6. Tests
Use the following requirements to determine the
acceptability of repaired microphones for return to
stock of reissue.
a. Mechanical Requirements. The mechanical re-
quirements are as follows:
leads must be connected to the microphone terminals.
(b) Electro-Voice Model 600D. One of the
The cord coductors must be connected to the switch.
yellow secondary leads must be connected to the end
terminals and cord connector pins indicator in the
terminal of the terminal board opposite the cord side,
and the other lead must go to the terminal under the
transformer screw. The black primary transformer
(4) Microphone M-29/U. Each microphone must
from the switch terminal grounding to the housing for
all tests.
be provided with a cover, and the windows must meet
heat -sealed to the housing.
b. Electrical Requirements. (1) The following insula-
tion resistance measurements will apply to all micro-
phones included in this Depot Inspection Standard
except Microphone T-50 ((2) end (3) below). The
(3) Insulation resistance for Microphone T-50
insulation resistance between cord conductors, between
(Electro-Voice Model 600D), between the points and
current -carrying parts of switches, between current-
under conditions indicated in the chart below, will be
carrying parts of the plug, and between current-
at least 200,000 ohms. The points above must also
carrying parts of the microphone must be at least
withstand a dielectric test of 100 to 250 volts rms. The
200,000 ohms as measured on Test Set I-142. The
yellow secondary transformer lead connected to the
points above must also withstand a dielectric test of
end terminal of the terminal board opposite the cord
100 to 250 volts root mean square (rms).
must be disconnected for all tests.
(2) The insulation resistance for Microphone
T-50 (Electro-Voice Model 600C), between the points
and under the conditions listed in the chart below must
be at least 200,000 ohms, and the same points must
withstand a dielectric test of 100 to 250 volts rms. The
transformer red leadout wire must be disconnected
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