Wrist Strap Tester 746
Instructions
European Version
March 2005
78-8136-2118-8
1.0 General
3.0 Description
Wrist straps are the primary method to minimize charge
generation on the human body. They must be able to
drain this charge as rapidly as it is generated.
The 3M™ Wrist Strap Tester 746 operates as a battery
powered tester, or additionally with an AC power supply
as backup for the battery. It is designed to be used either
as a stationary or portable piece of equipment. The 746
is supplied with a 9V alkaline battery - a power supply is
optional.
For this reason, it is important to test wrist straps on a
regular basis to ensure they are functioning properly, and
the test results should be recorded.
The tester has a permanent, internally set resistance range
which extends from 750 kΩ to 10 MΩ. When tested, if the
wrist strap is within this resistance range, the green LED
will illuminate. The red LED indicates that the resistance
to ground of the tested device or system is out of range.
2.0 Declaration of Conformity
The 3M™ Wrist Strap Tester 746 is in conformity with
the regulations of the EMC-directive 89/336/EWG.
The following standards have been taken into account
while designing and manufacturing the instrument:
Accessories
- Instruction Manual
- Wall mounting kit, 3M™ Dual Lock™ system and
template
- Battery
EN 60204-1/85
EN 60204-1/91
EN 61010 (Safety)
EN 50082-1/92
EN 50082-2/92
- Cover for wrist strap plug-in jack
5
746
wrist strap tester
o.k.
o.k.
4
2
6
3
9
7
1
8
1 500 mm
(5 feet)
figure 1
78-8136-2118-8
3
For checking the resistance range of the ground
cord, leave the plug end of the ground cord
attached to the tester and unsnap the cord from
the wrist band. Place the metal side of the ground
cord snap against the metal plate of the tester
and depress until one of the LEDs is illuminated.
If the red LED is illuminated, the ground cord
is outside the resistance range and should be
replaced. If the green LED illuminates, the
ground cord can be used, but the wrist band may
have to be replaced.
4.0 Specifications
Base unit:
158 x 95 x 33 mm (6.25 x 3.75 x 1.25 inches)
Weight:
200 g (7 ounces) without battery
Battery:
9V alkaline type, e.g. IEC 6F22
Tolerance:
750 kΩ + 20%/-0%, 10 MΩ ± 10%
Note: In some cases, high contact resistance between
the person's skin and wrist band will cause the tester
to show a fail/red LED condition. This resistance may
be caused by dry skin or hair in the wrist area. If these
possibilities do not match to the operator, the wrist
band should be replaced.
Measurement Voltage:
DC (19±1) V (open circuit)
Power Supply (not included):
DC 9V, regulated, 75mA (50Hz)
5.0 How to Use
5.6
If the "battery" LED illuminates at any time,
replace the battery.
5.1
Insert 9V battery and make sure the ON/OFF
switch at the upper left side on the unit is in
the ON position. The OFF position avoids
discharge of the battery if the metal contact plate
is accidentally depressed while the unit is not
in use. The unit is then ready for operation. The
backup of the battery can be achieved by using
an AC Power Supply. In that case, connect the
AC power supply to the jack at the base of the
unit. Plug the power supply into an AC 230V
outlet.
Wall Mounting
5.7
The enclosed 3M™ Dual Lock™ adhesion discs
shall be screwed on the wall using the attached
template approximately 1500 mm (5 feet)
parallel off the floor. Drill three holes of 5 mm
(0.2 in) diameter at marked location.
5.8
The enclosed 3M Dual Lock adhesion strips must
be adhered to the rear of the 3M™ Wrist Strap
Tester 746 parallel to the bottom edge and below
the battery compartment.
5.2
Fit the plastic cover onto the wrist strap plug-in
jack that is not being used. If the "battery" LED
illuminates, replace it immediately.
Note: Make sure the area on the unit in which
the Dual Lock adhesion strips are placed is
free of dust and dirt. Press the tester firmly
against the discs for fixing on the wall.
Wrist Strap Test
5.3
Put the wrist band on with ground cord attached,
and insert the ground cord plug into the wrist
strap plug-in jack.
5.9
For removal, lift the tester 746 at the two top
corners with both hands.
5.4
5.5
Depress the metal contact plate and hold it.
One of the indicator LEDs will illuminate.
An illuminated green LED indicates that the
wrist strap performs within the resistance range
of 750 kΩ to 10 MΩ. If a "red" condition is
indicated, it is advisable to check the ground cord
individually for its resistance.
4
78-8136-2118-8
Wrist strap test circuit check:
Connect the resistance substitution box to the 746 as
shown in figure 2.
6.0 Calibration Procedures
The 3M™ Wrist Strap Tester 746 cannot be adjusted,
but the following steps can be used to determine that the
tester is operating within its specification.
Set the resistance substitution box to each value of
resistance indicated in the test table and press contact
plate A.
Equipment needed:
1. Resistance Substitution Box
The LEDs will indicate as shown below if the unit is
functioning within specifications.
(750 kΩ - 11 MΩ, tolerance < 2%)
2. 2 leads (to connect the resistance box)
Resistance
substitution box
settings
Resistance
range of
the 746
LED
indication
*750 kΩ
900 kΩ
red
green
750 kΩ
10 MΩ
9.0 MΩ
11.0 MΩ
green
red
*This example is used in figure 2.
746
wrist strap tester
700 k
900 k
9.0 M
11.0 M
o.k.
o.k.
A
Resistance substitution box
Crocodile clip
figure 2
78-8136-2118-8
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3M™ Wrist Strap Tester 746 Logbook
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Example :
Not ok :
ok :
Unit calibrated on:
By:
x
Next calibration on:
Serial number:
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78-8136-2118-8
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This product will be free from defects in material and manufacture for a period of one (1) year from the time of purchase. 3M MAKES NO
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Electronic Solutions Division
6801 River Place Blvd.
Austin, TX 78726-9000
Litho in USA
© 3M 2005 78-8136-2118-8
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