Monarch Instrument Nova-Strobe BA - Manual (Page 6)

For example, when viewing a shaft with a single key way you will see one stationary image of the key way at the actual speed and at 1/2,1/3,1/4, etc, of the actual speed.
Y
ou will see 2 images of the key
way at 2 times the actual speed, 3 key way at 3 times, etc. The FPM equals the shafts Revolutions Per Minute (RPM) at the highest flash rate that gives only one stationary image of the key way
.
If the speed is outside the full scale range of the stroboscope (8,000 FPM), it can be measured using the method of harmonics and multipoint calculation. Start at the highest flash rate and adjust the flash rate down.
Y
ou will encounter multiple images so be aware of these. Note the flash rate of the first
SINGLE image you encounter, call this speed “A”. Continue decreasing the flash rate until you encounter a second SINGLE image. Note this speed as “B”. Continue decreasing the speed until you reach a third SINGLE image at speed “C”. For a two point calculation the actual speed is given by:
RPM =
AB/(A-B)
For a three point calculation:
RPM = 2XY(X+Y)/(X-Y)
2 where
X = (A-B) and Y = (B-C)
In instances when you can shut down the device and install a piece of reflective tape, then an optical tachometer is easier to use for RPM measurement.
St
roboscopes must be used when you can’t
shut down the device.
The human eye is not easily tricked into seeing a stopped image by a
stroboscope when the flash rate is slower than 300 FPM. Therefore, stroboscopes are just about impossible to use below 300 FPM for inspection or to measure RPM.
6.0 LAMP
AND FUSE REPLACEMENT
6.1 Lamp Replacement (L-1902) W
ARNING:
B
e
fore attempting to remove the lamp, make sure the stroboscope
is turned off and any mains cord removed from the ac outlet. Allow the lamp to cool, waiting at least 1 minute.
The stroboscope is designed to discharge the internal high voltages within 30 seconds. How- ever, caution should be exercised when replacing the lamp. The lamp can be replaced by using only a pocket screwdriver
. It is not necessar
y to r
emove
any scr
ews to r
eplace the lamp.
A
spare lamp is supplied with each new BB and BA
S
trobe
Kit or can be ordered separately
.
To
change the lamp:
1.
Push apart the two tabs on the side of the reflector housing and remove the front lens using
a small screwdriver to help pry one tab and lift the lens.
T
ake care not to pry the tab any
more than is necessary to free the lens. The reflector is held in place by the front lens and will come loose, but is not necessary to remove the reflector
.
3
Stopped
Image
1/4 times
1/2 times
1
time
2 times
3 times
4 times
Flash Rate (FPM)
5
0
0
1000
2000
4000
6000
8000
Figure 1 Object Rotating at 2000 FPM
2.
Hold the lamp with a cloth between your forefinger and thumb and rock it back and forth
gently while pulling out.
Do not attempt to rotate the lamp.
The lamp is socketed and
will come out easily when pulled.
W
ARNING:
D
o
NOT touch the new lamp with bare fingers.
3.
The lamps are polarized and must be put into the socket matching polarity
.
Using a lint
free cloth, match up the red dot on the plug with the red dot on the socket
and gently
rock the lamp back and forth while pushing it into place (see Figure 2). Make sure the lamp is in straight and centered in the reflector hole.
CAUTION:
D
o
NOT allow the reflector to contact the lamp.
4.
Reinstall the reflector and then position the front lens in place matching up the notches on
the lens with the two small tabs on the housing to prevent lens rotation (see Figure 2). Push the tabs on the front rim outward and press the lens into place.
6.2 Fuse Replacement There is a fuse inside the unit which may be accessed by removing the lens and reflector (refer to section 6.1). Under normal operating conditions, the fuse should never blow
. Examples of
abnormal operating conditions would be foreign materials entering the strobe, such as water, ink, etc. If the fuse needs to be replaced, replace only with a fuse of the same type and value:
BB
-
Battery
Powered:
Slow Blow – 2.5A, 5x20 mm fuse (part# 1062-3004-008)
B
A
-
AC
Powered:
Fast Blow - 750mA, 2AG fuse (part# 1062-0201-001)
4
Figure 2 Lamp Replacement
Red Dots
Notches