Desco 19656 Manual

TB-3091.E Page 1 of 7 © 2022 DESCO INDUSTRIES INC
Employee Owned
2A Dunhams Lane, Letchworth Garden City, SG6 1BE, United Kingdom • 01462 672005 • Website: DescoEurope.com
Dual Operator Continuous Monitor
Installation, Operation and Maintenance
Description
The Desco Dual Operator Continuous Monitor is a
workstation continuous monitor. It continuously monitors
the path-to-ground integrity of two operators and one
ESD worksurface. Mounting tabs make it suitable to
install in workbench or equipment settings, and the
Visual Status Display can be placed to increase alarm
visibility.
The Dual Operator Continuous Monitor is designed
with Wave Distortion Technology to provide stable
continuous monitoring of the path-to-ground and
presence of 1 megohm resistance of an operator’s wrist
strap. Audio and visual alarms activate (in less than
500 milliseconds) when the operator unintentionally
disconnects from the monitor, or the wrist strap
connection points are intermittent. The Dual Operator
Continuous Monitor also monitors for a worksurface
path-to-ground of less than 10 megohms and the
integrity of the electrical ground used to by the monitor
All Dual Operator Continuous Monitors are calibrated to
NIST standards and include a certificate.
March 2022
Wave Distortion Technology is the Most Reliable
Technology for the Continuous Monitoring of
Single-Wire (Conductor) Wrist Straps
“Wave Distortion” or vector impedance works by
applying a continuous test voltage of 1.2 volts
peak-to-peak at 1 to 2 microamperes (0.000002
amperes) to the wrist strap that is connected to the
continuous or constant monitor. The test voltage creates
a square wave that the monitor circuit compares to
established patterns. By monitoring the “distortions”, or
shape of the square wave, Wave Distortion Technology
determines if the monitored circuit is complete - the
operator is in the circuit and the total equivalent DC
resistance is within specifications. Wave Distortion
Technology produces a very fast alarm time and
minimal false alarms.
ANSI/ESD S20.20 section 7.3 states “Compliance
verification records shall be established and maintained
to provide evidence of conformity to the technical
requirements.” Per ANSI/ESD S1.1 Annex A.3 Daily
(wrist strap system) testing may be omitted if constant
monitoring used.” Per ESD Handbook ESD TR 20.20
section 5.3.2.4.4 “Typical Test programs recommend
that wrist straps that are used daily should be tested
daily. However, if the products that are being produced
are of such value that knowledge of a continuous,
reliable ground is needed, and then continuous
monitoring should be considered or even required.”
The Dual Operator Continuous Monitor and its
accessories are available as the following item numbers:
Item Description
19656 Dual Operator Continuous Monitor,
with Universal Power Adapter
98221 Wave Distortion Monitor Verification Tester
19658 Power Adapter, 100-240 VAC Input, 9 VDC 3
A Output, IEC C14 Inlet
200220 Power Cord, Europe
200225 Power Cord, UK
Made in the
United States of America
TECHNICAL BULLETIN TB-3091.E
Figure 1. Desco Dual Operator Continuous Monitor

TB-3091.E Page 2 of 7 © 2022 DESCO INDUSTRIES INC
Employee Owned
2A Dunhams Lane, Letchworth Garden City, SG6 1BE, United Kingdom • 01462 672005 • Website: DescoEurope.com
Packaging
19656 Dual Operator Continuous Monitor
1 Dual Operator Continuous Monitor
1 Visual Status Display
1 Modular Cable, 7' Length
1 Mat Monitor Cord (White)
1 Countersunk Washer
1 Flat Head Screw, 6-32 x 1/4"
4 Pan-Head Screw, #6 x 3/8"
2 Dual Lock Fastener Set, 2" Length
2 10 mm Interchangeable Park Snap
2 10 mm Operator Jack Adapter
1 Power Adapter with IEC C14 Inlet, 9 VDC
1 Certificate of Calibration
Figure 2. Desco 19656 Dual Operator Continuous
Monitor packaging contents

