3M 725 User manual

3M™ 725 Workstation Monitor Properties
Typical Properties
Dimensions 2.5 in. x 2.6 in. x 1.1 in.
(6.4 cm x 6.6 cm x 2.8 cm)
Power Supply 9 Volt alkaline battery (not supplied)
Test Voltage 9 Vdc maximum
Test Current Less than 1 microamp
Upper Resistance Limits Wrist Strap: 35 Megohms
Ground Clip: 10 Megohms
Accuracy +15%
Environmental Operating Conditions Temperature:
Humidity:
Max. 110o F (43o C)
Min. 50o F (10o C)
Max. 75% R.H.
Accessories 723 Belt Clip

3
Model 725 Wrist Strap Monitor
Instructions

2
Index
SectionPage
Safety Information...................................................................................................3
1.Theory of Operation..........................................................................................4
2.OperatingYour System.....................................................................................6
3.Installation When Attaching to a Static Control Work Surface........................7
4.Installation Under Work Bench.........................................................................8
5.Installation Using 723 Belt Clip.......................................................................9
6.Parking Clip......................................................................................................9
7.Battery Replacement.........................................................................................9
8.Verification Procedure for the Model 725 Monitor.........................................10
9.Specifications..................................................................................................11
10.Parts Included..................................................................................................11
11.Required Accessories and Optional Available Parts.......................................12
12.Additional Wrist Strap Monitoring Information.............................................13
13.Warranty..........................................................................................................14

3
CAUTION
• Incorrect grounding of an operator may cause electrostatic discharge
(ESD) damage to components or assemblies being handled. For proper
grounding of the operator when using the 3M 725 Wrist Strap Monitor,
connecting to an electrical ground with the supplied ground wire and metal
ground clip is required.
• Verify that the electrical ground point is suitable. If you are not sure what a
suitable ground is, contact a licensed electrician before installation.
Explanation of Symbols
– Caution: refer to user instruction manual.
– See user instruction manual for explanation of the indicator lamp.
– See user instruction manual for explanation of the audible alarm.
Safety Information
Intended Use
The 3M™ Model 725 Wrist Strap
Monitor is designed to monitor the
operation of a wrist strap grounding
system for a single operator. This
product has been designed and tested
for use with 3M™ Dual Conductor
Wrist Straps and 3M™ Work Surfaces
Grounding Systems (Fig. 1). This unit
is powered by a 9 volt battery. Use of
other components may cause improper
performance and or an unsafe
condition.
Read and Understand all Safety Information Before
Operating this Equipment.

4
Section 1.
Theory of Operation
(Refer to Fig. 1)
The 3M™ Model 725 Wrist Strap
Monitor is designed to monitor the
operation of the wrist strap grounding
system of a single operator. The
system features special wrist bands
and ground cords that contain two
independent conductors.*
The Model 725 Monitor performs a
resistance measurement by applying an
electrical current of less than 1 µA.
The path for the current is through one
conductor of the wrist strap ground
cord that contains a current-limiting
resistor, through one side of the wrist
band, through the skin of the wearer
under the band, through the second
side of the wrist band, through the
second conductor of the wrist strap
ground cord that contains a current-
limiting resistor, and finally back to
the monitor.
If the resistance of the wrist strap loop
is less than 35 megohms**, the wrist
strap ground cord, wrist band, and the
interface of the wrist band to the arm
of the wearer are considered to be
functioning correctly. If the measured
resistance is over 35 megohms**, a
red lamp flashes along with a chirping
audible alarm.
In addition, the Model 725 monitors
the ground clip connection to a
predetermined electrical ground.
This is accomplished by measuring
the resistance from the monitor,
through one conductor of the
monitor’s ground cord and metal clip,
through the ground point conducting
medium, through the other metal clip
and conductor of the monitor’s ground
cord, and finally back to the Model
725 Monitor. If the resistance of this
loop exceeds 10 megohms***, a red
lamp will illuminate with a continuous
audible alarm. This indicates that
there is a problem with the monitor’s
ground cord or the ground point
connection.
Fig. 1 - Model 725 Wrist Strap Monitor with dual conductor wrist strap assemblies
Model 725
Wrist Strap
Monitor
Dual Conductor
Metal Wrist Strap* Dual Conductor
Fabric Wrist Strap*
* 3M Dual Conductor Cord & Wrist Band are
required for use with the 725 Monitor,
ordered separately. ** Resistance values are ±15%
*** Resistance values are +15%, -50%

