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Appendix C
Page
7-7/7-8.
Change
A2
Scllematic
Diagram
as
in
Figure C
-
:2
Change A2R61 and 62 to 20
ohms.
Figure C-2.
PIO
A2
Schematic
Diagram.
CHANGE NO.5
Page 44, Replace Paragraphs 4-37
thru
441 with
the
following:
4·37.
REGU LATED POWER SUPPLIES.
4-38. The regulated
power
supplies provide all volt-
ages required by
the
654A circuits. The power sup-
plies
consist
of a (nominally) + 31 volt series regu-
la
ted supply and
a (nominally)
- 26
volt series regula-
ted
supply.
The -
26 volt supply
is
referenced to
the
+31
volt
supp ly.
4-39. The
+31
volt
regulated supply
is of th
e con-
ventional series regulator type. 01 and AIOI are
con
·
nected in the Darlington Configuration to
increase
loop
gain
of
the circuit,
thus
improving
voltage
regulation.
AI
RI4 allows
the
voltage
to
be adjusted
to
+31 volts
(±
0.5); it also affects
the
-
26
volt
supply (making the plus supply
more
positive, makes
the
negative
supply more negative).
440. The - 26 volt regulated supply operates in a
manner similar to
t
he
+31 volt supply. AI05 is a
current
limiter
which conducts
only
when the
load
current exceeds the set value. Conduction
of
Al 05
causes
the
series regulator 02 to reduce
th
e outpu
t
voltage until the load
causin
g
the
excessive current
is
C-2
Model 654A
removed. Diodes AI CR6
and
A
I
CR 7
protect
the
con-
trol transistor
AIQ4 from short circuits between
the
two
supplies
and short
circuits
at
til
e
output of
the
-
26
volt supply.
Delete Figure 4-2 and 4-3
Page
5-13,
Paragraph 545
with the
following:
5-45.
POWER
SUPPLY
VOLTAGE ADJUSTMENTS.
a. Connect a dc voltmeter
to the
power
supply
positive output (AI Pin 12).
b. Adjust
AIRI4 (+30 V Adjust) for 31,
+/-0.2V.
c.
Connect
the
dc voltmeter
to the
power
supply
negative
output
(AI
Pin
13). The voltage
should
be -
26, +/-0.5
V; if
not, change
the
value of AI R15*
to ob
tain the
required voltage
(increasing
the
value
of
AI R15* makes the
power supply voltage less negative, and vice-
versa)
.
d. For power supply troubleshooting, refer
\0
Paragraph 5-78.
Page
5-20, Paragraph 5-77. Replace Steps 9 thru
II with
the
following:
a. If
only
the -
26 V supply is
inoperative
proceed to branch
®.
b. Check
if the
external circuits are loading the
power
supply
by
lifting A
I
Pin 12 and
Al RI8 (Schematic
No
.2).
If
t1le supply
operates
the
trouble
is in the external
circuits.
If tile
supply does
not
operate
proceed to step c of this Paragraph.
c. The
-
26 V supply
is referen
ced
to
the
+31
V.
To
check if the
-
26 V supply is
load-
ing
the +31 V supply first
lift
AI pin 13;
if
the supplies now operate
the trouble
is
in
the
external
circuits;
if the supplies still
do
not operate,
lift
AIRI5*, AIR6
and
AIR7
to
isola
te
the
- 26 V suppJy from tile +31 V
supply.
If
the +31 V supply now operates
the
trouble is in the
- 26
V
does not
ope
rate
troubleshoot
the +31 V
supply.
Check Tl and
th
e
line filter components;
also check A2CRI
thru
AICR4,
AlC9
and
AlCIO.
a.
Troubleshoo
t the -
26 V supply if
you
have arrived here from
branch(!)c.
b. Lift AI Pin
13
to
isolate
the - 26 V
supply
from external circuits. If the
supply now
opera
tes
the trouble is
in
the
external circuits; if
the
-26 V supply does
not operate troubleshoot.
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