MIL-PRF-22710 Switches, Code Indicating Wheel \(Printed Circuit\), Thumbwheel And Push-Button, General Specification ForThis specification covers the general requirements for illuminated and non-illuminated, thumbwheel \(see 6.4.1\), and push-button, printed circuit rotary switches having unsealed and sealed modules and the associated hardware. These switches are designed for low power alternating current \(ac\) and direct current \(dc\) switching applications for use in electronic and communication equipment. Procurement of switches and mounting hardware will require additional data, giving detailed electrical and mechanical requirements, tolerances, and applicable additions and exceptions to the general requirements and tests specified herein \(see 6.2\).

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MIL-PRF-22710H

4.5.11.2 Method II (high impact, for shock type H). Switches shall be tested in accordance with method 207 of

MIL-STD-202. The following details shall apply:

a. Mounting fixtures: As specified in 4.5.11.1a.

b. Electrical load conditions: As specified in 4.5.10d.

c. Monitoring during shock: As specified in 4.5.11.1d. Switch-contact stability shall be monitored for each blow.

d. Measurements after shock: Not applicable.

After the test, switches shall be examined for change in shaft position, and evidence of broken, deformed, displaced,

and loose parts. Failure of lamp shall not constitute failure of the unit.

4.5.12 Insulation resistance (see 3.15). Switches shall be tested in accordance with method 302 of MIL-STD-202.

The following details and exception shall apply:

a. Test-condition letter: A.

b. Points of measurement: Each switch shall be measured separately:

(1) Between all mutually insulated terminals and all mutually connected terminals in a sufficient number of

dial positions to check all possible leakage paths between terminals.

(2) Between all terminals tied together and frame or ground.

c. Application of test voltage: Instantaneous.

4.5.13 Lamp retention (when applicable, see 3.1 and 6.2.2) (see 3.16). Lamp-retention adapters (see figure 1),

simulating the appropriate lamp, shall be inserted into the lamp socket portion of the switch and then withdrawn. This

shall be repeated for a total of five times using both adapters. With the lamp-retention adapter installed in the socket

portion, and with the switch held so that base of the lamp-retention adapter points directly downward, the

lamp-retention adapter shall remain captive to the switch.

4.5.14 Seal (when applicable, see 3.1 and 6.2.2) (see 3.17). Before conducting the test, all gaskets which

normally can be replaced in service without disassembly of the switch proper, shall be disassembled from the switch

and then reassembled with the switch. The switch sections or modules shall be mounted to the test enclosure in

accordance with method I or method II (see 4.5.14.1 and 4.5.14.2), as specified (see 3.1). The seal test enclosure

shall then be subjected to a gradually decreasing pressure at a rate of 10 pounds per square inch per 1 minute until a

negative pressure of 10 lbf/in (gauge) +1 lbf/in (gauge) is reached and then maintained at that pressure for 5

minutes. During this period of minimum pressure, the switches shall be operated for 25 cycles (see 6.4.9) of rotation,

360 clockwise and 360 degrees counterclockwise. A switch with stops shall be operated in both directions to the

limits of the stops; however, the switch shall be operated for an additional number of rotations necessary to equal a

total angular rotation of 25 cycles of 360 degrees in both directions. For unidirectional rotation devices, the cycle

shall consist of 25 cycles of 720 degrees. The pressure shall be increased to ambient barometric pressure at the

same rate as it was decreased while the switch is still in the test enclosure. When the chamber has reached the

ambient barometric pressure, the switches are to be cycled for 25 complete cycles at 360 degrees in both directions.

After removal from the seal test enclosure, the external portion of the printed circuit board shall be wiped dry. The

switch sections or modules shall be so placed that printed circuit boards are in a horizontal position with printed circuit

contacts and brushes on top, when subjected to the dielectric withstanding voltage test (see 4.5.15). The dielectric

withstanding voltage test must be conducted within 30 minutes after removal from the seal test enclosure.

4.5.14.1 Method I (mounting). The switch sections or modules shall be submerged in water to a depth of 6 inches

+2 inches (see figure 2).

4.5.14.2 Method II (mounting). The switch shall be mounted externally on a test enclosure (see figure 2) by its

normal mounting means and the enclosure filled with water so that the switch operating means is in water to a depth

of 6 inches +2 inches.