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Page Title:
Test Method 4. Las Printed Wiring Board Assembly Functional Test |
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| MIL-S-52860D
APPENDIX
TEST METHOD 4
LAS PRINTED WIRING BOARD ASSEMBLY FUNCTIONAL TEST
1.
TEST APPARATUS:
a.
DC power supply - constant output or adjustable to provide a voltage of
20 0.3 Vdc at currents up to 40 mA, load regulation <0.5%, ripple < 100
mv p-p, total voltage change due to ambient temperature change and drift
with time during the test period <0.5 Vdc.
b.
DC Voltmeter - between 19 and 21 V, minimum resolution 0.1 Vdc, minimum
accuracy 1.5%.
c.
DC Ammeter - Between 10 and 30 mA, minimum resolution 0.1 mA, minimum
accuracy 2%, maximum full scale voltage drop (burden voltage) 0.3 V.
d.
Ohmmeter - resolution 1% of reading, accuracy 2% of reading.
e.
LED, drawing D13220E3816 (contained in TA13220E3800).
NOTE:
Number of required meters may be minimized by use of suitable switching
arrangements or by moving test leads as necessary.
2.
TEST PROCEDURE:
NOTE:
During first article tests all voltage, current, and resistance values
required shall be recorded. During production tests, check marks may
be used to denote compliance when the values fall within specified
limits.
a.
Connect the LED (item 1e) with its anode to terminal "VDD" and cathode
to terminal 6.
Set power supply for 20.0 0.3 Vdc and connect positive lead through dc
b.
ammeter to terminal "+20"; connect negative power supply lead to
terminal 3. The LED shall not be lit.
c.
Observe and record current. It shall be between 10 and 30 mA. After
completing measurement, remove ammeter if desired, connecting +20 V
lead directly to terminal "+20".
Measure voltage at terminal "VDD". It shall be 12.0 1.0 Vdc.
d.
e.
Connect ohmmeter across terminals 2 and 4.
f.
Momentarily connect jumper between terminal "VDD" and terminal 5. The
LED shall illuminate and remain on. The ohmmeter shall read more than
100K ohms. Record value.
g.
Momentarily connect jumper between terminal 1. The LED shall turn off
and remain off after removing jumper. The ohmmeter shall read less tan
500 ohms. Record value.
h.
Disconnect ohmmeter test leads and turn off power supply.
i.
Connect positive lead of the power supply to terminal 3 and the
negative lead to terminal "+20" and turn on power supply.
j.
Momentarily connect jumper between terminal "VDD" and terminal 5. The
LED shall not illuminate.
k.
Turn off power supply, reverse power supply leads into terminals "+20"
and 3, then turn on power supply.
l.
Repeat steps e, f, and g to verify no damage has occurred.
NOTE:
Steps i, j, and k need to be performed only during the initial
functional test after burn-in (i.e. may be omitted during burn-in and
during and after environmental tests).
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