3M 724 Instructions Manual - Audible Alarm Tones
7
Audible Alarm Tones
For wrist strap malfunctions the
Model 724 monitor indicates a
different tone for each operator-a
continuous tone for #1 operator and a
fast chirping beep for #2 operator. The
volume of the wrist strap alarm is
adjusted by selection of the internal
DIP switch #1. For work surface
malfunctions, a slow chirping beep is
made. This alarm sound is turned on
or off by selection of DIP switch #2.
Switch #1 and #2 are accessible
through a slot located in the bottom of
the chassis.
Fig. 4 - Selected desired alarm options
Work Surface Monitoring
The Model 724 monitors its
connection to ground and the
grounding of a 3M ESD work surface.
A loop resistance is measured from
the monitor, through a 3M
™
2380
Monitor/Table Mat Cord to the work
surface (Section 2), across the
conductive layer of the work surface,
through the grounding wire of the
work surface to an electrical ground
and finally back to the monitor through
the 724 grounding wire. If the
resistance of the loop exceeds
3.7 Megohms* the work surface high
red lamp (M) will illuminate and all
green lamps will be extinguished. If
DIP switch #2 is in the ON position
(Fig. 4) the audible alarm will activate.
If no ESD work surface is to be
monitored, the 3M 2380 Monitor/Table
Mat Cord and the ground wire of the
724 must be connected to an electrical
ground (Section 3). This is done to
ensure that the 724 is providing a
ground connection for the operators.
Again, if the loop resistance exceeds
3.7 Megohms the work surface high
red lamp (M) will illuminate and the
alarm will activate if selected.
Caution
The grounding wire from the work
surface and the ground wire from
the Model 724 monitor must be
attached to separate electrical grounds.
The work surface monitoring function
is active any time that the power supply
for the monitor is plugged in.
Caution
Disconnect the 3M 2380 Monitor/
Table Mat Cord to prevent possible
damage to the Model 724 monitor
before testing the resistance of the
work surface with a high voltage
megohmmeter.
* Resistance values are ±15%
DIP Switch
Switch #1
Loud
Switch #2
On
Model 724 Bottom View
Soft
Model 724 bottom view
DIP switch
Off
On
Loud
Switch #2
Switch #1