General LT2234C User manual
TABLE OF CONTENTS
Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
Key Features. . . . . . . . . . . . . . . . . . . . . . . . 4
Safety Instructions. . . . . . . . . . . . . . . . . . . 4
What’s in the Case . . . . . . . . . . . . . . . . . . . 4
Product Overview. . . . . . . . . . . . . . . . . . . . 5
Setup Instructions . . . . . . . . . . . . . . . . . . . 6
Operatin Instructions. . . . . . . . . . . . 6 – 10
Makin rpm Measurements . . . . . . . 6 –7
Storin and Recallin . . . . . . . . . . . 8 – 10
Measurements
Specifications . . . . . . . . . . . . . . . . . 11 – 12
Maintenance Tips. . . . . . . . . . . . . . . . . . . 12
Warranty Information. . . . . . . . . . . . . . . . 13
Return For Repair Policy . . . . . . . . . . . . . 14
2
INTRODUCTION
Thank you for purchasing General Tools & Instruments’ Model
LT2234C Non-Contact Tachometer. Please read this user’s
manual carefully and thoroughly before using the instrument.
The LT2234C is a general-purpose handheld instrument that
can measure the rotational speed of a motor’s or generator’s
spinning shaft. It does so by bouncing a laser beam off a
piece of reflective tape affixed to the shaft and using an in-
tegrated photocell to count the number of reflections pro-
duced per minute. Measurements are displayed in real time
on a 0.7-in. (18mm) high backlit liquid-crystal display and
stored in memory. Up to 96 measurements of rpm can be
stored, indexed and recalled, along with the last value, the
minimum value and the maximum value of a series. Thanks
to its five-digit display and the use of a non-contact meas-
urement technique, the tachometer can measure the speeds
of shafts spinning at up to 99,999 rpm.
The LT2234C is powered by three “AAA” batteries (included).
3
KEY FEATURES
• Uses non-contact measurement technique and
autoranging
• Wide measurement range and high resolution
• Backlit 0.7-in. high display supports work in low light
• Stores and indexes up to 96 measurements
• Memorizes the last, minimum and maximum values
of a series of measurements
• One-handed operation
• Automatically powers off when not measuring,
extending battery life
• Durable ABS plastic housing
SAFETY INSTRUCTIONS
Spinning shafts and fast-moving belts can be dangerous. When
using the tachometer, take care not to let your fingers, hands,
hair or clothing make contact with moving parts.
WHAT’S IN THE CASE
The LT2234C comes fully assembled in a hard carrying case
along with fresh batteries, two 24 in. (600mm) long strips of
1/2 in. (12mm) wide adhesive reflective tape and this user’s
manual.
4
PRODUCT OVERVIEW
Figure 1 shows all of the controls and indicators and other
physical features of the LT2234C. Familiarize yourself with
their positions before moving on to the setup procedure.
Fi . 1. The LT2234C’s controls and indicators and other
physical features
1-1 Reflective tape (on spinning shaft)
1-2 Reflected laser light (to internal photosensor)
1-3 Five-digit liquid-crystal display
1-4 Measure button
1-5 MEM button
1-6 Battery compartment cover (on back)
5
SETUP INSTRUCTIONS
INSTALL BATTERIES
Install the three “AAA” batteries that came with the instru-
ment in its battery compartment. To open the compartment,
remove the Phillips head screw holding its cover (callout
1-6) in place and slide it away. When installing the batteries,
use the + and – marks stenciled inside the battery compart-
ment to position them correctly.
OPERATING INSTRUCTIONS
MAKING RPM MEASUREMENTS
To measure the rotational speed of a motor/generator shaft:
1. Identify the tar et. Determine whether there is a larger
surface to measure than the shaft itself. If some thing with
a larger diameter (for example, a fan or a wheel of any
type) is attached to the shaft, use any flat part of its surface
as the measurement target instead.
2. Prepare the tar et. Either unplug the generator/motor or
make sure that it cannot be turned on remotely or turn on
automatically. Scrape the target area clean enough so a
piece of tape will stick to it. If the target area is naturally
reflective, cover it with black tape or paint.
3. Attach reflective tape to the tar et. Cut a 1/2 in. square
piece of reflective tape, remove its backing, and apply it to
the target area.
