TM 11-5805-239-35
FG, PP-1209B/FG, and all models of P P -
w h i c h will give a center-scale reading.
1 2 0 9 / F G , proceed as follows:
Note the resistance value.
( 3 ) Reverse the ohmmeter connections to
( 1 ) R e m o v e the plug-in unit to be tested
plug P1 and select the resistance
from the main chassis assembly.
range that will give a center-scale
( 2 ) Use the ohmmeter section of Multi-
reading. Note the resistance value.
meter TS-352/U to check the for-
One value should be at least 1,000
ward-reverse resistance ratio of the
times
the
other.
Replace
a
rectifier
silicon rectifier.
Connect t h e black
that has a resistance ratio much lower
test lead of the TS-352/U to ter-
than 1,000 to 1.
m i n a l 5 of plug P1, and the red test
( 4 ) Repeat the above test procedure for
l e a d to terminal 6 of plug P1, Select
each plug-in unit to be tested.
the resistance range on the TS-352/
W a r n i n g : The failure of selenium
U which will give a center-scale read-
ing. Note the resistance value.
rectifiers can result in the liberation
o f poisonous fumes and deposit o f
( 3 ) R e v e r s e the ohmmeter connections to
p o i s o n o u s selenium compounds. If a
plug P1 and select the resistance
rectifier stack burns or area over, pro-
range that will give a center-scale
vide adequate ventilation immediate-
reading. Note the resistance value.
ly. Avoid inhaling the fumes, and do
One value should be at least 10 times
n o t handle the rectifier until it has
the other, Replace a rectifier that has
cooled.
a resistance ratio lower than 10 to 1,
( 4 ) Repeat the above test procedure for
f. Testing of Silicon Rectifier. To test the
each plug-in unit to be tested.
s i l i c o n rectifiers in Power Supplies PP1209A/
3-4
