19
NOTE:
The maximum voltage ratio that can be measured is +50 dB on the 0-250V
range.
e.
If dB measurement is being made to a 0.0006 watt into 500 ohm reference
level, su7 dB from the reading obtained on the 270-5.
4.13 Direct Current Measurement
a.
Do not change the setting of the range or change the function switches while
circuit under measurement is energized.
b.
Never disconnect test leads from circuit under measurement while the circuit
is energized.
c.
Always turn the circuit power off and discharge all the capacitors before
setting the switches or disconnecting the leads.
d.
Never exceed the circuit-to-ground voltage of the instrument (1000V MAX.,
Table 1-1, Item 16).
e.
Always connect the Instrument in series with the ground side of the circuit.
4.14 Direct Current Measurement 0-50
μ
A Range
a.
Set the function switch at + DC.
b.
Plug the black test lead into the - COMMON jack and the red test lead into the
+50
μ
A/250mV jack.
c.
Set the range switch at 50
μ
A (dual position with 50V).
d.
Turn OFF power. Then discharge any capacitors in the circuit.
e.
Open the ground side of the circuit in which the current is being measured.
Connect the VOM in series with the circuit. Connect the red test lead to the
positive side and the black test lead to the negative side.
f.
Turn ON power.
g.
Read the current on the black DC scale. Use the 0-50 figures to read directly
in microamperes.
h.
Turn power OFF and restore circuit to original condition.
NOTE:
For polarity reversing see paragraph 4.2.
4.15 Direct Current Measurement 0-1mA through 0-500mA
Range
a.
Set the function switch at + DC (Figure 4-7).
b.
Plug the black test lead into the - COMMON jack and the red test lead into the
+ jack.
E
G
N
A
R
E
G
A
T
L
O
E
V
G
N
A
R
B
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d
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A
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5
.
2
-
0
0
1
+
o
t
0
2
y
-
lt
c
e
ri
d
d
a
e
R
V
0
1
-
2
0
2
+
o
t
8
g
-
n
i
d
a
e
r
o
t
B
d
2
1
+
d
d
A
V
0
5
-
6
0
3
+
o
t
6
g
+
n
i
d
a
e
r
o
t
B
d
6
2
+
d
d
A
V
0
5
2
-
0
0
5
+
o
t
0
2
g
+
n
i
d
a
e
r
o
t
B
d
0
4
+
d
d
A
!
Summary of Contents for 270-5
Page 1: ...Simpson 270 Series 5 Volt Ohm Milliammeter INSTRUCTION MANUAL ...
Page 4: ...4 NOTES ...
Page 26: ...26 NOTES ...
Page 27: ...27 NOTES ...
