EXTECH 461830

User's Guide
Digital Stroboscope Tachometer
Model 461830 and Model 461831
EXTECH INSTRUMENTS CORPORATION warrants this instrument to be free of defects
in parts and workmanship for one year from date of shipment (a six month limited
warranty applies on sensors and cables). If it should become necessary to return the
instrument for service during or beyond the warranty period, contact the Customer
Service Department at (781) 890-7440 ext. 210 for authorization or visit our website at
www.extech.com (click on ‘Contact Extech’ and go to ‘Service Department’ to request an
RA number). A Return Authorization (RA) number must be issued before any product is
returned to Extech. The sender is responsible for shipping charges, freight, insurance
and proper packaging to prevent damage in transit. This warranty does not apply to
defects resulting from action of the user such as misuse, improper wiring, operation
outside of specification, improper maintenance or repair, or unauthorized modification.
Extech specifically disclaims any implied warranties or merchantability or fitness for a
specific purpose and will not be liable for any direct, indirect, incidental or consequential
damages. Extech's total liability is limited to repair or replacement of the product. The
warranty set forth above is inclusive and no other warranty, whether written or oral, is
expressed or implied.
Congratulations on your purchase of the Extech Digital Stroboscope Tachometer. This
device measures the speed of moving parts such as gears, fans, propellers, centrifuges,
and pumps. The stop-motion action of this instrument permits the visual inspection of
moving parts. Careful use of this instrument will provide years of reliable service.
Model 461830/461831 Version 2.2 November 2003
This symbol, adjacent to another symbol or terminal, indicates the user must refer
to the manual for further information.
This symbol, adjacent to a terminal indicates that, under normal use, hazardous
voltages may be present
WARNING: Do not look directly at the Strobe’s Xenon lamp or its reflector.
WARNING: This device causes moving objects to appear still. Take precautions against
accidental contact with moving objects.
CAUTION: Do not touch the flash tube.
Model 461830/461831 Version 2.2 November 2003
General Specifications
Exclusive one-chip LSI circuit with crystal time base
4-digit (10,000 count; 0 to 9999) LED display
Measurement unit
RPM (revolutions or rotations per minute) is the speed of the
moving device under test which equals the FPM rate (strobe
flashes per minute)
Operating Temperature
32 to 122 F (0 to 50 C)
Operating Humidity
< 80% RH
Power Supply
110VAC (461830) or 220VAC (461831) 50/60Hz ±10%
Power Consumption
<25 watts @ 115V
2.2 lbs. (1kg)
8.3 x 4.8 x 4.8" (21 x 12 x 12cm)
Housing construction
Impact resistant plastic with plastic lens and mirrored reflectors
Electrical Specifications
Measurement Range
100 to 10,000 RPM/FPM
0.1 (<1000 RPM/FPM)
1 (1000 to 9999 RPM/FPM)
10 (10,000 RPM/FPM)
± (0.05% + 1 digits)
Sampling Time
1 second
Strobe Flash adjust range
LOW: 100 to 1,000 RPM/FPM
HIGH: 1000 to 10,000 RPM/FPM
Strobe Flash tube type
Xenon lamp
Strobe Flash duration
60 to 1000 microseconds
Strobe Flash Energy
4 Watt-Seconds (Joules)
Strobe Beam Angle
Strobe Flash Color
White 6500 K
Notes: Replace the Xenon lamp when readings appear irregular. To prolong the Xenon lamp
life and ensure safe operation, please adhere to the following recommendations.
A 30-minute use limit < 3000rpm and 5-minute use limit > 3000rpm exists. Do not use
the instrument for periods longer than specified otherwise damage to the instrument
may result.
Always permit a 10-minute cool-down between cycles.
Do not touch the Xenon flash tube.