5
Caution
The Model 725 Monitor does not have
the capability of verifying that the
ground point is a suitable ground. If
you are not sure what a suitable ground
is, contact a licensed electrician before
installation.
The Model 725 Monitor requires only
a small amount of current to operate.
When the red lamp and the audible
alarm are activated simultaneously the
monitor requires approximately 5 µA
of current. When the lamp and alarm
are not activated (normal condition)
the monitor requires approximately
50 µA of current.
As with any battery operated electronic
device, the life of the battery will be
determined by the frequency of use.
However, for the Model 725 Monitor
you can expect a battery life of
approximately one year in continuous
operation under normal conditions.
Note:
Use an alkaline battery for longer life.
The Model 725 monitors the battery
voltage and alerts the operator when it
is necessary to change the battery.
When the battery voltage falls below
6 volts the red lamp will illuminate
with no audible alarm. At this time the
Model 725 is still operational, making
reliable resistance measurements
of the wrist strap assembly and the
ground connection.
Voltage on Operator when Connected
to the Model 725 Monitor
There is a concern about the voltage
that is applied to an operator while
they are connected to a monitor.
Some of today’s electronic
components are extremely sensitive
to electrostatic discharge from a person
(less than 10 volts). The following
chart for the Model 725 Monitor
illustrates the level of voltage that will
appear on the operator under various
resistance conditions.
Voltage on Operator When Connected to the Model 725 Monitor
Condition Observed Voltage
No Skin Resistance 0.8V
200K Ohm Skin Resistance 0.9V
Likely Case Before Alarm 3.5V
Worst Case Before Alarm 6.8V
Absolute Worst Case 9.0V

6
Note:
For more information about wrist strap
monitoring see Additional Wrist Strap
Monitoring Information (Section 12).
Section 2.
Operating Your System
Fig. 2
To operate the 3M™ Model 725 Wrist
Strap Monitoring system, attach the
monitor’s (6 ft.) ground cord with
dual conductor ground clip to a
suitable ground.
Caution
If you decide not to use the dual
conductor ground clip that is attached
to the monitor’s ground cord in the
way described in this user instruction
manual, observe the following
precaution: Attach each of the two
wires of the monitor’s ground cord
to separate ground bonding points.
By attaching the wires to the same
ground but at different physical
locations, the monitor can check for
loose or lost connections.
Attach a 3M™ Dual Conductor
Ground Cord to a 3M™ Dual
Conductor Wrist Band. Place the wrist
band on your wrist and plug the cord
into the jack on the front of the Model
725 Monitor. Plugging into the jack
activates the monitor and causes it to
emit a short beep and the red lamp to
momentarily flash. If the red lamp
flashes with an intermittent audible
alarm or at any time during use, the
resistance of the wrist strap assembly
is greater than 35 megohms.** If the
red lamp and the audible alarm remain
on continuously, check the dual
conductor ground clip connection.
The system is now ready for use.
Note:
Operators may complain that the
alarm is sounding too often until they
learn to adjust the wrist band to fit
securely or apply an approved skin
moisturizer on a frequent basis.
Please remember that the monitor is
informing you that the operator is
exceeding the established static
control requirement for resistance
to ground when wearing a static
protective wrist strap assembly.
These alarms alert the operator when
sensitive electronics are possibly being
exposed to static electricity. Prior to
incorporating the wrist strap monitor
into your static control process, the
operator was unaware of these events.
**Resistance values are ±15%

7
Section 3.
Installation When Attaching
to a Static Control Work
Surface
Fig. 3
The Model 725 Monitor can be used to
ground a work surface while providing
a monitored grounding point for an
operator. To ground a work surface, the
Model 725 Monitor contains a snap
located on its bottom cover, that is
connected internally to the monitor’s
ground cord. To use this feature there
must be a female (10 mm) snap
fastener attached to the grounding
layer of the work surface. Simply align
the male snap on the monitor with the
female snap on the work surface and
press downward on the monitor. The
work surface is now automatically
grounded through a one megohm
resistor by the Model 725 Monitor.
Note:
Although the work surface is
grounded by the Model 725 Monitor,
it is not monitoring the ground to the
work surface.
3M™ 8200 Series Work Surfaces use
the female 10 mm (3M™ Model 3050)
snap fastener for grounding. 3M™
1800, 8300, and 8800 Series Work
Surfaces use the female 10mm
(3M™ Model 3034) snap fastener for
grounding. In addition all 3M™ 8500
Series Portable Field Service Kits
include the 10 mm (3M Model 3034)
snap fastener.
Use of an optional 3M™ 3057 Stand-
By Jack at the work station extends the
life of the monitor’s input jack. The
user disconnects the wrist strap
ground cord from the wrist band
and plugs into the 3057 jack which is
mounted at the work station.
Plugging into the 3057 jack prevents
the Model 725 from continuously
alarming when disconnected
from the wrist band.
The system is now ready for use.

