MIL-DTL-62740A(AT)
a. Temperature cycle. Each temperature cycle shall consist of 30 minutes at minus
(-) 60 degrees Fahrenheit (°F) (-51 degrees Celsius (°C)) and 30 minutes at plus
(+) 125°F (52°C). The rate of temperature change between temperature extremes
shall be not less than 5°F (2.8°C) per minute. Power shall be applied to the PWA
for not less than 30 minutes from 20°F (7°C) through the completion of each high-
temperature soak.
b. Random vibration. Following all temperature cycling, the PWA shall be hard
mounted to the vibration table so that the axis of vibration is perpendicular to the
plane of the PWA. The vibration shall be at room ambient temperature, for a
period of 10 minutes, as shown in figure 10.
NOTE: PWAs being procured for simultaneous installation in VTMs being procured do not have
to be subjected to "burn-in" provided the VTMs are subjected to the 16-hour "power
on" burn-in.
5. PACKAGING
5.1 Packaging. For acquisition purposes, the packaging requirements shall be as specified
in the contract or order (see 6.2). When actual packaging of materiel is to be performed by DoD
personnel, these personnel need to contact the responsible packaging activity to ascertain requisite
packaging requirements. Packaging requirements are maintained by the Inventory Control Point's
packaging activity within the Military Department or Defense Agency, or within the Military
Department's System Command. Packaging data retrieval is available from the managing Military
Department's or Defense Agency's automated packaging files, CD-ROM products, or by
contacting the responsible packaging activity.
6. NOTES
(This section contains information of a general or explanatory nature which may be
helpful, but is not mandatory.)
6.1 Intended use. The PWA has 12, 8, and -8 Vdc voltage regulators (U25, U24, U26)
for this and other printed wiring assemblies in the STE/ICE-R VTM. The PWA latches data from
the Data Bus (P1-21 through P1-28) into U16, U17, U18, or U19 and U20 depending on the I/O
control line used. Latched data is used to select or deselect the circuits to perform the following
functions: A Constant Current Source (U15, U21, U22, U23) can source either 1.0 or 0.1 mA.
A Digital-to-Analog Converter (DACON; U11, U12) provides -3.75 to 3.75 Vdc according to a
10-bit binary input. A four input digital Multiplexor (U3) can be controlled to route signals
through a Divide by n+1 Counter (U9), which can selectively divide the input frequency by any
number from 1 to 64. A Test Push Button Debouncer (U6, U7) provides a clean signal for the
microprocessor interrupt signal and an event flag. The output of the Multiplexor or the Divide by
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