MOV IS NOT
NECESSARY AS THE MAGNALOCK IS ALREADY INTERNALLY SUPPRESSED.
THE POWER SUPPLY MUST ALWAYS CONNECT DIRECTLY TO THE MAIN DSB PC BOARD.
IN MAKING POWER CONNECTIONS ENSURE THAT PROPER POLARITY IS MAINTAINED.
The DSB operates on 12-24 Volts DC and is normally powered by the same power supply that
operates the lock. When connecting power to the unit, ensure that proper polarity is maintained.
As an additional safety feature, the DSB includes a low voltage sensing circuit. The unit will
keep working normally until input voltage declines to below roughly 9 Volts. At approximately
that point, the DSB automatically performs as if all power was removed (i.e. if a lock is being
controlled by the DSB, power to it will be cut and it will release).
8.2. DOUBLE BREAK WIRING
Many installations include a controlled access device such as a digital keypad or card reader.
Such devices typically have a REX (request to exit) input. When dry contacts close on this input,
the entry device will open the lock for the same amount of time that is programmed for entry.
Implementation of the REX input for exit can provide timed exiting. Also, for most entry
controls, the REX input must be used for exiting to avoid an alarm condition at the door.
If the REX input alone is used for exiting, a safety/reliability problem will exist. If the entry
device malfunctions, exit will not be possible and people may be trapped. It is recommended
that double break wiring which is supported by the DSB be used because of its two pole relay.
The DSB normally closed contacts are used to break power to the fail safe electric lock while the
normally open contacts trip the REX input of the controlled entry device. This releases the lock a
second time, hence the term, "double break". If the controlled entry device fails for any reason,
direct exit is still possible.
8.3. ADJUSTING TOUCH SENSITIVITY
After the wiring is completed the sensitivity of the touch sense must be adjusted. This can be
done at any time by removing the end mount cap from the main PC board end of the bar and
adjusting the potentiometer using a small flat tip (or Phillips) screwdriver (see Figure 16). The
potentiometer that controls the touch sense will increase sensitivity when turned clockwise and
decrease sensitivity when turned counterclockwise.
For initial setup, turn the pot clockwise without touching the bar with a small screwdriver until
you see the red LED illuminate. In this condition, sensitivity is set so high that the bar is
“sensing” or in release mode all of the time. Slowly rotate the pot counter-clockwise until the
LED goes off and then turn another 10 to 20 degrees counter-clockwise and stop. This is
generally a good initial setting. Before replacing the end cap, experiment by touching the bar
and observe that the touch sense LED goes on and off. Sensitivity can be increased somewhat,
but leaving the DSB set to just below the point of continuous release risks a condition of security
failure especially if the unit goes into a constant release mode.