8
Section 4.
Installation Under Work
Bench
Fig. 4
The Model 725 can be mounted under
a work bench by securing with two #8
screws (not supplied) through the
mounting hole tabs located on the top
cover.
Note:
Use of the monitor in this way
precludes grounding a work surface
through the snap connector on the
bottom of the monitor. A static control
work surface, if present, would require
grounding separately through an
additional ground cord.
When mounting the Model 725
Monitor under a work bench for non
mobile use, remove the parking clip
(Section 6) from the Model 725
Monitor using a small screwdriver. The
Model 725 Monitor is now ready to
mount.
Position the monitor so that it is
convenient for the operator to plug
their wrist strap ground cord into the
jack on the front of the monitor. It is
recommended that the front face of the
monitor be flush or slightly recessed
from the front edge of the work bench.
Attach the monitor to the work bench
with the screws. It may be necessary
to pre-drill pilot holes for the screws.
Attach the dual conductor ground clip
or each wire of the monitor’s dual
conductor ground cord to a suitable
ground.
Caution
If you decide not to use the dual
conductor ground clip that is
attached to the monitor’s ground
cord in the way described in this
user instruction manual, observe the
following precaution:Attach each of
the two wires of the monitor’s ground
cord to separate ground bonding
points. By attaching the wires to the
same ground but at different physical
locations, the monitor can check for
loose or lost connections.
Use of an optional 3M 3057 Stand-By
Jack at the work station extends the
life of the monitor’s input jack. The
user disconnects the wrist strap
ground cord from the wrist band
and plugs into the 3057 jack which is
mounted at the work station.
Plugging into the 3057 jack prevents
the Model 725 from continuously
alarming when disconnected from the
wrist band.
The system is now ready for use.

9
Section 5.
Installation Using 723 Belt
Clip (Optional)
An optional belt clip is available to
further enhance the portability feature
of the Model 725 Monitor. This
expands the use of the monitor when
operators need to be highly mobile as
in an electronic manufacturing
environment. Simply attach the belt
clip with female snap connector to the
male snap connector on the monitor
bottom cover. Slide the clip over your
belt in a convenient place, so that the
wrist strap ground cord will not
interfere with normal body
movements when attached to the
monitor.Attach the dual conductor
ground clip to a suitable ground
at the work location. During
mobility, attach the dual conductor
ground clip to the parking clip on
the Model 725 Monitor
(See Section 6).
Section 6.
Parking Clip
Fig.5
A parking clip is supplied with the
Model 725 Monitor allowing mobile
users to silence the ground clip
disconnect alarm. Attaching the dual
conductor ground clip to the parking
clip prevents unnecessary
disconnecting/connecting of the wrist
strap ground cord from the input jack
during mobility. An added benefit of
this feature is that it extends the life of
the dual conductor ground cord plug
and the monitor’s input jack. The
parking clip is already attached to the
mounting tab of the Model 725
Monitor. If the Model 725 is to be
mounted under a work bench for
permanent use, remove the parking
clip from the Model 725 Monitor using
a small screwdriver.
Section 7.
Battery Replacement
Fig. 6
When only the red lamp illuminates on
the Model 725 Monitor, it is time to
change the battery. Unplug the wrist
strap ground cord from the 725
Monitor jack before proceeding.

10
Remove the top cover of the Model
725 case by squeezing the two tabs
(grooved area located on the bottom
cover) inward while lifting the top
cover. Remove the used battery
carefully by using a pulling-twisting
motion to unsnap the battery from the
connectors on the printed circuit board.
Install a new 9 volt alkaline battery by
supporting the snap connectors on the
printed circuit board with your fingers,
while using a pushing-twisting motion
to fully seat the terminals of the battery
into the snap connectors.
Note:
Use an alkaline battery for longer life.
Pass the monitor’s ground cord
through one of the two exit wire slots
in the bottom half of the case. Align
the rear locking tab on the top cover, to
the tab slot on the bottom cover while
maintaining the ground cord in the
desired wire slot. Rotate the top cover
downward onto the two side locking
tabs of the bottom cover and snap
firmly into place.
Section 8.
Verification Procedure for
the Model 725 Monitor
The Model 725 Wrist Strap Monitor
cannot be recalibrated after the initial
factory calibration. However, the
following steps can be used to
determine if the Model 725 is
operating within its specifications.
Equipment Needed:
• Resistance Substitution Box (RSB),
1 Ohm to 45 Megohms ± 1%.
• One two conductor cable with
standard 3.5 mm (miniature) phone
plug attached on one end and
appropriate connectors on the other
end to connect to a RSB.
• Two single conductor wires with
clip style on one end and
appropriate connectors on the other
end to connect to a RSB.
Note:
Two conductor cables must have an
isolation resistance of >1 Gigohm
between conductors. Two separated
wires may also be used to obtain
higher isolation resistance.
Procedure:
a) Install a new 9 volt battery into the
Model 725.
b) Short the dual conductor ground
clip by attaching to a conductive
metal object such as a coin.
c) Plug the phone jack test cord into
the wrist strap jack on the front of
the monitor and attach the other end
of the cord to the RSB.

