Desco 19250 Technical Bulletin

Combo Wrist Strap / Footwear Tester
Installation, Operation and Maintenance
Pass Range 750K - 10M and 750K - 100M
Figure 1. Desco 19250 Combo Tester
Description
The Desco 19250 Combo Tester is a 3-state touch tester
designed for fast, frequent testing of ESD personnel grounding
devices. This product can be used as one of the tools to fulfill the
ANSI ESD S20.20 paragraph 6.1.3.2 "Compliance Verification
Plan. Verification should include routine checks of the Technical
Requirements of the Plan." The Combo Tester incorporates a
unique dual test circuit design which improves accuracy of testing
and eliminates the need for separate wrist strap and foot grounder
test units. The 19250 is equipped with a 750 kilohm - 10 megohm
circuit, ideal for testing of wrist straps and a 750 kilohm - 100
megohm circuit designed for accurate testing of footwear.
Test parameters are factory set but can be adjusted to match your
own specifications. The 19250
light signals the user that everything is OK. A red light and an
audible indicator means that the circuit resistance is either too low
or too high.
The Tester operates on either a 9 volt battery or a special AC
adapter. The Combo Tester is calibrated to NIST traceable
standards and is available in three models.
Model Description
19250 Combo Tester, 9 Volt battery
19253 Combo Tester w/ FOOT PLATE
19252 Combo Tester w/ Stand
19261 Combo Tester Mounting Plate
98273 Foot Plate for Combo Tester
98254 Stand for Combo Tester
98256 AC Adapter, 120V
98257 AC Adapter, 220V
CAUTION: Use only the AC adapter designed for this unit:
Item 98256 (120 volt) or Item
adapters may damage the unit and void the warranty.
Per ESD Handbook ESD TR20.20 paragraph 5.3.2.4.4 Test
Frequency "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
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TECHNICAL BULLETIN TB-2040
is very simple to operate. A green
98257 (220 volt). Using any other
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a continuous, reliable ground is needed, and then continuous
monitoring should be considered or even required."
Per ESD SP9.2 APPENDIX B - Foot Grounder Usage Guidance
"Compliance verification should be performed prior to each use
(daily, shift change, etc.). The accumulation of insulative materials
on the FCS may increase the foot grounder system resistance. If
foot grounders are worn outside the ESD protected area testing for
functionality before reentry to the ESD protected area should be
considered."
Per ESD SP9.2 APPENDIX C -Parallel Ground Paths
"A parallel ground path allows a flow of electrical current through a
path that is not intended for the test. Parallel ground paths may be
caused by several different situations.
For example:
a. The path represented by the person standing with one shoe on
the floor and the other shoe on the test apparatus. A parallel
path may be created by the shoe on the floor. Current from the
test instrument is then directed down two paths when it was
intended to be directed down one. The correct path for the test
is with one shoe in the air or on an insulating surface and the
other shoe on the test plate.
b. The path presented by a person inadvertently supporting
themselves by means of one hand on another object such as
a wall, table or supporting member in order to measure the
resistance in one foot contact. The hand has created a parallel
path to ground.
c. The path represented by a person leaning against another
object with other parts of the body in order to provide physical
support during a testing sequence. This can then lead to other
grounding paths and erroneous results."
Packaging
Remove the Tester from the carton and inspect for damage.
Items included with model 19250:
1 Combo Tester
1 9 volt battery
Items included only with model 19253:
1 Combo Tester
1 Foot plate
1 Ground cord
1 9 volt battery
Items included only with model 19252:
1 Combo Tester
1 Base plate
1 Pedestal tube with bracket and boot installed
1 4" banana plug connector
1 Vinyl insulator cap
1 Wall poster
1 5/32" hex wrench
1 9 volt battery
Model numbers 19253 and 19252
grounding devices.
Made in the
United States of America
are ideally suited for testing foot
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