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Sencore TF151 - Disassembly Instructions; TF151 Calibration; Leakage Calibration Procedure; Gm Calibration Procedure

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DISASSEMBLY INSTRUCTIONS
To
remove
the
TF151
from
its
case
for
recalibration
of
the
leakage
or
Gm
scales
of
the
meter
or
any
repa
irs
that
may
be
necessary,
it
is
a
simple
matter
to
remove
the
four
screws
holding
the
chassis
in
the
case
as
follows:
1.
Remove
the
two
screws
on the
bottom
of
the
panel
holding the
panel
to
the
case.
2.
Remove
the
two
screws
at
the top
of
the book
holder
on
the
rear
of
the
case.
3.
Lift
the
from
panel
away
from
the
case.
This
.
will
expose
the
Leakage
and Gm
calibration
co
ntrols
on the top
of
the
chassis.
To
reassemble
the
TF151,
simp
ly
reverse
the above,procedure.
CALIBRATION
OF
THE
TFlSl
Calibration
of
the
TFlSl
is
extremly
simp
le and
easy.
There
are
only two
cal-
ibration
contro
ls
inside
of the
TFlSl,
the l
eakage
calibration
and the
Gm
signal
calibration.
Both
are
on
the top
of
the
chassis
and
are
accessable
when the
TFlSl
is
removed
from
its
case.
Leakage
Calibration:
1. Set the TYPE
switch
to the
NPN
or
'N'
channel
position
and
the
function
switch
to
the
LEAKAGE
position
on the
regular
transistor
side
of the
sw
it
ch.
2.
Connect
the
positive
lead
of
a 1
milliamp
meter
to
the C
or
collector
jack
of
the
TF151
and
the
negative
lead
to
one
side
of
a
2K
pot.
3.
Connect
the
other
side
of the
2K
pot to the B
jack
of
the
TFlSl.
Adjust
the
2K
pot
for
a
reading
of 1
milliamps
on
th
e
externa
l
meter.
4.
The
TFlSl
meter
should
now
read
1
milliamp.
If
it
does
not,
adjust
the LEAKAGE
CAL
control
on
the top
of
the
chassis
until
the
TFlSl
meter
reads
1
milliamps.
See
figure
10
for
lo
cation
of
control.
Gm
Calibration:
. 1.
Connect
an
oscilloscope
such
as
th
e
Sencore
PS148
ground
lead
to the S
or
source
jack
of
the
TFlSl
and the
vertical
input
to the
Gl
or
gate
j
ack
.
2.
Set the
function
switch
to the GATE 1
section
on Gm
Xl
and
depress
the GAIN
button.
The
signal
should
be a
square
wave and
be
0.34
volts
peak
to
peak.
If
the
~ignal
is not O. 34
volts
peak
to
peak,
adjust
the Gm
CAL
conrrot.~'~"of
the 1
FlSl
chassis
until
the
sig
nal
output
is
0
.34
volts
peak
to
peak.
THe
tGlT\'~.
0
range
signal
is
take
. n
from
the Xl
range
through
a
preCision
resisr~
and
n
..
. s
n~
adj
us
tment.
_ J ! ..
(~I~.s
/.
J
:.
,.'
~""'.i;w",t.~JIo'Ic
i~.
Fig
u
re
10.
Location
Of
Leakage
And G
m
Cal
Controls
In
The
TFlSl
CIRCUIT
DESCRIPTION
REAR
OF
TF
151
CHASSIS
The
Se
ncor
e
TFlSl
is
a unique
breakthrough
in
solid
state
servicing
equipme
lit
,;
.
It
incorporates
a
regular
transistor
tester
and
a
field
effect
transistor
tester
in
b\~e
piece
of
equipment.
The
regular
transistor
section
is
Llsed
to
measure
the AC
beta
of
~
transistor.
1l1is
is
accomplished
by
applying
a 60
Hertz
signa
l
simultaneously
between
the
collector
and
the
emitter
and
between
the
base
and the e
mitter.
The
ratio
of
average
co
L!
eqor
currem
to average
base
current
as
the
transistor
conducts
on
each
half
CYcl"~a.
20

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