3M Static Monitor 790 User manual

User’s Guide
3M™Static Monitor 790

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Table of Contents
Section Page
Intended Use .........................................................................................................3
1.0 Theory of Operation ....................................................................................4
2.0 Attaching Ground & Chassis Cords ............................................................5
3.0 Attaching the 3M™Static Monitor 790 to a Workbench or Equipment
Chassis.........................................................................................................8
4.0 Operating Your System................................................................................9
5.0 Connecting an Operator to the Static Monitor 790 ...................................11
6.0 Verification Procedure ...............................................................................12
7.0 Specifications ...........................................................................................14
8.0 Parts Included............................................................................................15
9.0 Required Accessories and Optional Available Parts..................................15
Regulatory Information and Warranty ......................................................16
Read and understand all safety information before operating this equipment.

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INTENDED USE
The 3M™Static Monitor 790 is designed to monitor the operation of two wrist
strap grounding systems and the ground connection of a specified equipment
chassis. This product has been designed and tested for indoor use only and with
3M™Dual Conductor Wrist Bands 2300VM Series and 3M™Dual Conductor
Ground Cord 2300 Series.* The monitor operates from a 120VAC adaptor
that is included in the North America version. Outside North America, obtain
an appropriate AC adapter meeting the specifications as stated in Section 7
Specifications under Power Supply Requirements. The product has not been
tested or proven safe for other uses.
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 Static Monitor
790, use the three-prong AC adapter or the supplied chassis/ground cords specified in the user
instruction manual.
• The Static Monitor 790 does not have the capability of verifying that the ground point is a suitable
ground. Verify that the electrical ground point is suitable prior to use. If you are not sure what a
suitable ground is, contact a licensed electrician before installation.
• When using two chassis/ground cords, attach each of the cords to separate ground bonding points.
By attaching the cords to the same ground but at different physical locations, the monitor can
check for loose or lost connections.
• At the end of product life, dispose of product in accordance with governmental regulations.
Explanation of Symbols
CAUTION: refer to user instruction guide
Chassis ground
Electrical ground
Power input connector polarity (center negative)
See user instruction manual for explanation of the indicator lamps
*3M Dual Conductor Cords & Wrist Bands 2300VM Series are required for use with the Static
Monitor 790, ordered separately.

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1.0 Theory of Operation
The 3M™Static Monitor 790 is designed to continuously monitor the voltage
level on an operator(s) using a high impedance voltage measurement circuit.
The measured operator’s voltage is compared to one of four user selectable
(1V, 3V, 6V and 9V) internal reference voltages. An alarm will sound with a
corresponding red flashing lamp(s), when an operator’s voltage level (caused by
static generation) exceeds the selected internal reference voltage.* In addition,
a wrist band contact detection circuit is also employed to let the user know if
the wrist band is being worn improperly or has experienced a loss of continuity
between the ground cord and wrist band.
The ground connection of the Static Monitor 790 is continuously monitored
through a low DC current-loop measurement circuit. The ground connection of
an equipment chassis can also be monitored when connected in series with the
monitor’s ground measurement circuit. An alarm will sound with corresponding
red lamps, when this loop resistance exceeds 10Ω.**
If all monitored components are operating within the selected operating
parameters of the Static Monitor 790, a green lamp will illuminate.
The Static Monitor 790 uses a modified version of the 3M™Dual Conductor
Wrist Band (VM Series) and the standard 3M™Dual Conductor Grounding Cord
(see Accessories Section).
*Voltage alarm levels ±15%
**Ground disconnect ±20%
***Ordered separately
AC Adapter Mounting Plate
3M™Static Monitor 790
Chassis/Ground
Cords with Two-
Wire Connector
Figure 1 - 3M™Static Monitor 790

