Extech Instruments 461750 User manual

User Manual
Mini Contact Tachometer
Model 461750

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Introduction
Congratulations on your purchase of the Extech Tachometer.
The Model 461750 Contact Tachometer uses convex and concave attachments to measure
RPM. It also has a built-in wheel to measure the linear surface speed of moving devices such as
conveyors and treadmills. Careful use of this tachometer will provide years of reliable service.
Meter Description
1. RPM adaptor
2. Wheel for linear surface measurements
3. Adaptor shaft
4. Adapter socket
5. Hand Guard
6. Power ON/OFF and HOLD button
7. Unit of measure selection button
8. LCD Display
9. Alternate Power ON/OFF button
Note that the battery compartment is located
on the rear of the instrument
Display Description
1. Low Battery
2. Data Hold
3. Rotations per minute
4. Meters per minute
Feet per minute
Yards per minute

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Safety Precautions
The 461750 incorporates a finger guard for protection. However, care should be taken when
measuring surface speed to avoid injury.
1. Hold the meter firmly when touching the wheel or attachment to a moving object
2. Keep fingers behind the finger guard while taking measurements
3. Keep your eyes and attention on the measurement activity at all times
4. Do not attempt to record measurements while holding the meter to the moving object (use the
Data Hold feature to freeze the reading on the LCD; refer to the Data Hold section of this
manual).
Meter Power
Power ON / OFF
1. Press the triangular POWER HOLD button to turn the device ON. Alternatively, press the button
at the bottom of the meter (just under the LCD) which doubles as a power on/off button. Two
buttons are provided for easy reach at any holding angle.
2. Press and hold the triangular POWER HOLD button (or the alternate button) for approx. 5
seconds to turn the device OFF.
Auto Power OFF
1. The meter turns off AUTOMATICALLY after 20 minutes.
2. For 461750 only: To disable this feature, turn the meter off. Then press and hold the POWER
and UNITS buttons until the meter turns on. Release the POWER button first and the ‘n’ display
icon will appear. This indicates that the feature is disabled.
Never dispose of used batteries or rechargeable batteries in household waste.
As consumers, users are legally required to take used batteries to appropriate
collection sites, the retail store where the batteries were purchased, or wherever
batteries are sold.
Disposal: Do not dispose of this instrument in household waste. The user is obligated to
take end-of-life devices to a designated collection point for the disposal of electrical and
electronic equipment.

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Measurements
RPM Measurements
Contact Tachometer
1. Affix the convex (cone) or concave (funnel) attachment that best fits the application to the
meter shaft as shown below.
2. Turn the meter ON.
3. Use the UNITS button to select RPM (the display will reflect the selection).
4. Touch the attachment to the moving object and read the displayed measurement.
Rotating
Wheel
Touch the convex or
concave attachment
to the turning object

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Surface Speed Measurements
1. Turn the meter on as described previously.
2. Touch the wheel to the moving object and read the measurement on the display. Refer to
diagram below.
3. Use the UNITS button to select the unit of measure: ft/min (feet per minute); m/min (meters per
minute); yds/min (yards per minute).
Data Hold Feature
After the meter is turned on, the POWER-HOLD button can be pressed and released to activate
Data Hold. Data Hold automatically freezes the displayed reading. While the reading is held, the
HOLD display icon switches on. Press the POWER-HOLD button again to exit this mode.
Maintenance
Battery Replacement
When the 9V battery weakens, the low battery indicator appears on the LCD. To replace the battery,
open the rear compartment and exchange the battery. Be sure to replace the compartment cover
securely prior to meter use.
Meter Cleaning
Wipe the meter housing with a damp cloth only. Do not use any abrasives or solvents.
Conveyor
belt
Touch wheel to moving belt

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Specifications
General Specifications
Display 5-digit LCD Display
Range selection Automatic range selection
Time Base 4MHz Quartz Crystal
Sampling Time 1 second (>60 rpm); >1 second (10 to 60 rpm)
Operating Temperature 32 to 122oF (0 to 50oC)
Operating Humidity 80% RH Max.
Power supply 9V Battery
Battery Life 40 hours (approx.)
Applicable standards EN 50081-1/1992 (EN 55022)
EN 50082-1/1997 (EN 55024)
Dimensions 5.9 x 2.0 x 1.3” (150 x 51 x 33mm)
Weight 5.0 oz. (142g)
Range Specifications
Measurement
Range
Accuracy
Rotation
10.000 to 9999 rpm
± (0.1% reading + 2 digits)
Surface Speed
3.0000 to 6560.0 ft/min
± (1.5% reading + 2digits)
Surface Speed
1.0000 to 1999.9 m/min
± (1.5% reading + 2digits)
1.0000 to 5000.0 yds/min

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Two-year Warranty
Teledyne FLIR LLC warrants this Extech brand instrument to be free of defects in parts and workmanship for
two years from date of shipment (a six-month limited warranty applies to sensors and cables). To view the full
warranty text please visit: http://www.extech.com/support/warranties.
Calibration and Repair Services
Teledyne FLIR LLC offers calibration and repair services for the Extech brand products we sell. We
offer NIST traceable calibration for most of our products. Contact us for information on calibration
and repair availability, refer to the contact information below. Annual calibrations should be
performed to verify meter performance and accuracy. Product specifications are subject to change
without notice. Please visit our website for the most up-to-date product information:
www.extech.com.
Contact Customer Support
Customer Support Telephone List: https://support.flir.com/contact
Calibration, Repair, and Returns: [email protected]
Technical Support: https://support.flir.com
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All rights reserved including the right of reproduction in whole or in part in any form
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