Desco 19250 Instruction Manual

TB-2040 12/01 Page 1 of 4

Tester, Combination, 3-State

Operation, Installation and Maintenance

Pass Range 750K - 10M and 750K - 100M

DESCO WEST - 3651 Walnut Avenue, Chino, CA 91710 • (909) 627-8178 • Fax (909) 627-7449

DESCO EAST - 90 Hudson Road, Canton, MA 02021-1407 • (781) 821-8370 • Fax (781) 575-0172 • Web Site: http://www.desco.com

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 is very simple to operate. A green

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.

CAUTION: Use only the AC adapter designed for this unit:

Item 98256 (120 volt) or Item 98257 (220 volt). Using any other

adapters may damage the unit and void the warranty.

Inspection

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 Wall poster

1 5/32" hex wrench

1 9 volt battery

Model numbers 19253 and 19252 are ideally suited for testing foot

grounding devices.

Installation of Model 19250

The Combo Tester may be used as a portable unit, or may be

permanently mounted on either a table or a wall. Please refer to

the following instructions when installing your tester.

Stationary Installation

If you will be using the tester as a portable unit, you may prefer to

mount the unit to a table or wall. Three keyhole slots on the back

of the unit are included to allow you to attach the tester to a

stationary surface.

Figure 2. Mounting hole locations.

1. Select location for mounting Tester. Install three #6 or #8 screws

spaced as illustrated in figure 3, into a wall or other vertical

surface. Make sure that the screw heads do not project out more

than 1/4" from mounting surface. The template on page four is

actual size.

2. Mount the Tester on the screws, pulling down to lock it in place.

TECHNICAL BULLETIN TB-2040

Model Description

19250 Combo Tester, 9 Volt battery

19253 Combo Tester w/ Footplate

19252 Combo Tester w/ Stand

98273 Foot Plate for Combo Tester

98254 Stand for Combo Tester

98256 AC Adapter, 120V

98257 AC Adapter, 220V

Made in America

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DESCO WEST - 3651

DESCO EAST - 90 Hudson Road, Canton,

Figure 3. Stationary installation of the Combo Tester

Operation

The Combo Tester can be operated either on battery or AC power.

The unit comes equipped with a 9 volt alkaline battery. For AC

operation, plug the optional AC adapter into the mini phone jack

located on the upper left hand corner of the tester. AC adapters

are sold separately as item 98256 (120 volt) or 98257 (220 volt).

LOW BATTERY INDICATOR

The Combo Tester includes a low battery indicator alarm circuit. If

both the audible alarm and indicator LED turn on during use,

discontinue testing and replace the battery. The tester will continue

to operate with a weak battery, but results should not be

considered accurate.

The battery can be easily replaced by removing the battery

compartment cover on the back of the unit and installing a new 9

volt battery.

Figure 4. Replacing the battery

General Instructions

In the following test configurations, the 19250 can be used to test

wrist straps while they are worn. Models 19253 and 19252 will

also allow the user to test footwear. Insertion of the banana plug

on the wrist strap cord activates the wrist strap tester circuit and

deactivates the footwear test circuit.

WRIST STRAP TESTING WITH MODEL 19250

This test safely checks that a continuous path between the

operator, wrist strap and ground cord exists.

A. While wearing the wrist strap, plug the banana plug end of the

cord into the jack on the face of the unit.

B. Press rocker switch toward “WRIST CORD”.

C. Press the test button so that the unit activates. Hold down for

2-3 seconds while flexing coil cord area near resistor. Note: Often

the initial intermittency will be failure of strain relief connection to

resistor as simulated by ESD S1.1-1998 paragraph 5.7 Bending

Life Test.

Note: DO NOT TOUCH ANY OTHER METAL WHILE

PERFORMING TEST.

TB-2040 Page 2 of 4

Figure 5. Testing of wrist strap grounding assemblies.

D. Lighting of the green “PASS” LED indicates that the wrist strap

and ground cord assemblies are functioning properly.

E. If either “FAIL LO” or “FAIL HI” LEDs light and the audible

indicator sounds, the wrist strap wearer should check the wrist

strap assembly immediately.

TESTING FOOT GROUNDING DEVICES

In order to test footwear you will need the model 19253 or 19252

Combo Tester. The following instructions are intended for use

while wearing foot grounding devices. When testing conductive

shoes, or foot grounders worn on both feet, test each foot

separately to ensure proper operation and complete protection.