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2.0 Attaching Ground and Chassis Cords
Tools required – Small blade screwdriver.
Refer to Figures 2A, 2B, 3A and 3B for this section.
Figure 2A and 2B-Attachment of Ground Cords
Note: Perform Step #1 below when monitoring directly to the ground connection (Fig. 3A).
Perform Step #2 when monitoring the ground connection through a grounded chassis (Fig. 3B).
2.1 Installation of Static Monitor 790 with Chassis Terminal Connected Directly
to Earth/Electrical Ground
Determine how you want to ground the Static Monitor 790:
a. If you are grounding the Static Monitor 790 through the 3-Wire AC adaptor
(North America) supplied, perform the following steps:
• Attach the tinned ground wire of the AC adaptor to the ground terminal of
the two-wire connector by inserting it into the opening and securing with
screwdriver.
• Attach one of the supplied Static Monitor 790 Chassis/Ground Cords
(tinned end) to the chassis terminal of the twowire connector in the same
manner.
• Attach the ring terminal end of the Chassis/Ground Cord to an earth/
electrical ground with a screw (not supplied).
• Plug the two-wire connector into the jack at the rear of the Static Monitor
790.
The 3M™Static Monitor 790 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.
CAUTION
Two-Wire Connector
AC Adapter Ground Wire
AC Adapter
DC Plug
790 Chassis/Ground Cord
Attach 3M™Static Monitor 790
Chassis/Ground Cord or AC Adapter
Ground Wire

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b. If you are grounding the 3M™Static Monitor 790 through a Chassis/
Ground Cord perform the following steps:
• Attach one of the supplied Chassis/Ground Cords (tinned end) to the
ground terminal of the two-wire connector by inserting it into the
opening and securing with screwdriver.
• Attach the other Chassis/Ground Cord to the chassis terminal of the two-
wire connector in the same manner.
• Attach the ring terminal ends of both cords separately with two screws
(not supplied) to an earth/electrical ground.
• Plug the two-wire connector into the jack at the rear of the Static
Monitor 790.
Figure 3A and 3B - 3M™ Static Monitor 790 Connected Directly to Ground or Through Equipment Chassis Ground
When using two Chassis/Ground Cords, attach each of the cords to separate ground bonding
points. By attaching the cords to the same ground but at different physical locations, the monitor
can check for loose or lost connections.
CAUTION
3M™Static Monitor 790 Connected
Directly to Ground
3M™Static Monitor 790 Connected through
Equipment Chassis Ground
Rear of 790 Monitor
AC Adapter
Ground Wire
or Chassis/Ground
Cord
AC Adapter
Ground Wire
or Chassis/Ground
Cord
Chassis/Ground
Cord Chassis/GroundCord
Electrical Ground
Existing Equipment
Ground Wire

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2.2 Installation of 3M™Static Monitor 790 with Chassis Terminal Connected to
a Grounded Equipment Chassis
Determine how you want to ground the Static Monitor 790:
a. If you are grounding the Static Monitor 790 through the 3-wire AC
adaptor supplied, perform the following steps:
• Attach the tinned ground wire of the AC adaptor to the ground terminal
of the two-wire connector by inserting it into the opening and securing
with screwdriver.
• Attach one of the supplied Chassis/Ground Cords (tinned end) to the
chassis terminal of the two-wire connector in the same manner.
• Attach the ring terminal end of the Chassis/Ground Cord to the
equipment chassis with a screw (not supplied).
• Plug the two-wire connector into the jack at the rear of the Static
Monitor 790.
b. If you are grounding the Static Monitor 790 through a Chassis/Ground
Cord perform the following steps:
• Attach one of the supplied Chassis/Ground Cords (tinned end) to the
ground terminal of the two-wire connector by inserting it into the
opening and securing with screwdriver.
• Attach the other Chassis/Ground Cord to the chassis terminal of the two-
wire connector in the same manner.
• Attach the ring terminal end of the Chassis/Ground Cord connected
to the ground terminal of the two-wire connector, with a screw (not
supplied) to an earth/electrical ground.
• Attach the ring terminal end of the Chassis/Ground Cord connected to
the chassis ground terminal of the two-wire connector, with a screw (not
supplied) to an equipment chassis.
• Plug the two-wire connector into the jack at the rear of the Static
Monitor 790.
When using two Chassis/Ground Cords, attach each of the cords to separate ground
bonding points. By attaching the cords to the same ground but at different physical locations,
the monitor can check for loose or lost connections.
CAUTION