Model 461830/461831 Version 2.2 November 2003
Meter Description
Xenon lamp
LED Display
FINE adjust knob
Power ON/OFF switch
Grip handle
Range Select Switch
COARSE adjust knob
AC power cord and jack
Model 461830/461831 Version 2.2 November 2003
Powering the instrument
1. Plug the supplied power cable into the instrument’s power cable jack.
2. Plug the other end of the cable into an appropriate AC power source. The Model
461830 requires 110VAC and the 461831 requires 220VAC. Do not plug the device
into an incorrect power source otherwise damage to the instrument will result.
3. Use the ON/OFF switch to turn the instrument on or off.
Speed (RPM) Measurements
1. Remove power to the device under test so that it is stationary.
2. Affix a reflective mark or place a small piece of the supplied reflective tape on the
device under test.
3. Point the Stroboscope’s beam toward the reflective mark.
4. Use the ‘FINE’ and ‘COARSE’ adjustment knobs to synchronize or "stop" the motion of
the reflective mark (read the ‘Display Notes’ section below).
5. Read the RPM value on the LED display.
Range Adjustments
1. While measuring, use the RANGE button to select the range as desired
2. The LOW range is used for measurements below 1,000 RPM. The HIGH range is used
for measurements above 1,000 RPM.
Model 461830/461831 Version 2.2 November 2003
Display Notes for Speed Measurements
Care must be taken to ensure that the reflective mark is providing a 1:1 measurement.
Check that there is only one mark and not two, four, or more stationary marks on the object
under test.
Two or more stopped marks indicate a ‘harmonic’ measurement (2:1, 3:1, 4:1 etc.) and the
instrument will display double, triple, or quadruple the actual speed. A useful method of
avoiding harmonic measurements is to adjust the FINE/COARSE knobs until two images
(reflective marks) appear and then lower the flash rate (via COARSE/FINE knobs) until a
single, stationary image appears. This will be the actual speed.
In the example below, a rotating shaft is affixed with one piece of reflective tape. The
illustrations below represent several possible images that would appear when the strobe
beam is pointed to the shaft.
If more than one reflective mark appears (as in columns 3, 4, and 5 below) the image is
showing a ‘harmonic’. The bold column (column 2) shows the actual speed of the shaft.
Column 1 shows a harmonic whereby the actual speed is divided in half. Because of this, it
is good practice to adjust the ‘FINE’ and ‘COARSE’ knobs until you can see the ‘doubled
harmonic’ (Column 3) and then the ‘halved harmonic’ (Column 1) and then find the setting
in-between (Column 2 in bold).
Shaft speed
Strobe flash rate
Visible reflective
Note that the LED display has an AUTO RANGE INDICATOR (flashing decimal at the far
right) that appears when the readings are over 10,000 RPM. In these cases, multiply the
displayed reading by 10.
Visually inspecting a moving object (stop-motion)
When the speed of the moving object matches the flash rate of the stroboscope, the
moving object appears still. Measure the speed of a moving object as described in the
previous sections to obtain a stop-motion. Once stop-motion is achieved, the FINE adjust
knob is used to vary the viewing perspective of the object under test for visual inspection.
Important note on Test Durations
The Xenon lamp used in this instrument has time restrictions on usage. If the specified test
times and cool-off periods (shown in the table below) are not observed, damage to the
instrument can result and the life span of the lamp can be shortened.
Max. Operating Time
< 3,000 rpm
30 minutes
> 3,000 rpm
5 minutes
Cool-Off Time
10 minutes
Model 461830/461831 Version 2.2 November 2003
Calibration and Repair Services
Extech offers repair and calibration services for the products we sell. Extech also provides
NIST certification for most products. Call the Customer Service Department for information
on calibration services available for this product. Extech recommends that annual
calibrations be performed to verify meter performance and accuracy.
Support Hotline (781) 890-7440
Tech support: Ext. 200; Email: [email protected]
Repair/Returns: Ext. 210; Email: [email protected]
Website: www.extech.com
Copyright © 2003 Extech Instruments Corporation
All rights reserved including the right of reproduction in whole or in part in any form.
Model 461830/461831 Version 2.2 November 2003