HP 5245L - PRINTED CIRCUIT COMPONENT REPLACEMENT; ADJUSTMENTS; Regulator Assembly A7

Section
VI
Paragraphs 6-11
to 6-18
6.I
I.
INSTRUMENT
COYER
REIIOYAL.
6-t2.
To
remove
top or
bottom
cover, unlock
two
quarter
turn fasteners
which
secure
cover to instru-
ment.
Then
slide cover
toward
rear
of instrument.
To
replace
cover,
reverse
procedure.
WARNING
Lt5/230
VAC
AND
DC
SUPPLY
WrRES ARE
EXPOSED
WHEN
EITHER
INSTRUMENT
COVER IS
REMOVED.
EXERCISE
CAUTION
DURING
TROUBLESHOOTING,
ADJ
UST.
MENT,
OR
RE P AIR.
REMOVE
POWER
FROM
INSTRUMENT
BEFORE
REMOVING
OR REPLACING
COVERS
OR A,SSEMBLIES.
6-t3.
ASSEmBLY IOCATION
6-14. Top
and
bottom
internal
views of
the
Counter
are
shown in
Figures
6-4
and
G-5.
These
figures
show
the
location
of the
assemblies,
connectors,
chassis
parts
and
test
points.
Table 6-3.
Assembly
Designations
A1
INPUT
SWITCH
ASSEMBLY
(SENSITTVIT9
A2
TIME
BASE
SWITCH ASSEMBLY
A3
FUNCTION
SWITCH ASSEMBLY
A4 MODE
SWITCH
ASSEMBLY
A5
OUTPUT
SWITCH
ASSEMBLY
A6
RECTIFIER
ASSEMBLY
A?
REGULATOR
ASSEMBLY
A8
DECIMAL
POINT
ASSEMBLY
A9 MEASUREMENT
UNITS ASSEMBLY
A10-
A14
LOW
FREQUENCY
DECIMAL
COUNTER
A15-
A.16
MEDIUM
FREQUENCY
DECIMAL
COIJNTER
A17
HIGH FREQUENCY
DECIMAL
COUNTER
A1B
HIGH FREQUENCY
READOUT
A19-
A20
INPUT
AMPLIFIER
ASSEMBLIES
A2t
FIJNCTION
CONTROL
ASSEMBLY
l^22
GATE
CONTROL
ASSEMBLY
A23
SAMPLING
CONTROL
ASSEMBLY
A24
CRYSTAL
OVEN ASSEMBLY
425 OVEN
CONTROL
ASSEMBLY
A26
OSCILLATOR
ASSEMBLY
M,7 MULTIPLIER
ASSEMBLY
A28
MEDIUM
FREQUENCY
DECADE
DTVIDER
A29,
A34
LOW
FREQUENCY
DECADE
DTVIDERS
A35
TIME
BASE
CONTROL
ASSEMBLY
Model
5245L
6-15.
PRINTED
CIRCUIT
COffTPONENT
REPLACEfiIENT.
6-16.
Component lead
holes in
the
Model
5245L cir-
cuit
boards have
plated
walls
to ensure
good
electri-
cal contact
between
conductors
on the
opposite
sides
of the board.
To
prevent
damage to this
plating
and
to
the replacement
component, apply
heat
sparingly
and
work carefully.
The following
replacement
pro-
cedure
is recommended.
a. Remove
defective
component.
b.
Melt
solder in
component
lead holes.
Use
clean
dry
soldering iron
to
remove
excess
solder.
Clean
holes
with
toothpick
or
wooden
splinter.
Do
not use
metal
tool
for
cleaning as
this
may
damage through-
hole
plating.
c. Bend lead
of replacement
component
to the
cor-
rect
shape and
insert component leads
into
component
Iead
holes.
Using heat
and
solder sparingly,
solder
leads
in
place.
Heat may
be applied
to either side of
board.
A heat
sink
(longnose
pliers,
commercial
heat-sink
tweezers,
etc)
should be used when
replac-
ingtransistors
anddiodes
in order
to
preventconduc-
tion
of
excessive heat from
the
soldering iron
to
the
component.
d. Through-hole
plating
breaks are indicated
bythe
separation from
the board of the round
conductor
pad
on
either
side
of
the
board. To repair
breaks,
press
conductor
pads
against
board and
solder replacement
component
lead
to conductor
pad
on
both sides of the
board.
6.17.
ADJUSTffIENTS.
6.18.
REGULATOR ASSEMBLY
A?.
CAUTION
When
troubleshooting
or adjusting
the
power
supply, do not
short supplies
to
ground
or
to
each other. This
will
damage the diodes and
transistors.
a.
Set linevoltage
to normalvalue
(115
or
230Vac).
b. Connect
dc voltmeter
(Table
6-2)
to buss
wire
between A16(11)
and A18(6).
c. Voltmeter
should read +20
Vdc
+
0. 5 Vdc.
If
voltage
is
outside
this range, adjust
ATRl7
(figure
7
-7.
d. Vary line
voltage from
103
to
t27
Yac
(20?
to
255
Vac). The +20
Vdc
supply
should not vary
more
than
0. 5 Vdc.
e.
Check
aII
supplyvoltages at locations,
and under
conditions
shown in Table
6-4.
Note
Input
sensitivity levels must
be rechecked
if
power
supply voltages are
readjusted.
6-2
02349-1