A. Place the Foot Plate on

the floor in front of the Combo

Tester.

B. Plug the plate’s ground

cord into the jack on the left

hand side of the unit.

NOTE: Steps A and B are not

required with the 19252.

Figure 6. Installing ground cord to

“footplate” jack.

C. Press the rocker switch toward “FOOTPLATE”

D. Place one foot on the plate. If the floor is conductive, lift the foot

you are not testing off of the floor during this test. Make sure there

is no cord plugged into the “WRIST CORD” jack.

E. Press the test button so that the

unit activates. Hold for 2-3 seconds

while flexing coil cord area near

resistor.

F. Lighting of the green “PASS”

LED indicates that the foot ground

assemblies are functioning properly.

G. If either red “Fail LO” or red “Fail

HI” LEDs light and the audible

indicator sounds, the wearer should

check the foot grounding device

immediately.

H. Repeat steps C through F with

other foot.

Figure 7. Testing foot

grounding devices with

19253.

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Free Standing Test

Fixture Assembly and

Operation (Model 19252)

The 19252’s rugged steel pedestal

tube is powder coated in a non-

conductive white finish that helps

to prevent false readings if

contacted by skin or loose smocks.

Figure 8. The 19252 Free Standing Test Fixture

Assembly A. Remove 3 screws from baseplate.

B. Position pedestal on the baseplate

with the Tester mounting bracket

pointing away from the operator. Attach

pedestal to baseplate using the three

screws provided. Tighten with hex

wrench provided.

C. Open the compartment and attach

the snap connector to the included 9

volt battery. Attach poster to the wall at

eye level in front of the Tester location.

Figure 9. Attaching pedestal to baseplate

D. Install the Tester on the bracket by aligning keyholes on the

back of tester with mounting studs on bracket. While pushing up

on thumb screw, insert the mounting studs into the keyholes and

slide the tester down. See Figure 10.

E. Twist the thumb screw clockwise to secure the tester to the

bracket.

Figure 10. Installing Tester on bracket and securing Tester to

bracket

WRIST STRAP TESTING

This test verifies that a continuous path between the operator,

wrist strap, and ground cord exists.

A. While wearing the wrist strap, plug the banana plug end of the

cord into the jack on the face of the unit.

B. Press rocker switch toward “WRIST CORD”.

DESCO WEST - 3651 Walnut Avenue, Chino, C

DESCO EAST - 90 Hudson Road,

TB-2040 Page 3 of 4

THUMB SCREW

C. Press the test button so that

the unit activates. Hold down for

2-3 seconds while flexing coil

cord area near resistor.

Note: DO NOT TOUCH ANY

OTHER METAL WHILE

PERFORMING TEST.

D. Lighting of the green “PASS”

LED indicates that the wrist strap

and ground cord assemblies are

functioning properly.

E. If either red “FAIL LO” or

“FAIL HI” LEDs light and the

audible indicator sounds, the

wrist strap wearer should check

the wrist strap assembly

immediately.

TESTING FOOT GROUNDING DEVICES

When testing conductive shoes or heel straps, test each foot

separately to ensure proper operation and complete protection.

A. Press rocker switch toward “FOOTPLATE”.

B. Place one foot on the plate. If the floor is conductive, lift the foot

you are not testing off of the floor during this test. Make sure there

is no cord plugged into the “WRIST CORD” jack.

C. Press the test button so that the unit activates. Hold down for

2-3 seconds while flexing coil cord area near resistor.

D. Lighting of the green

“PASS” LED indicates that

the foot ground assemblies

are functioning properly.

E. If either red “Fail LO” or

red “Fail HI” LEDs light and

the audible indicator

sounds, the wearer should

check the foot grounding

device immediately.

F. Repeat steps A through C

with other foot.

Figure 12. Testing foot grounding devices

Calibration

The models 19250, 19253, and 19252 are calibrated to NIST

traceable standards. We recommend that calibration is performed

annually to ensure that the Tester is operating within limits. Due to

its dual circuit design both test circuits of the Combo Tester must

be calibrated individually.

Desco offers a calibration unit that is specifically designed to

simplify the calibration procedure. This unit is sold as item 07010.

The Calibration Unit comes calibrated to NIST traceable

standards. For additional information on the 07010, ask for

Technical Bulletin TB-2039.