TB-3091.E Page 3 of 7 © 2022 DESCO INDUSTRIES INC
Employee Owned
2A Dunhams Lane, Letchworth Garden City, SG6 1BE, United Kingdom • 01462 672005 • Website: DescoEurope.com
Features and Components
Dual Operator Continuous Monitor
Function Procedure
Audible Alarm
Volume
1. Push and release the switch to
toggle the buzzer's volume.
2. The volume will toggle from low,
medium, and high settings.
Enable / Disable
Mat Monitor
Circuit
1. Push and hold the switch until
all LEDs illmuniate on the
Visual Status Display.
2. Release the switch.
3. An illuminated MAT LED
indicates that the mat
monitor circuit is enabled. A
non-illuminated MAT LED
indicates that the mat monitor
circuit is disabled.
C. Park Snaps: Allows the operator to disconnect (and
park) a wrist strap when leaving the workstation, without
creating a false alarm. Touch the park snap or park
switch, and the monitor's audible alarm will disable for
approximately 8 seconds. Use this time to disconnect
the wrist cord from the wristband, and attach it to the
park snap or remove the banana plug from the jack.
Upon returning to the workstation and disconnecting
the wrist cord from the park snap, the operator has
approximately 8 seconds to reconnect the wrist cord to
a worn wristband before activating the alarm.
D. Monitored Operator 1 Jack: Insert the single-wire
wrist cord here to monitor the operator's connection to
ground.
E. Park Switch: Allows the operator to disconnect (and
park) a wrist strap when leaving the workstation, without
creating a false alarm. Touch the park snap or park
switch, and the monitor's audible alarm will disable for
approximately 8 seconds. Use this time to disconnect
the wrist cord from the wristband, and attach it to the
park snap or remove the banana plug from the jack.
Upon returning to the workstation and disconnecting
the wrist cord from the park snap, the operator has
approximately 8 seconds to reconnect the wrist cord
to a worn wristband before activating the alarm. The 8
second timer is indicated by the growing intensity of the
park switch's blue LED. The blue LED will pulse when
the operator jack is vacant to indicate standby mode.
F. Monitored Operator 2 Jack: Insert the single-wire
wrist cord here to monitor the operator's connection to
ground.
G. Mat Monitor Screw Post: Verifies that the
worksurface's path-to-ground is less than 10 megohms.
Connect the white mat monitor cord here.
H. Display Jack: Use the included modular cable to
connect the Visual Status Display to this connector. The
monitor will alarm should the modular cable disconnect
from this connector.
I. Power Jack: Connect the included 9 VDC power
adapter here.
Figure 3. Dual Operator Continuous Monitor features
and components
A B
G H I
C
D
F
C
E
A. Power Relay Stereo Jack: Not applicable in the UK
or Europe.
B. Set Switch: Toggles the monitor's settings for the
audible alarm and mat monitor circuit.

TB-3091.E Page 4 of 7 © 2022 DESCO INDUSTRIES INC
Employee Owned
2A Dunhams Lane, Letchworth Garden City, SG6 1BE, United Kingdom • 01462 672005 • Website: DescoEurope.com
Visual Status Display
A. Operator LEDs: Illuminates green when the
operator is properly grounded. Illuminates solid red and
audible alarm sounds when the operator is not properly
grounded.
B. Mat LEDs: Illuminates green when the worksurface
is properly grounded. Illuminates red and audible alarm
sounds when the worksurface is not properly grounded.
C. Display Jack: Use the included modular cable to
connect the Dual Operator Continuous Monitor to this
connector. The monitor will alarm should the modular
cable disconnect from this connector.
Installation
1. Remove the Dual Operator Continuous Monitor from
the carton, and inspect for damage.
2. Locate an appropriate AC outlet near the Dual
Operator Continuous Monitor, and test it for proper
wiring and grounding prior to use. The Desco
Europe AC Outlet Analyzer or similar test equipment
may be used to verify the outlet's functionality. Use
item 224715 for 220 VAC European outlets and item
224713 for 220 VAC UK outlets.
3. Determine the mounting location of the Dual
Operator Continuous Monitor. Its operator jacks
should be accessible to its operators. Use its
mounting tabs and included pan head screws or
dual lock fasteners to secure it underneath a table
top.
4. Determine the mounting location of the Visual
Status Display. Locate it within reach of the included
modular cable. Its LEDs should be visible to its
operators. Secure the Visual Status Display to a
surface using its mounting tabs and included pan
head screws or dual lock fasteners.
5. Connect the Visual Status Display to the Dual
Operator Continuous Monitor using the modular
cable.
Figure 4. Visual Status Display features and components
A
B
A
C
Mat Monitor Cord
Dual Operator
Continuous Monitor
Grounded
Worksurface Mat
Power Adapter
Countersunk
Washer
Flat Head Screw
Visual Status Display
Modular Cable
Figure 5. Installing the Dual Operator Continuous
Monitor

