External - Fluke 93 Service Manual

3
•
18 CIRCUIT
DESCRIPTIONS
3.4.4
EXTERNAL
(BANANA) INPUT/OUTPUT
circuitry
•
Introduction
See
figure 3.10.
The ScopeMeter
Is
provided
with
two Panana
connectors, which are
used as
Inputs
In
the mV,
DIODE, and
OHM
METER
modes
or
as EXTerna
I
trigger
inpirt in
SCOPE
mode. These
connectors
also
serve as outputs
for the
built-in
generator. Protection
circuitry
is
provided
to
prevent
damage
by
overvoltage.
t<27E1a
*0
Text,
mv
Figure
3.10 Schematic diagram
signal flow
fn
EXTemaf
(banana)
input/output
circuitry
•
Detailed circuit
deacription
See
figure
3.1
0 and
circuit
diagram
A2b
(figure 10.6).
mV
DC
measurement
circuitry
The
mV DC
input
voltage on
the red
banana
terminal
is
fed
to
die
L.F.
pan
of
the
channel
A
attenuator
section, via
the followng
path:
R2750, K2750a, K2751
b,
R2761
,
D2751
(refer to circurt
diagram A2b,
figure 10.6).
M/hen
the
ScopeMeter
is
switched
to
mV
DC
measurement
using the
EXT
banana
terminals, the settings
are as
follows:
Table $.4
A-ASIC and
attenuator settings
in
mV DC
mode.
mV DC RANGE
A-ASIC (02301)
LF-ATTENUATOR
(channel A)
300
mV
I
100 mV/div 1-
3
V
100 mV/dIv
O.V