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|  MIL-T-82570A(OS)
4.4.5.3 Breech mechanism air loss test. With the breech mechanisms removed,
gradually charge each (using the test equipment of 4.4.4.3, 4.4.4.4, and
4.4.4.5) at a rate not exceeding 250 psig per minute to a pressure of 2000
psig pneumatic and permit them to cool for a period of 2 hours. The breech
mechanisms shall then be bled to a pressure of 1600 plus or minus 10 psig.
After a 24-hour period, observe the pressure reading, using the gage of
4.4.4.5. The pressure loss in each breech mechanism shall not exceed 5 per-
cent Compensation may be made for change in pressure due to temperature.
4.4.5.4 Bore size of barrel test. The "GO" bore gage (4.4.4,6) shall pass
through each barrel with an axial force not to exceed l5O pounds.
4.4.5.5 Dielectric strength tests. For the purpose of this test the barrel
and training gear heater switches shall be placed in the ON position and the
barrel heater thermoswitches shall be cooled with C02 to close the contacts.
Temporarily connect the training gear, and, on the Mod 7 only, the junction
box on Barrel Number 2 to terminal 14 of TB 102 (in the junction box on Barrel
Number 3). The tube assembly shall withstand a potential of 1000 volts, 60 HZ
ac (4.4.4.7) applied between terminal 14 of TB102 and all input terminals as
shown on the external wiring diagram, NAVSEA Dwg 694740 (Mod 5) or 694741
(Mod 7), for one minute without evidence of breakdown. The input terminals
may be connected together for this test.
4.4.5.6 Insulation resistance test. For the purpose of this test the tube
assembly shall be in the same condition as required for the dielectric strength
test (4.4.5.5) with the exception that the training gear heater switch shall
be in the OFF position. Immediately after the hipot test, the insulation
resistance between the hipotted points shall be 3 megohms minimum at 500 vdc
and the insulation resistance between terminals 1 and 2 of TB102 and terminal
14 of TB102 shall be 0.5 megohm minimum at 500 vdc.
4.4.5.7 Ground circuit continuity. Continuity shall exist between terminal
14 of TB102, pin G of test receptacle J2 (in the junction box on Barrel Num-
ber 3), and any portion of the junction box aS well as anY of the three con-
trol boxes and overheat sensor assemblies. On the Mod 5 only continuity
shall also be indicated between terminal 14 of TB102 and any portion of the
junction box on Barrel Number 2.
4.4.5.8 Training gear heater resistance test. Before the tests below are
conducted, the thermoswitch shall be jumpered and the training gear heater
shall be energized with 115 volts, 60 Hz ac applied at terminals 1 and 2 of
TB103 in the junction box for a period of one hour.
4.4.5.8.1 With the training gear heater switch in the OFF position, the
resistance between pins 1 and 2 of TB102 in the junction box shall be 6.9 ohms
plus 0.7 ohms or minus 0.4 ohm.
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