TB-3091.E Page 5 of 7 © 2022 DESCO INDUSTRIES INC
Employee Owned
2A Dunhams Lane, Letchworth Garden City, SG6 1BE, United Kingdom • 01462 672005 • Website: DescoEurope.com
6. Secure the ring termination of the white mat monitor
cord to the mat monitor screw post on the right-side
of the Dual Operator Continuous Monitor.
7. Connect the mat monitor cord from the right-side
of the Dual Operator Continuous Monitor to a
grounded worksurface mat. Use the included
countersunk washer and flat head screw to secure
the cord to the grounded mat.
8. Connect the power adapter to the power jack
located on the side of the Dual Operator Continuous
Monitor, and plug the power adapter into the tested
AC outlet.
10 mm Snap Adapters
The 19656 Dual Operator Continuous Monitor includes
interchangeable 10 mm park snaps and 10 mm banana
jack adapters for operators who use wrist cords with
10 mm terminations. Use the park snap's knurled rim
to unscrew the 4 mm park snaps from the monitor and
install the 10 mm park snaps to the monitor. Plug the 10
mm operator jack adapters into the monitor's operator
jacks.
Operation
1. Fit the wristband snugly onto the wrist.
2. Snap the wrist cord to the wristband.
3. Plug the wrist cord into one of the operator jacks.
Its corresponding operator LED will illuminate green
on the Visual Status Display. This indicates that the
operator is properly grounded.
4. If this does not happen, examine the wrist cord for
continuity or damage and the wristband to ensure
that it fits securely. If you have dry skin, apply an
approved dissipative hand lotion such as Menda
Reztore® ESD Hand Lotion.
5. When leaving the workstation, first touch the
monitor's park switch or park snap. The monitor's
audible alarm will disable for approximately 8
seconds. Use this time to disconnect the wrist cord
from the wristband and attach it to the park snap
without sounding a false alarm.
6. Upon returning to the workstation and disconnecting
the wrist cord from the park snap, the monitor will
provide approximately 8 seconds for the operator to
reconnect the wrist cord to a worn wristband before
sounding the monitor's alarm.
Figure 6. Installing the 10 mm snap adapters to the
19656 Dual Operator Continuous Monitor

TB-3091.E Page 6 of 7 © 2022 DESCO INDUSTRIES INC
Employee Owned
2A Dunhams Lane, Letchworth Garden City, SG6 1BE, United Kingdom • 01462 672005 • Website: DescoEurope.com
Calibration
Frequency of recalibration should be based on the
critical nature of those ESD sensitive items handled
and the risk of failure for the ESD protective equipment
and materials. In general, Desco recommends that
calibration be performed annually.
Use the Desco 98221 Wave Distortion Monitor
Verification Tester to perform periodic verification (once
every 6-12 months) of the Dual Operator Continuous
Monitor. The verification tester can be used to check
the test limits of the Dual Operator Continuous Monitor
without removing it from the workstation.
See TB-3074.E for more information.
Figure 7. Using the Dual Operator Continuous Monitor at
a one-person workstation
Figure 9. Parking two wrist cords onto the Dual Operator
Continuous Monitor
Figure 10. Desco 98221 Wave Distortion Monitor
Verication Tester
Figure 8. Using the Dual Operator Continuous Monitor at
a two-person workstation

TB-3091.E Page 7 of 7 © 2022 DESCO INDUSTRIES INC
Employee Owned
2A Dunhams Lane, Letchworth Garden City, SG6 1BE, United Kingdom • 01462 672005 • Website: DescoEurope.com
Specifications
Input Voltage and
Frequency
(External Adapter)
AC/DC Power Adapter
Power Input:
100-240 VAC, 50/60 Hz
Power Output:
9 VDC
Cable Length:
5 ft. (1.5 m)
Operating Temperature 50 to 95° F (10 to 35° C)
Environmental
Requirements
Indoor use only at altitudes
less than 6500 ft. (2 km)
Maximum relative humidity
of 80% up to 85° F (30° C)
decreasing linearly to 50% @
85° F (30° C)
Dimensions
(Monitor)
2.85" L x 5.13" W x 1.11" H
(72 mm x 130 mm x 28 mm)
Dimensions
(Visual Status Display)
3.87" L x 2.08" W x .90" H
(98 mm x 53 mm x 23 mm)
Weight
(Monitor)
0.30 lbs. (0.14 kg)
Weight
(Visual Status Display)
0.11 lbs. (0.05 kg)
Operator Test Range*500 kilohms to 10 megohms
impedance
Worksurface Test
Limit**
10 megohms (±20%)
Operator Test Voltage 1.2 V peak-to-peak @ 1.2 µA,
open circuit
Worksurface Test
Voltage
5 to 7.5 V, open circuit
Alarm Response Time <500 ms
Country of Origin United States of America
*This cannot be verified with standard DC test
equipment. The continuous monitor is an impedance
sensing device, and the limits are determined by the
magnitude and angle of the impedance.
**The worksurface mat must have a conductive
layer such as Dual Layer Rubber or Dissipative
3-Layer Vinyl with conductive buried layers. Desco
workstation monitors are not recommended for use with
homogeneous matting.
ANSI/ESD S20.20 requires the use of a surface
resistance meter for periodic verification of a
worksurface's resistance-to-ground (Rtg). Constant
monitors may not be used as a substitute for this
requirement.
Figure 11. Mounting hole locations on the Dual Operator
Continuous Monitor (all dimensions are in inches)
Limited Warranty, Warranty Exclusions, Limit
of Liability and RMA Request Instructions
See the Desco Europe Warranty -
DescoEurope.com/Limited-Warranty.aspx
Figure 12. Mounting hole locations on the Visual Status
Display (all dimensions are in inches)