HP 5245L Service Manual

Section
II
Paragraphs
2-60
to
2-68
c.
WithA5,
connects
output
of first
or
second
deci-
mal counter
(A16
or
A1?)to
trigger-circui.t
of oscilla-
tor
assembly
when
in
SCALER
position.
d. Provides
AC
ground
through
bypass
capacitor
for
signals not
selected
as
input
for
trigger-circuit
of
oscillator
assembly.
2-60.
OUTPUT
SWITCH
ASSEMBLY
A5.
2'61.
The output
switch assembly
(designated
OUT-
PIII
on rear
panel)
includes an
amplifier
stage
and a
nine-position
switch(.1
Hz
thru 10
MHz
and
109
thru
10
in
decade
steps). Circuit
details
are shown
in
the
schematic diagram,
Figure
7-6.
Switch functions
are listed
belor:
a. Provides
standard frequency
signals
at
OUTPUT
connector from
counter
time base if MODE
srvitch
is
not
set ts SCALER
position.
Normally
provides
all
frequencies
from
.lHz
to 10
MHzin
decade
steps
but
frequencies
of
100
Hz
and
belourare interruptedwhen
counter is
reset, and availability
of
frequencies of
1
kHz
and below
depends on
setting of FIINCTION
switch.
b.
^Provides
scaling of
input
signals
byfactor
of 10
to 109
(in
decade
ste-ps) ai
ttte burpur
connector
when
MODE
switch is
set to
SCALER
and
FI]NCTION
switch
is
set to
MANUAL
START.
c. Amplifies
selected output for
aII
selections
(ex-
cept
standard
frequencies
of
1 MHz
and
10
MHz
and
scaler
ratioof
10and 100;
amplifier
isdisabled
by+13
volt
bias
supplied when
these
outputs
are
selected).
2-62.
Po\ilER
SUPPLY:
RECTIFIER
ASSEMBI,YA6;
2-63.
GENERAL.
Several
supplies
are included
in
the
5245L.
Their
characteristics
are
tabulated
in
Table
2-2.
Note
In
the folloring
discussion
complete
refer-
ence designations
are used
to identify
compo-
nents.
This
is
to
prevent
confusion
between
reference
designations
of
power-suppty
com-
ponents
located
onthe
chassis
and components
located
on
the rectifier
assembly
(AG)
and
regulator
assembly
(A?).
For
example,
"R1"
would refer
to a
component
located
on
the
chassis,
while
"A?Rl"would
refer
to a com-
ponent
located
on
the regulator
assembly.
Complete
designations
are
used
when
con-
fusion
might
exist
between
chassis
compo-
nents
and
circuit-board
components.
2-t4
Model
5245L
Table
2-2.
Power
Supplies
Supply
Regulated Remarks
-15
v
+13
v
+20
v
-130
v
+1?0
v
Yes
Yes
Yes
No
No
Series
reg
Series
reg
Series reg
-150
v ref
to
+20
v
+150
v
ref
to
+20
v
2-64.
PRIMARY
POWER.
As
shorpn
in
Figure
7-7
either
115-
or 230-
volt
AC
power
is
connected
through
an
LC
filter
(C5A,
C5B,
L1, L2),
fuse
F1 and front-
panel
po$/er
switch S3B
(part
of SAMPLE
RATE con-
trol) to the
primary
of
pover
transformer T1 and T2.
Moving
slide switch 54
on
the rear
panel
to the
left
exposes
rr115rr
and
connects
the
primaries
in
parallel
for
115-volt operation. Moving
the slide
switch to the
right
exposes
rr230'r
and connects
the
primaries
in
series
for
230-volt
operation. Transformer
T1
sup-
plies power
for
continuous
operation
of the crystal-
oven-heater
control
circuitsl note
that
turning
off
the
counter
does not
turn off
the
po\perto
the
crystal
oven.
Fan
motor
81 is connected
across a
single
primary
winding;
T2 functions
as an autotransformer
to supply
115-volts
to 81
when the
instrument
is
connected for
230-volt
operation.
2-65.
I/IINUS
15-VOLT
SUPPLY.
The regulated
-15
volt
supply consists
of
a
full-wave
rectilier
(AOCRI
through
AOCR4)
whose output
is
smoothed
by
filter
L3-C6,
regulated
by
Q2,
and
further filtered
by
A?C2.
The
A?R4,
A?R5,
A?R6 divider
supplies
a sample
of
the regulated
output
to A7Q2
which amplifies
and
inverts
variations
in
the
sample.
The
A?Q2 output
controls
driver
A?Q1
which
in
turn
controls
regulator
Q2.
Potentiometer
A?R5
permits
adjustment
of the
regulated
output
voltage
by
providing
a
means of
ad-
justing
A?Qz
bias.
2-66.
REGULATOR
OnERATION.
Operation
may
be
traced as follows:
Suppose
the
output
voltage
tends
to
shift torpard
-14
volts.
This
causes
t}re voltage at
the
A?Q2
base
to
go
in
a
positive
direction
resulting
in
a decrease
of conduction and
a
negative
swing
in
A?Q2
collector
voltage; driver
ATQ1 increases
con-
duction
(A?Q1
emitter and
Q2
base
voltage
go
negative);
regulator
Q2
increases
conduction
and returns
the
output
voltage
to
-15
volts.
2-67.
OTHER
REGULATOR
COMPONENTS.
Break-
dorpn
diode
A7CR1
provides
a 6.8-volt
reference
to
the emitter
of
A?Q2. The
A7R1-A7C1 network
pro-
vides
phase
correction for
stability
during
transients.
2-68.
-130
VOLT AND +1?0
VOLT SUPPLIES.
Two
conventional full-wave
rectifiers
supply unregulated
+1?0
volts and
-130
volts. Each rectifier
circuit
pro-
vides
a 150-volt
output
(filtered
by C?
and C8),
but
the circuits
are referenced
to
+20
volts so
tfie
actual
output
voltages
(relative
to
ground)
are
+1?0
volts and
02349-1

HP 5245L Specifications

General

Brand	HP
Model	5245L
Category	Cash Counter
Language	English