Daktronics AB-1600-1.5,2.5 - Manual (Page 50)

4-8 Maintenance & Troubleshooting
Lamps
There are 64 lamps per lens/reflector assembly (or 32 lamps per
lampbank). Each lamp rests in a socket on the lampbank. As
illustrated in Figure 48, when the lampbank is mounted on the back
of the lens/reflector assembly the lamps extend into the reflector
shells of the assembly.
The life rating of a lamp is defined as the average number of hours
within which 50 percent of a test quantity is expected not to fail and
within 70 percent of that rated life, 90 percent are expected not to
fail. The 7.5-watt lamps used in the 1600 series, 2.5-inch display have
a rated lamp life of 12,004 hours when operated at 21.48 volts.
Typically, lamp failures for the 12,004-hour, 21.48-volt lamp may be
expected as follows.
• Three percent of the lamps normally fail upon reaching 35
percent of the rated life. Thirty-five percent of 12,004 hours is
4,201 hours.
• Ten percent of the lamps normally fail upon reaching 70 percent of the rated life. Seventy
percent of 12,004 hours is 8,402 hours.
• Fifty percent of the lamps normally fail upon reaching 100 percent of the rated life. The
remainder of the lamps lasted longer than the rated lamp life of 12,004 hours.
The table below presents this information in another way. It shows the predicted lamp failure rates
for various sizes of small matrix displays based on a lamp voltage of 21.48 volts and assuming the
display is operated 18 hours per day. The figures are based on the manufacturer’s test data and
laboratory conditions.
Predicted Number of Lamp Failures
For Various Display Sizes
Failure
Percentage
Hours of
Operation
Days in
Service
8x48
384
Lamps
8x64
512
Lamps
8x80
640
Lamps
8x96
768
Lamps
8x112
896
Lamps
16x112
1792
Lamps
3 4,201 233 12 16 20 24 27 54
10 8,402 466 38 51 64 76 89 179
50 12,004 666 192 256 320 384 448 896
§
Lamp life predictions are for lamps operating in a laboratory with continuous operation in a
stable temperature and mechanical environment. Actual values will differ from predicted life
because of switched operation, varying temperature, mechanical vibrations due to wind, traffic
and sign service and actual hours of operation. Data is that of the manufacturer.
Lamps in this display are accessed either by removing the lampbank to which the lamps are
attached or by removing the lens in front to the lamp. If just a few lamps here and there need
replacing it is easier to remove the lenses in front of them. If there are many lamps that need
replacing on a single lampbank (five or more) it is easier to remove the lampbank from the lens
assembly. Both methods of lamp removal/lamp replacement are addressed in this sub-section.
Complete the following steps to access and service lamps by removing a lampbank.
1. In order to access the lampbank, pull the lens/reflector assembly from the display. Refer to
Lens/Reflector Assemblies in Section 4.3 for instructions on removing this assembly.
Figure 48: Lampbank and
Lens/Reflector Assy.