Breaks
in
the
printed
circuit
tracr:..This-is
a
very
rare.faurt.
check
the
rayout
cf
the
circuit
with
a magnifying
glass
.starting
irom-
trre''_'*anu
-_
poirt,
'ot''i"r.,.,"tlitLry
t.uu
dragram)
lf necessary,
repair
it
with
a
s-oldering
Iron
,jritfr
a very
fine
tip.
PARAGRAPH
2)
A)
Faulty
rheostat:
hord
tosether
the.
two
probes
inserted
in
the
s)
x 1
range
turning
the
knob
of
the
rheostat
to
ttri
tett
ant,
*itrr'rr".rrliiiJai
connection,
shortcircuit
points
20
and
22
(see
diasram).
lf
the
needie
io.s
6i.ri
to'i.;;;;pr..;
i[;-;ii.;;l;i"""''
"""'
B)
The
cl.sing
contact
of the
rhe.stat.
circuit.c,rresp,ndirg
t0
the
o
s,cket
d,es
n,t
crose:
proceed
as
above,
turnins
the
??
(scc
rjiaoram\ r+ +h; ,^,1,_r!:o:jrl"!r9q_19
jhq.teft
and
then
snortcirci,it-porniiZf
ant
Bl.c,:g! T
above,
turning
the
rheostat
l'rrO't.-ii,.i-.it-'anu
then
i., _1,.,..."1:T,",*1, ll^,n^i^l,,ll!,
i;-i;-ih;";;,;;.t,'ir,',"
i.".i[
t:;r"i';'i;;'[',,oo3i,li,,l,i,l
ll llit-ltt"
check
the
cros;ng
oi
ih.';;rt.;i;ll
;i;r;";t"';..1;;.il
,'ii"
ffii3l
ii;,..,,,#;;
rs
necessary.
3[JJ:Scli''if.'?ll?".'^1jn',jl':::Lt-*'::,ir-::r::L,I-djls,],
.tF e*
190-0
socket
does
not
Si'".,.1,,;il, lll:,1..j, i:tf,,.f.:-.1.:::t^rl^.,.
^T.d;;;;,t."r,i'n.b.
"6iiirir"o "["#,r:,#
i3i
Shortcircuit points
21
and
25
and-procet.i
rl'i,
riir'cli;h'ii
3L'li'^":HH
ffiTil,i:
+::,'^X:i#':,1'#'il'-'lt6rJo,#*'u
n*
1000
socket
d'es
n,t
P l,X:.rrjro,jl: l]:,,,r",.1:.-'rlll.jl-
th^e^s^rr.unt^
clq.in
_of
-the
ampere
circuit:
The
fautt
is tocated
ill..i:"*1"
,[.,"1fl1:-ji_i..1,111;;
g:g?.4"j,11
l-r,6;'
Rei5ie"t;;,'l;;;,l:i
;iTi.#r]..,?l;E
lll.."li:of"' lf5,:lT :Jtl^hll1q i11;ii9a
iri#
;;
"ih.
''o'i':
ili*jl'',ii,irJ,,l:#,,J,#i:g
rercerv
to
the
end
or
the
scalE
,rn
ii;;p;;;
iJa,ililr"(ro*iv'"r1"'fir'i,*'ili"6,iff
#ix;:
are.
introduced,
this
confirms
the
faurt.
-
si.rtiir.i,li-poiris
19
and
9 to check lhp 0 oAr
:::,"litj.l:.,:_dr
this^_c,onfirms
tf
.
irir:,
sffii,.i,]i"pii,,tr'ii
i',,a'"5
il-';;;.i,T},'.
,6tT;
resistor,
points
1e
and
1 r0r
the.0.sr6
,;;i;i;;';;;
[;iffi
ii;,i'i'rol',,il'"[iro"'L.y.yll
when
the interrupted
varue
is
shortciiiuitu,r
t,ii"i',u[,i['c";es
to the
middre
of the
scare.
PARAGRAFH
3)
A)
Interrupti'n
0f
a resistor
in
the_s-hunt
chain
or
the
Ampere
circuit:
The
fault
is
rccated
in
one
of
the
fottowing
shunts:
57.6
O,
a7b-'O,
'Si6i
O.
An
interrupiion
in
the
57.6
f)
44
,,,,lrr
causes
an interruption
in
Ox1
range and
an
overload
on the
galvanometer
fcr the
r ,r
i,,,
l)
x 10,
Ox
100,
Ox
1000.
An interruption
in the 576O
resistor
causes an
inter-
,,it,tr,,il
in the
ranges
flx
1,
Ox
10 and an
overload on
the
galvanometer
for the
ranges
r,qr
100,
f,)xi000.
An
interruption
in
the 5760O
resistor
causes
the interruption
of the
,,;,r,s
()x
1,
Ox
10,
Ox
100 and a
slight overload
according
to the
position
of the rheostat
r
llr(: range
Ox
1000.
I'A;IAGRAPH 4)
^)
lnterruption
of a
resistor
in series
with the 0hms
ranges: The fault
is in one
of the
r,,lllrv/ing iesisiors,
34.5
O,
382.5
O,
3910
O,
44031
f,),
corresponding
respectively.
t0
the
r.rrr,,r,s
l)x1, Ox10,
Ox100,
Oxi000.
When it has been
declded which
range
is inter-
,
rl,lr:rl,
chec( i[e continuity
of
the
AMP
circuit associated
with it, as
follows:
Alter having
rr',r'rtcd
the comm0n
tr)
socket,
insert
the other end
in the 50s,A socket
for
an interruption
1,r
Ilr0
range
Ox100Q
in the 500pA socket
for
an
interruption
in the
range
Ox10Q
and
rr llrc
5mA
sccket
for an
interruption
in the range
Ox1Q.
These checks should
be
done
, ,
rtriickty
as
possible
to avoid
overl0ading
the circuits
and running
down
the battery.
r)
Interruption 0l the
resistor of
the range
f)x10,000:
This fault
prevents
the
needle
from
rirlrr';rting
when the test
meter
is
used in 50 Hz
A.C. As this may
also
be caused
by a
r,rr
lt in ihe rectifier,
it
is advisable to
measure
the continuity
of the circuit
without
using
tl!) A.C. rnain
supply.
lllr
rcsistors t0
be tested are
200,000O and
259.2
KO. For
this
purpose
it
is necessary
l,r.,hort
circuit
the
pins
of the current
plug
on the
left hand side
of the
analys.er and
one
|rrrl
o{
I
probe
in
thi
tr}
socket
and the other
end
in the
Ox
10,000 socket.
lf..the
resistors
rrr. r:l[icient the instrument
which
was already
at the end
of the scale
on the
Ox
1000
I
ilrr1| m!st
indicate approximately
450,000
tr)
on
the 0hms scale.
lf this
does
not occur
,r
ilr
rrecessary
to chdik
which iesistor
of
the three
making up the circuit
is interrupted.
1)r,; is
done
6y maintaining
the above
menti0ned
conditions
and short
circuiting
the
points
l,r i[]ri 29 and
15
and
28
(see
Ciagram).
The
resistor
t0 be substituted
is that
which,
rttr,r
having been short
circuited,
causes
the needle
to move'
45
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