MILDTL28803C
4.6.5 Electrical tests.
4.6.5.1 Dielectric withstanding voltage (see 3.5.5.1). Displays shall be tested in accordance with method 301 of
MILSTD202, at atmospheric pressure. The following details and exceptions shall apply:
a.
Test voltage: One thousand volts root-mean-square (rms).
b.
Duration of application: One minute for qualification and group B tests; 5 seconds for other tests.
c.
Points of application: Between all terminals and housing.
4.6.5.2 Life (electrical) (see 3.5.5.2). Displays shall be subjected to 300 hours of continuous operations with the
light source of the highest wattage energized at its maximum voltage. The following test procedures shall apply:
a.
Twelve display units shall be mounted on a vertical aluminum panel, matrixed in three horizontal rows of four
readouts per row.
b.
Tests shall be conducted at the maximum operating temperature specified.
c.
At the completion of the test, the readouts shall be tested in accordance with the dot-to-dot ratio and
4.6.5.3 Overload (see 3.5.5.3). With all segments illuminated, displays shall be subjected to 140 percent of rated
voltage at the power supply for 10 milliseconds minimum. Displays shall then be examined for evidence of damage.
4.6.6 Environmental tests.
4.6.6.1 Moisture resistance (see 3.5.6.1). Displays shall be tested in accordance with method 106 of
MILSTD202. The following details and exceptions shall apply:
a.
Mounting: By normal mounting means on a corrosion-resistant metal panel extending beyond the display
device, positioned 15 degrees from the vertical and uninsulated.
b.
Polarization: During steps 1 to 6 inclusive, a polarizing voltage of 100 volts direct current (dc) shall be
applied between all terminals tied together and the metal panel. Steps 7a and 7b are not applicable.
c.
Load voltage: Not applicable.
d.
Final measurement: Insulation resistance. Within 5 minutes after conclusion of the test and while the
displays are still wet, insulation resistance shall be measured in accordance with method 302 of
MILSTD202, test condition B. Points of measurements shall be between each terminal and housing.
4.6.6.2 Salt spray (corrosion) (see 3.5.6.2). Displays shall be tested in accordance with method 101 of
MILSTD202 with associated mounting and terminal hardware assembled. The following details and exceptions
shall apply:
a.
Test condition B.
b.
Measurements after exposure: Displays shall be examined for evidence of excessive corrosion, warping,
cracking, or other damage.
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