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Model 415Е
5-23. ETCHED
CONDUCTOR
REPAIR.
А broken or
burned section of conductor can be repaired by bridging
the
damaged
section with a length of tinned
copper
wire.
Allow
adequate
overlap
and
remove
any var-
nish
from
etched
conductor
before
soldering
wire
into place.
5-24.
TRANSISTOR
REPLACEMENT.
a. Do
not apply excessive heat.
See Table 5-3 for
Soldering tool specifications.
b. Use
a heat sink such as pliers or hemostat be-
tween transistor body and hot soldering iron.
c. When installing a replacement transistor, ensure
sufficient lead length to dissipate heat of soldering by
maintaining
about the same length of exposed lead as
used for original transistor.
5-25. DIODE REPLACEMENT.
5-26. Solid state diodes are in many physical forms.
This
sometimes
results in confusion as to which lead
Or connection is for the cathode
(negative) or anode
(positive),
since not all diodes are marked
with the
Standard symbols.
Figure 5-2 shows examples ої some
diode marking methods.
If doubt exists as to polarity,
an ohmmeter
may be used to determine
the proper
connection.
It is necessary to knowthe polarity of the
ohms
lead with
respect
to the common
lead for the
ohmmeter
used.
(For the hp Model 410B Vacuum
Тире
Voltmeter,
the ohms lead is negative with respect to
the common; for the hp Model 412A DC Vacuum Тире
Voltmeter, the ohms leadis positive with respectto the
common.)
Whentheohmmeter indicates the least diode
resistance,
the cathode of the diode is connectedto the
ohmmeter
lead which is negative with respect to the
other lead.
Note:
Replacement instructions are the same
аз those listed for transistor replacement.
5-27.
SWITCH REPAIR OR REPLACEMENT.
5-28.
The
EXPAND
and RANGE
switches are on the
same
assembly,
as are the GAIN and VERNIER
con-
trols.
These
assemblies,
along
with
the
POWER
Switch and the INPUT
switch, may be removed by first
taking off all instrument
covers and using the appli-
cable instructions which follow.
Note:
For
general
soldering
instructions,
refer to Paragraph 5-24 and 5-25.
5-29.
GAIN/VERNIER,
Refer to Figure 5-3 and the
schematic
diagrams
for component identification and
location,
a. Loosen
setscrews
in knobs
and
remove
from
shaft.
b. Loosen
and remove
shaft nut from front panel.
с. Pull
assembly
back
and out of instrument
ге-
moving
lock
washer
and grounding lug from shaft.
Also
remove
white
GAIN/VERNIER
instruction plate
from front panel.
d. Unsolder connecting wires.
Mark each to indicate
which lugs to resolder wires to.
е. Replacement is reverse of removal.
02152-1
Section V
Paragraphs 5-23 to 5-31
5-30. RANGE-DB/EXPAND.
Refer to Figure 5-3 and
the
schematic
diagram
for component
identification
and location.
a. Loosen
setscrews
in knobs
and remove
from
shaft.
b. Loosen
and
remove
shaft nut from front panel.
с. Loosen
the BANDWIDTH
potentiometer to allow
the switch assembly to be pulled free of the front panel.
d. Unsolder connecting wires. Mark each to indicate
which lugs to resolder wires to.
e, Replacement is reverse of removal.
5-31. INPUT.
Refer to Figure 5-3 and the schematic
diagrams
for component
identification
and location.
а. Loosen setscrews in knob and remove fromshaft.
b. Loosen
and
remove
shaft nut from front panel.
c. Pull switch
assembly
free from front panel and
unsolder
connecting
wires.
Mark
each
to indicate
which lugs to resolder wires to.
4. Replacement is reverse of removal.
5-32,
POWER.
Refer to Figure 5-3 andthe schematic
diagrams
for component
identification
and location.
а. Loosen the two nuts holding circuit
board in place
and remove
circuit board from instrument.
b. Loosen setscrews in knob and remove from shaft.
с. Loosen and remove
shaft nut from front panel.
d. Pull switch
assembly
free from front panel and
unsolder
connecting
wires.
Mark
each to indicate
which lugs to resolder wires to.
e. Replacement is reverse of removal.
DIODE
SYMBOL
ANODE -———kk— CATHODE
CONICAL
END
".сатноре
А 1
№дтноре
|
4I5E- A-16
Figure 5-2.
Examples of Diode Marking Methods
5-9
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