Fluke 941 User manual

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941
Light Meter
Users Manual
English
PN 3409850
January 2009
© 2009 Fluke Corporation, All rights reserved. Printed in China. Specifications
are subject to change without notice. All product names are trademarks of
their respective companies.

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LIMITED WARRANTY AND LIMITATION OF LIABILITY
Each Fluke product is warranted to be free from defects in material and
workmanship under normal use and service. The warranty period is one year and
begins on the date of shipment. Parts, product repairs, and services are warranted
for 90 days. This warranty extends only to the original buyer or end-user customer
of a Fluke authorized reseller, and does not apply to fuses, disposable batteries,
or to any product which, in Fluke’s opinion, has been misused, altered, neglected,
contaminated, or damaged by accident or abnormal conditions of operation or
handling. Fluke warrants that software will operate substantially in accordance
with its functional specifications for 90 days and that it has been properly recorded
on non-defective media. Fluke does not warrant that software will be error free or
operate without interruption.
Fluke authorized resellers shall extend this warranty on new and unused products
to end-user customers only but have no authority to extend a greater or different
warranty on behalf of Fluke. Warranty support is available only if product is
purchased through a Fluke authorized sales outlet or Buyer has paid the applicable
international price. Fluke reserves the right to invoice Buyer for importation costs of
repair/replacement parts when product purchased in one country is submitted for
repair in another country.
Fluke’s warranty obligation is limited, at Fluke’s option, to refund of the purchase
price, free of charge repair, or replacement of a defective product which is returned
to a Fluke authorized service center within the warranty period.
To obtain warranty service, contact your nearest Fluke authorized service center
to obtain return authorization information, then send the product to that service
center, with a description of the difficulty, postage and insurance prepaid (FOB
Destination). Fluke assumes no risk for damage in transit. Following warranty repair,
the product will be returned to Buyer, transportation prepaid (FOB Destination).
If Fluke determines that failure was caused by neglect, misuse, contamination,
alteration, accident, or abnormal condition of operation or handling, including
overvoltage failures caused by use outside the product’s specified rating, or normal
wear and tear of mechanical components, Fluke will provide an estimate of repair
costs and obtain authorization before commencing the work. Following repair, the
product will be returned to the Buyer transportation prepaid and the Buyer will be
billed for the repair and return transportation charges (FOB Shipping Point).
THIS WARRANTY IS BUYER’S SOLE AND EXCLUSIVE REMEDY AND IS IN LIEU OF
ALL OTHER WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO
ANY IMPLIED WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR
PURPOSE. FLUKE SHALL NOT BE LIABLE FOR ANY SPECIAL, INDIRECT, INCIDENTAL,
OR CONSEQUENTIAL DAMAGES OR LOSSES, INCLUDING LOSS OF DATA, ARISING
FROM ANY CAUSE OR THEORY.
Since some countries or states do not allow limitation of the term of an implied
warranty, or exclusion or limitation of incidental or consequential damages, the
limitations and exclusions of this warranty may not apply to every buyer. If any
provision of this Warranty is held invalid or unenforceable by a court or other
decision-maker of competent jurisdiction, such holding will not affect the validity or
enforceability of any other provision.
Fluke Corporation
P.O. Box 9090
Everett, WA
98206-9090
U.S.A.
Fluke Beijing Service Center
Rm. 401 SCITEC Tower
Jianguomenwai Dajie
Beijing 100004, PRC
Hot Line: 400.810.3435
Fax: [phone]
11/ 99
To register your product online, visit http://register.fluke.com

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➊Light sensor
➋Display(LCD)
➌Lux / foot candles
➍MAX Lock up MIN and MAX value
➎Power Button: ON/OFF
➏Manual range selection
➐DATA HOLD button
➑AUTO ranging
➒Light sensor Zero Adjustment
MAX MIN
HOLD
LUX
FC
1
2
6
7
9
8
3
4
5

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Fluke-941
Light Meter
CONTENTS
Symbols................................................................................................................. 5
Unpacking and Inspection................................................................................... 5
Introduction.......................................................................................................... 5
Operation ............................................................................................................ 5
Lx / Fc ............................................................................................................... 5
Data Hold ....................................................................................................... 5
AUTO / MAN Ranging..................................................................................... 6
MIN/MAX ........................................................................................................ 6
Auto-Power Off .............................................................................................. 6
Zero.................................................................................................................. 6
Specifications ....................................................................................................... 6
Maintenance and Repair .................................................................................... 7
Battery Replacement ..................................................................................... 8

