– 9 –
9.0 REPLACING THE FLASH
TUBE
1
3
2
4
5
Remove the front bezel screw (
1
)
Firmly grasp the spent flash tube (
4
) and pull it straight out.
Using a lint and oil-free tissue, insert a new flash tube into the socket (
5
).
Slide the front bezel over the new tube and rehinge it at the top. Rotate the bezel back
towards the bottom of the case and reinsert the front bezel screw.
NOTE:
As a safety precaution, the unit will not flash unless the bezel is in place.
Swing the bezel upwards and outward (
2
). Take care not to
break the old flash tube. Ensure that the bezel hooks (
3
) on
the top edge are released. Remove the bezel.
– 12 –
12.0 DETERMINING AN OBJECT’S TRUE RPM
The Pocket-Strobe can be used as a digital tachometer to determine the true RPM
and/or the reciprocation rate of an object. This is done by visually “freezing” the
object’s movement and then reading the LCD display. As with all stroboscopes, it is
important to verify that this frozen image is not a harmonic of the object’s actual rate.
Helpful Hints
■
Knowing the approximate rate of the object in advance gives you a useful
starting point.
■
If the object has a uniform shape, like a multi-blade fan or motor shaft, you must
give it an identifying mark (using paint or reflective tape or equivalent) in order
to differentiate its orientation.
■
A singular image always appears at exactly one half of the object’s true RPM.
■
Mathematical harmonic techniques can be used to determine an object’s true RPM
if it is greater than 12,500 (the upper limit of the Pocket-Strobe).
See Example 3 on page 15.
Example 1 (Within Range):
This example shows why identifying marks are important.
Suppose you want to determine the true RPM of this fan.
The only thing you know is that its speed is less than 3,500 RPM.
If you slowly decrease the flash rate starting from 3,500 FPM,
the following “frozen” images appear:
Image No.:
1
2
3
4
Flash Rate:
3.300
1,650
1,100
916.6
Image No.:
5
6
7
8
Flash Rate:
825
733.3
660
550
WARNING:
Make sure that the flash tube is correctly installed in the
socket. If it is crooked, the light output of the reflector is reduced.
incorrect
