Model 182C
Theory
4-29. One of the
secondary
outputs
of A1T1 is coupled
to a
full-wave bridge rectifier
consisting of
A1A1
CR5-
CR8, The rectified
voltage is filtered by A1C1,
and
applied
through fuse A1F1 to the
regulator assembly.
Fusing protects the
rectifiers and transformer
if
a
regula-
tor
malfunction results in excessive current flow. The
regulator supplies sufficient current to the
load
to
keep
the output
voltage at a constant
+100 volts. Series re-
gulator A1Q1
controls load current in
order
to
main-
tain the output voltage at +100V.
Variations in
output
voltage due to changes
in load or input line voltage
are
sensed by
differential
comparator
A1A2Q3
and Q4.
If
the output
of the +100V supply changes, the
full amount
of the voltage change Is applied to A1A2Q3by
A1 A2VR2,
and
A1A2Q4
senses only
a
small part of the change in
output voltage. The +100V
adjustment
potentiometer
A1A2R11
sets
the operating point of A1A2Q4. The
output of the differential comparator is coupled to driver
A1A2Q1,
amplified
and used to
control series regulator
A1Q1.
4-30.
A
current limiting function is also part of the +100V
supply operation.
All current furnished
by
the supply
flows through A1A2R4.
The
voltage
drop across this
resistor depends on
the amount of current required. As
the current requirements increase to
the
limit
of
the
supply capability, the voltage
drop
across A1 A2R4
is
used
to set A1A2Q2
into conduction. Since the collector of
this transistor and the output
of differential comparator
A1A2Q2 and Q4 are coupled to
drive
A1A2Q1,
the
amount
of current flowing as well as voltage variations
control the operation of series regulator A1Q1
.
4 31.
Resistors A1A2R2 and
R3
are used in conjunction
with A1A2R4 to
set
up
a condition
for
current foldback
operation. In this type of operating condition,
fully reg-
ulated voltage will be provided to the limit of the supply
capability. When current exceeds capability, the output
voltage will begin to drop
arxl the load will receive less
current. If the output of the supply is
short-circuited, the
output current will be limited to
considerably
less than the
current
available at full loading.
4-32. The -i-IOOV supply
is
protected for turn-on and
turnoff voltage transients Diodes A1A2CR1 artd
A1A2CR2 provide transient protection
for
the
differential
amplifier, A1A2Q3 and A1A2Q4. To prevent the +100V
supply from going negative in the event of an accidental
short circuit (during troubleshooting, for example), diode
A1 A2CR3 provides
reverse
voltage protection.
4-33. A separate supply Is used to obtain voltage
for the
+
100V regulator. This
supply
is used
only within the LVPS
regulator. The ac voltage
from
pins 11
and
12
of
A1T1
is bridge rectified by A1A1CR1-CR4 and
filtered
by
A1A1 Cl.
The supply produces about +10V which is added
to
the
+100V supply to
provide
a
reference source for the
+100V regulator.
Zener
diode A1A2VR1 stabilizes
the
collector voltage for A1
A2Q3.
4-34.
+15-VOLT SUPPLY.
This supply
provides three
voltages.
Approximately
30Vac
p-p
is furnished for
time base line
synchronization;
an unregulated
+27V
is
furnished
for operation
of the HV
oscillator; and
a
regulated +15V is produced for
use in the mainframe
and
plug-ins.
4-35. The secondary voltage developed
by
the power
transformer
at pins 13
end 14 is rectified
by
full-wave
bridge
A1A2CR9-A1 A2CR12 and filtered
by A1C2.
Diode
A1A1CR21 provides reverse voltage protection.
Series regulator
A1Q2
controls the amount of load
current in
order
to
maintain the output voltage at +15V.
Variations
in output voltage are
sensed by differential
comparator A1A2Q7 arxJ
A1A2Q8. A reference
voltage
derived from the
+100V regulated supply
is applied to
A1A2Q7, while
A1A2Q8 samples
any change in output
voltage
due to load changes. The
+15V adjustment
potentiometer
A1A2R20 sets the
operating point of
A1A2Q8. The output of
the
differential
amplifier
is
coupled to driver
A1A2Q5 and used to control the series
regulator.
4-36. Load current flows through
A1A2R13.
The voltage
drop across this
resistor
is used to control the conduction
of A1A2Q6, which has its collector coupled to driver
A1 A2Q5. Thus, both current variations sensed by A1
A2Q6
and voltage changes sensed by the differential amplifier
are coupled
to
the driver A1A2Q5
to
control
series re-
gulator A1Q2. Protection from turn-on or turn-off tran-
sients is provided
by
A1A2CR4. Fuse
A1F2 protects
the +15V
rectifier
and transformer in the event of a
regulator short circuit.
4-37.
-12.6-VOLT SUPPLY. This
supply operates
in a
manner similar
to the +15V supply.
Changes in output
voltage
are sensed
by
differential
comparator
A1A2Q11
and A1A2Q12
and coupled
to driver A1A2Q9
which
controls the
conduction of series
regulator
A1Q3. Current
limiting
action is provided
by
A1A2R22
and A1A2Q10.
Fuse A1F3 protects
against damage
due to regulator
failure and A1A2CR5 is used for
voltage transient
protection.
4 38. -100-VOLT
SUPPLY.
Operation
of the
—100V
supply is similar
to
the +100V supply.
A1A2Q15
and
A1A2Q16
operate
as a differential
comparator,
with
A1A2Q1
6 sensing any change
in
output voltage.
Transistor
A1A2Q14
with A1A2R33
provides
current limiting.
Current foldback
operation reduces
the current
output
in
the
event of
a
short
circuited load. Voltage
and current
variations
are coupled
to driver A1A2Q13
which
controls
the
conduction of series
regulator A1Q4,
Adjustment
of
the supply
output voltage
is
accomplished with
potenti-
ometer A1A2R40.
Voltage transient
protection
is furnish-
ed
by
A1A2CR6,
while A1A2CR7
provides
reverse
voltage protection.
4-39. SUPPLY
CURRENT
AVAILABLE, The
oscil-
loscope power supplies
may be used to furnish
operating
power for vertical
or time base plug ins
designed by the
4-3
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