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SYMBOLS
Caution! Refer to the
explanation in this
Manual
Warning and Precautions
Do not operate the meter in explosive gas (material), combustible gas•
(material) steam or filled with dust.
The light sensor is calibrated to CIE standard incandescent lamp at 2854 °K•
and may give different readings for spectrums from other lamp types.
UNPACKING AND INSPECTION
Your shipping carton should include:
1 941 light meter
1 9 volt battery
1 Users Manual
If any of the items are damaged or missing, return the complete package to
the place of purchase for an exchange.
INTRODUCTION
The 941 measures the visible light from fluorescent, metal halide, high-
pressure sodium or incandescent sources.
One LUX (Lumen) is the illumination from a one candela lamp perpendicular to
a surface one meter squared at a distance of one meter. One foot-candle (Fc) is
the illumination from a one candela lamp perpendicular to a surface one foot
squared at a distance of one foot.
OPERATION
Press the1. button to turn power on or off
Remove sensor cap and place the sensor perpendicular to the light.2.
Select Illuminance scale and range for reading.3.
When done testing, replace the sensor cover to protect the filter and4.
sensor.
Lx / Fc
Illuminance scales. 1 foot-candle = 10.764 Lux and 1 lux = 0.09290 foot-
candles.
Data Hold
Freezes the reading present on the LCD at the moment the button is pressed.
Press HOLD again to disable Data Hold.

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AUTO / MAN Ranging
Press the AUTO or MANual ranging button for useable reading. AUTO
ranging is the default operation.
MIN/MAX
Pressing the MIN/MAX button for less than 1 second will put the meter into
a mode of displaying the maximum, minimum, or actual readings. Each time
the MIN/MAX button is pressed, the meter will cycle from MAX MIN off.
Select the proper measurement range before enabling the MIN/MAX feature.
Auto-Power Off
In order to save battery life, your light meter powers down automatically
after approximately 6 minutes of inactivity. You can turn it back on by
pressing the button. You can disable Auto Power Off by pressing and
holding the HOLD button while turning the meter ON.
Zero
The light sensor will change the null point over time. To reset the null point,
cover the sensor, press the ZERO button. The display will show “ADJ”. When
the null reset is done, the display will read ‘00.0’.
SPECIFICATIONS
General:
Sampling Rate: 2.5 times per second for digital display.
Display: 3½ digit, 1999 count LCD
Sensor: Silicon photodiode and filter.
Environment: Indoor operation
Altitude: Up to 2000m.
Temperature / Humidity:
Operating: -10°C to 50°C, 0 to 80% RH.
Storage: -10°C to 50°C, 0 to 70% RH.
Power Supply: 9V NEDA 1604, IEC 6LR61
Battery life: 200 hours
Auto Power Off: approx 6 min
Dimension (Base): 130 x 63 x 38 mm (5.1 x 2.5 x 1.5”)
Dimension (Sensor): 80 x 55 x 29 mm (3.2 x 2.2 x 1.1”)
Weight: 220 g (.48 lb.) include battery

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Illumination:
Measuring Range: 20, 200, 2000, 20000, 200000 Lux
20, 200, 2000, 20000 Foot candles
Accuracy: ± 3% (Calibrated to standard
incandescent lamp at 2854°K)
± 6% other visible light sources
Angle deviation from cosine
Characteristics
30° ± 2%
60° ± 6%
80° ± 25%
Cosine Angular corrected per JIS C 1609:1993 and CNS 5119 general A class
specifications.
MAINTENANCE AND REPAIR
If there appears to be a malfunction during the operation of the meter, the
following steps should be performed in order to isolate the cause of the
problem.
Check the battery. Replace the battery immediately when the symbol1.
“” appears on the LCD.
Review the operating instructions for possible mistakes in operating2.
procedure.
Except for the replacement of the battery, repair of the meter should be
performed only by a Factory Authorized Service Center or by other qualified
instrument service personnel. The front panel and case can be cleaned with
a mild solution of detergent and water. Apply sparingly with a soft cloth and
allow to dry completely before using. Do not use aromatic hydrocarbons or
chlorinated solvents for cleaning.

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Battery Replacement
Turn off the meter and slide out the battery cover. Replace the battery1.
with a NEDA type 1604 or equivalent 9V alkaline battery. Replace the
cover.
Remove battery when the Fluke-941 is not used for extended period.2.
Battery Replacement
OPEN