Figure 11. Testing of wrist

strap grounding assemblies

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750 Kilohm - 10 Megohm TEST RANGE - WRIST STRAPS

The following resistance should give the display shown:

Resistance Value (+/- 20%) Test Output

675 Kilohm Red (Fail Lo)

825 Kilohm Green (Pass)

8.5 Megohm Green (Pass)

11.5 Megohm Red (Fail Hi)

Figure 13. Calibration of the Combo Tester’s 750K to 100M range.

750 Kilohm - 100 Megohm TEST RANGE - FOOTWEAR

The following resistance should give the display shown:

Resistance Value (+/- 20%) Test Output

675 Kilohm Red (Fail Lo)

825 Kilohm Green (Pass)

80 Megohm Green (Pass)

120 Megohm Red (Fail Hi)

To calibrate, simply test each resistance value shown above which

are included in the 07010 Calibration Unit. Test across the test

button and “WRIST CORD” jack for calibration of the 750 Kilohm -

10 Megohm range. Test across the test button and “FOOTPLATE”

jack for calibration of the 750K - 100M range. Be sure rocker

switch is set correctly.

Figure 14. Calibration of the Combo Tester 750 Kilohm to 10

Megohm range with the model 07010

Observe the LED’s for the proper response as indicated. Be sure

to hold the cord at an insulated point, so that resistance value is

not affected by the body. Should testing reveal that the Tester is

not functioning properly, verify that the battery or power supply is

operating correctly.

Tester calibration can also be verified with the use of discrete

resistors and two banana-to-alligator cords.

Adjustment

Detailed adjustment instructions are available from the factory.

Unauthorized modifications will void the product warranty.

Servicing should be performed only at the factory. See warranty

section for repair information.

Specifications

Wrist strap circuit

“Hi” Fail Factory set at 11.5 Megohms

“Lo” Fail Factory set at 675 Kilohms

Footground circuit

“Hi” Fail Factory set at 120 Megohms

“Lo” Fail Factory set at 675 Kilohms

General Characteristics

Power 9 volt battery or optional AC power supply

Operation Resistance bridge

Readout Three LED’s & audible alarm

Accuracy ±20%

Weight 12 pounds

Height 39 inches

Consider adding the 19250 to your list of “test equipment [that]

shall be selected to make measurements of appropriate properties

of the technical requirements that are incorporated into the ESD

program plan” as required by paragraph 6.1.3.1 of ANSI/ESD

S20.20.

Limited Warranty

Desco expressly warrants that for a period of one (1) year from the date

of purchase, Desco Combo Testers will be free of defects in material

(parts) and workmanship (labor). Within the warranty period, the product

will be tested, repaired, or replaced at Desco’s option, free of charge. Call

our Customer Service Department at

909-627-8178

(Chino, CA) or 781-

821-8370 (Canton, MA) for a Return Material Authorization (RMA) and

proper shipping instructions and address. Include a copy of your original

packing slip, invoice, or other proof of purchase date. Any unit under

warranty should be shipped prepaid to the Desco factory. Warranty

repairs will take approximately two weeks.

If your unit is out of warranty, call Customer Service at

909-627-8178

(Chino, CA) or 781-821-8370 (Canton, MA) for a Return Material

Authorization (RMA) and proper shipping instructions and address.

Desco will quote repair charges necessary to bring your unit up to

factory standards.

Warranty Exclusions

THE FOREGOING EXPRESS WARRANTY IS MADE IN LIEU OF ALL

OTHER PRODUCT WARRANTIES, EXPRESSED AND IMPLIED,

INCLUDING MERCHANTABILITY AND FITNESS FOR A PARTICULAR

PURPOSE WHICH ARE SPECIFICALLY DISCLAIMED. The express

warranty will not apply to defects or damage due to accidents, neglect,

misuse, alterations, operator error, or failure to properly maintain, clean

or repair products.

Limit of Liability

In no event will Desco or any seller be responsible or liable for any

injury, loss or damage, direct or consequential, arising out of the use of

or the inability to use the product. Before using, users shall determine

the suitability of the product for their intended use, and users assume all

risk and liability whatsoever in connection therewith.

DRILL PATTERN

FOR

COMBO TESTER

ACTUAL SIZE

TB-2040 Page 4 of 4

DESCO INDUSTRIES INC.

Employee Owned

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