11
Set the RSB as follows and observe the
lamp and audible alarm:
Wrist Strap
29.8 Megohms - Red lamp OFF,
audible alarm OFF.
40.2 Megohms - Red lamp ON
(Flashing), audible alarm ON
(Chirping).
Ground Clip Disconnect
d) Connect the two single conductor
wires to the RSB. Attach the other
ends of the wires with clips to the
metal jaws of the Model 725
Monitor dual conductor ground clip.
Be sure to prevent the clips from
contacting each other. Plug in the
phone jack test cord into the wrist
strap jack on the front of the
monitor and short the opposite ends
together.
Set the RSB as follows and observe the
lamp and audible alarm:
5.0 Megohms - Red lamp OFF,
audible alarm OFF
11.5 Megohms - Red lamp ON
(Continuous), audible alarm ON
(Continuous tone).
Section 9.
Specifications
Model 725 Monitor Size:
2.5 x 2.6 x 1.1 in. (6,4 x 6,6 x 2,8 cm)
Accuracy: ± 15%
Test Voltage: 9 Vdc Open circuit
Test Current: Less than 1 microamp
Power Supply Requirements:
9 Volt alkaline battery
recommended (Not supplied)
Environmental Operating Conditions:
Temperature: Maximum 110°F, (43°C)
Minimum 50°F, (10°C)
Humidity: Maximum 75% R.H.
Section 10.
Parts Included
• 1 ea. Model 725 Wrist Strap Monitor
with 6 ft. dual conductor ground
cord/clip and parking clip.
• 1 ea. User Instruction Manual &
Verification Procedure

12
Section 11.
Required Accessories and Optional Available Parts
Model No. Description Size
2361 Dual Conductor Fabric Wrist Strap* small
2362 Dual Conductor Fabric Wrist Strap* medium
2363 Dual Conductor Fabric Wrist Strap* large
2364 Dual Conductor Fabric Wrist Band small
2365 Dual Conductor Fabric Wrist Band medium
2366 Dual Conductor Fabric Wrist Band large
2368 Dual Conductor Fabric Wrist Band adjustable
2381 Dual Conductor Metal Wrist Strap* small
2382 Dual Conductor Metal Wrist Strap* medium
2383 Dual Conductor Metal Wrist Strap* large
2384 Dual Conductor Metal Wrist Band small
2385 Dual Conductor Metal Wrist Band medium
2386 Dual Conductor Metal Wrist Band large
2360 Dual Conductor Coil Cord 5 ft. (1,5 m)
2370 Dual Conductor Coil Cord 10 ft. (3,0 m)
2371 Dual Conductor Coil Cord 20 ft. (6,1 m)
3057 Stand-By Jack 1.9 x 1.3 x 1.1 in. (4,8 x 3,3 x 2,8 cm)
723 Belt Clip
* Includes Band & Cord

13
Section 12.
Additional Wrist Strap
Monitoring Information
Suggested reading on wrist strap
requirements and wrist strap
monitoring:
• EIA 625 - Requirements for
Handling Electrostatic-Discharge-
Sensitive (ESDS) Devices.
• EN100015/1 - Protection of
Electrostatic Sensitive Devices.
• 3M Tech. Response #123 - Pulsed
Current vs. Constant Current in
Work Station Monitors.
• 3M Static Digest Issue No.1, 1998 -
Disc Drive Industry - Static Control
Considerations.
Note:
The 3M references are available by
calling 3M Electronic Handling &
Protection Division Customer Service
Department at 1-800-328-1368.
Industry standards (EIA & EN), are
available through Global Engineering
Documents at 1-800-854-7179.

14
Section 13.
Warranty
Limited Warranty - 3M expressly
warrants that for a period of one year
from the date of purchase, 3M static
control products will be free of
defects in materials (parts) and
workmanship (labor).
Defects occuring during the warranty
period will be repaired or products
will be replaced at 3M’s option and
expense, if 3M receives notice during
the warranty period. Defective
products must be returned to 3M with
proof of purchase date.
Warranty Exclusions - THE
FOREGOING EXPRESS
WARRANTY IS MADE IN LIEU OF
ALL OTHER PRODUCT
WARRANTIES, EXPRESS AND
IMPLIED.
INCLUDING FITNESS AND
MERCHANT ABILITY. The express
warranty will not apply to defects of
damage due to accidents, negligence,
misuse, alterations, operator error,
or failure to properly maintain, clean,
or repair products.
Limit of Liability - In no event will
3M or Seller be responsible or liable
for special, incidental, or
consequential losses or damages,
whether based in tort or contract.
Fulfillment of 3M’s warranty
obligations will be Customer’s
exclusive remedy and 3M’s and
Seller’s limit of liablity for any breach
of warranty or otherwise.