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4. Make the measurement. Turn on the motor or generator.
Cradling the tachometer in your right hand, move it as
close to the shaft as possible, but no closer than 2 inches
away. Position the instrument so its main axis is aligned
with the end of the shaft. Using your right thumb, press the
Measure button (callout 1-4) while shining the red laser
beam on the reflective tape. Confirm that the tachometer
is receiving a signal by checking that the (()) Monitor Indi-
cator icon flashes on the display each time the beam hits
the moving tape. When the display reading stabilizes,
release the Measure button.
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TWO MEASUREMENT TIPS
1. If your motor/ enerator’s shaft spins slowly (i.e.,
at less than 50 rpm), getting an accurate reading
may require placing one or more additional squares
of reflective tape on the target. Begin by adding a
second square of tape on the circumference of the
target 180º from the first square (at 6 o’clock rela-
tive to 12 o’clock). Then perform Step 4 above, but
divide the display reading by two to account for the
presence of the second square. If the result is still
unsatisfactory, add another two pieces of tape at
3 o’clock and 9 o’clock and perform Step 4, but now
divide the display reading by four.
2. If bri ht ambient li ht is preventin the
LT2234C from receiving the reflected beam, try
shading the target.
STORING AND RECALLING
MEASUREMENTS
The LT2234C can store up to 96 measurements of rpm and
recall them in the order in which they were made and stored.
Individual measurements or series of measurements can only
be stored while the Measure button is pressed and held.
When the Measure button is released, the contents of the in-
strument’s memory are frozen. When the Measure button is
pressed again, the memory’s contents are erased.
To store an individual measurement, press the MEM button
(callout 1-5) before releasing the Measure button.
To store a series of measurements, press the MEM button
after each measurement. Remember not to release the Meas-
ure button until you have completed storing the entire series
of measurements.
To recall an individual measurement, press the MEM but-
ton once and hold it. The display will show the last measure-
ment stored—unless the Measure button was pressed in the
interim.
To recall a series of stored measurements, you have three
options.
1. One is to press the MEM button once and hold it. Doing
so will illuminate the display, which will show the highest
of the measurements stored in mem-
ory, along with the word “UP”. Note
that if you continue holding the MEM
button, the display will alternate be-
8
tween showing the highest value and “UP”. Also note that
releasing the MEM button powers off the display and the
instrument.
2. The second option is to press the MEM
button twice and hold it. Doing so again
illuminates the display, but now it
shows the last reading you stored, in-
dicated by and alternating with the letters “LA”.
3. The third option is to press the MEM
button three times and hold it. Doing so
retrieves the slowest of the measure-
ments you have stored. This value is
shown alternating with the letters “dn”, signifying the min-
imum speed.
To try out other memory-related features, first push the
Measure button on the right side. Then press the MEM button
once, twice and three times (holding it in each time) and note
from the display that all of your stored measurements have
been erased (indicated by “0.0” readings for UP, dn and LA).
You can confirm this by pressing and holding the MEM button
until the display begins counting down from 20. When the
count reaches 0, the display immediately switches to show-
ing the letters “AN” on the left side and a number (in this
case, “0”) on the right. (The letters “AN” are an abbreviation
for the Ancient Greek word for “recall.”)
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To complete your understanding of the tachometer’s memory
function, make and store a set of five rpm measurements,
remembering not to push the Measure button until you are
finished. Then press and hold the MEM button as many times
as needed to make the display go into countdown mode.
Note that because you have stored five measurements, the
display will read “AN 5” once the countdown reaches zero. If
you release the MEM button and then press and hold it again,
the display will first read “1” and then the value of the first
of the five measurements you stored. If you release the MEM
button and then press and hold it again, the display will then
show “2”, followed by the value of your second measure-
ment. Release, press and hold again, and the display will
show “3”, followed by the value of your third measurement.
By repeating this sequence, you can retrieve up to 96 meas-
urements in the order in which they were stored. Once all of
the stored measurements have been displayed, the tachome-
ter will return to the mode in which pushing the MEM button
once, twice or three times calls up the minimum, maximum
and last values of the set of measurements you have stored.
10
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