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3.0 Attaching the 3M™Static Monitor 790 to a Workbench or
Equipment Chassis
Refer to Figures 4, 5, and 6
Locate the Mounting Plate.
• Attach the Mounting Plate in the desired location using one of the following
methods:
a. Foam tape (already applied to the Mounting Plate). Clean the surface to be
mounted to with isopropyl alcohol. Remove release liner from tape before
mounting.
b. Two #8 pan head machine or wood screws (not supplied).
• Attach the Static Monitor 790 to the mounted plate as shown in Figure 4.
Align the plate with the opening on the bottom of the monitor and slide
forward onto plate until it latches.
Figure 4: Attachment of Mounting
Plate to 3M™Static Monitor 790
Figure 6: 3M™ Static Monitor 790
attached to equipment chassis
Figure 5: 3M™ Static Monitor 790
attached to workbench

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4.0 Operating Your System
Refer to Figures 7 and 8
Power Up
Apply power to the 3M™Static Monitor 790 by inserting the round connector
on the end of the AC adaptor, into the jack at the rear of the Static Monitor 790.
Plug the AC adaptor into an appropriate electrical outlet. The green lamp should
illuminate, signaling that the unit is operational and that there are no alarm
conditions. If the green lamp does not illuminate, but red lamps are illuminated
with audible alarm sounding, check all cords and ground connections.
Audible Alarm Volume Level
Select the desired audible alarm volume level at the rear of the Static Monitor
790 by sliding the switch to the Hi or Lo position.
Selection of the Reference Voltage
The Static Monitor 790 allows for the selection of one of four internal reference
voltages (1V, 3V, 6V and 9V) with 1V being the most sensitive setting and 9V
the least sensitive. Select a voltage level by sliding the switch to the appropriate
position. These ranges have been designed to accommodate global ESD
requirements. The selection of this operational parameter is based upon the user
s ESD control program requirements.
Fault Conditions – Lamps & Audible Alarms
For wrist strap malfunctions, the Static Monitor 790 indicates different alarms
for each operator; a slow audible beep/flashing lamp for the operator on the left
input side and a fast audible chirping beep/flashing lamp for the operator on the
right input side. For grounding/chassis-monitoring malfunctions, a continuous
tone is emitted with both lamps illuminated.
Fault Lamps
OK Lamp
Input Jack
Voltage
Selection
Switch
Input Jack
DC Power
Input Jack
Electrical
Ground
Chassis
Ground
Hi-Lo Volume
Level Switch
Figure 7: Front of 3M™Static Monitor 790 Figure 8: Rear of 3M™Static Monitor 790

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a. Red lamp(s) flashing with an audible alarm.
This alarm mode can be caused by two conditions and both are interrelated. If
either the voltage level on the operator is greater than the pre-selected internal
reference voltage or poor contact between the wrist band and the arm exist, the
alarm will activate.
If the 3M™Static Monitor 790’s alarm activates when the operator is not
moving (normally a non-charging situation), the cause is most likely due to
poor contact between the wrist band and the arm. The alarming period would
normally be long in duration (unless intermittent contact) during this type of
condition. Check contact between the wrist band and arm. Some operators
may have difficulty in providing sufficient contact to the wrist band because
of dry skin or arm hair. They may need to use an approved skin moisturizer or
reposition the wristband on the arm.
If the monitor’s alarm does not activate while the operator is not moving, then
the cause of the alarm was most likely due to a voltage being developed on the
operator. A high resistance between the operator and ground would allow the
operator to charge up as they moved about. The alarm period for this type of
fault would normally be short and coincide with their body movement.
Alarming can also be caused by an intermittent or high resistance in the wrist
strap’s dual conductor ground cord. Replace a suspect cord with a known good
ground cord or check the end to end resistance of the cord using an ohmmeter.
Approximately 1 megohm of resistance should exist between the tip to tip and
barrel to barrel contacts of the two plugs located on opposite ends of the cord.
Note: The operators may complain that the alarm is sounding too often until they learn to adjust the
wristband 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 voltage 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 static monitor into your static control process, the operator was unaware
of these events.
b. Two red lamps illuminated (continuously) with an audible alarm.
This indicates that a high resistance condition (greater than 10Ω) exists
between the Chassis/Ground Cord and ground. This will include the
equipment chassis ground if being monitored. Check the ground cords for
continuity and ground attachment points.