TM 11-5805-239-35
CHAPTER 2
FUNCTIONING OF POWER SUPPLY PP-1209(*)/FG
w a v e rectifier in which current flows only dur-
2-1. General
ing the positive half-cycles of ac input (A
Power Supply PP-1209(*)/FG is a rectify-
of fig. 2-1). During these half-cy
ing unit that converts 105115-volt, 60-cycle-
c l e s , the electron current flows from the gro-
per-second (cps), single-phase alternating cur-
unded side of the ac input line, through the
rent (ac) to pulsating direct current. It con-
grounded load to output terminal board TB1,
sists of a main chassis assembly and eight
output current control resistor R3, dc output
plug-in units. Each plug-in unit contains a
fuse F1, output current-limiting resistor R1,
half-wave rectifier circuit that receives its ac
rectifier CR1, input current-limiting resistor
input from a common ac input circuit in the
R2, terminal 7 of jack J2, and input fuse F2, to
main chassis assembly, and provides a separ-
t h e live side of the input ac line. Output cur-
ate (either positive or negative) dc output.
rent control rheostat R3 is an adjustable re-
E a c h dc output is individually adjustable from
s i s t a n c e that controls the value of the output
0 to 100 milliamperes (ma) at voltages that
dc available at terminal board TB1. Blown-
vary from approximately 155 volts at 0 milli-
fuse indicator DS1 is connected in parallel
a m p e r e to approximately 129 volts at 100 mil-
with dc output fuse Fl, and lights when F1
liamperes. The polarity of the dc output of
i s b l o w n o r m i s s i n g- f r o m
the
circuit.
Cap-
each individual plug-in unit is determined by
acitor Cl filters the dc output. Bleeder resis-
the position in which it is plugged into the
tor R4 (used in PP1209B/FG modified in
main chassis assembly.
accordance
with
MWO
11-5805-239-35/1,
and PP1209C/FG) dissipates the charge on
2-2. Circuit Analysis
C1 when the plug-in unit is removed from
t h e main chassis assembly. Resistor R4 is con-
The
PP-1209(*)/FG
is
connected
to
a
105-
n e c t e d between terminals 3 and 4 of plug P1.
to 125-volt ac supply by polarized plug P3
b. N e g a t i v e D c 0 u t p u t . W h e n p l u g - i n u n i t
and the, ac input cable. The live side of the
plug P1 is connected to jack J1 of the main
ac input is applied through ac input fuse F2
chassis assembly (with the word NEGATIVE
to terminal 7 of each jack J1 and J2 of the
a t the top), the circuit is arranged as a half
main
chassis
assembly.
(Terminals
7
of
all
wave
rectifier
in
which
current
flows
only
jacks J1 and J2 are connected in parallel. )
during the negative half-cycles of the ac in-
The polarity of the dc output of each plug-in
put.
During
these
half-cycles,
the
electron
unit depends on whether its plug connector
c u r r e n t flows from the live side of the ac in-
P1 is connected to jack J1 or jack J2. When
put line, to input fuse F2, input current-
plug connector P1 is connected to jack J2,
l i m i t i n g resistor R2, rectifier CR1, output cur-
the dc output is positive. When plug connec-
r e n t - l i m i t i n g resistor R1, output fuse Fl, out
tor P1 is connected to jack J1, the dc output
put,
current
control
rheostat
R3,
terminal
is negative. Plug P2 of each plug-in unit is a
board TB1, and to the load which completes
dummy.
(unwired)
plug.
The
functioning
of
t h e path to the grounded side of the input ac
one of the eight c i r c u i t s o f t h e p o w e r s u p p l y
line.
is: described in a a n d b b e l o w .
The
other
Notes
1. Power supplies having order No. 10437-PP-61-
seven circuits consist of identical parts, and
C2C2 have all circuits reverse-wired with respect to
f u n c t i o n in the same manner.
all other order numbers (fig. 32).
DC O u t p u t . W h e n p l u g - i n u n i t
a. P o s i t i v e
2. Power Supplies PP-1209B/FG that have been
plug P1 is connected to jack J2 of the main
modifid by MWO 11-580523935/1, and PP-1209C/
chassis
assembly
(with
the
word
POSITIVE
FG have bleeder resistor R4 connected across capaci-
at
the
top),
the
circuit
is
arranged
as
a
half-
tor C1.
2-1
