Fluke 12 User manual

®
PN 2063508
January2003Rev.1, 9/04
© 2003-2004 Fluke Corporation. All rights reserved. Printed in China.
All product names are trademarks of their respective companies.
12
Multimeter
Users Manual

i
Table of Contents
Title Page
READ FIRST: SAFETY INFORMATION .................................................... 1
SYMBOLS .................................................................................................. 2
DISPLAY .................................................................................................... 3
OPERATING FEATURES .......................................................................... 4
STANDBY MODE ....................................................................................... 5
INPUT RANGES......................................................................................... 5
Autoranging............................................................................................. 6
Manually Selecting a Range.................................................................... 6
MEASURING VOLTAGE ............................................................................ 7
TESTING CONTINUITY AND MEASURING RESISTANCE ...................... 9
TESTING DIODES ..................................................................................... 11
VCHEK AND HOW TO USE IT................................................................... 13
DISABLING iWITH FUNCTION LOCK ............................................. 14
MEASURING CAPACITANCE.................................................................... 15
USING MIN MAX FUNCTIONS .................................................................. 17
Recording Minimum and Maximum Readings......................................... 17

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Users Manual
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Recording Minimum and Maximum Reading with Elapsed Time............. 19
Capturing Continuity Intermittents with Continuity Capture.................. 21
TURNING BEEPER OFF............................................................................ 23
MAINTENANCE.......................................................................................... 23
NReplacing the Battery........................................................................ 23
Replacing the Test Leads........................................................................ 23
Service and Parts.................................................................................... 24
Accessories............................................................................................. 24
SPECIFICATIONS ...................................................................................... 24

1
READ FIRST: SAFETY INFORMATION
This meter has been designed and tested in accordance with IEC Publication 1010. To
ensure that the meter is used safely, follow all safety and operating instructions in this
manual. If the meter is not used as described in this manual, the safety features of the
meter might be impaired.
WWarning
To avoid false readings, which could lead to possible electric shock or personal
injury, replace the battery as soon as the battery indicator (N) appears.
•Do not use the meter if the meter or test leads look damaged, or if you suspect
that the meter is not operating properly.
•Turn off power to the circuit under test before cutting, unsoldering, or breaking the
circuit. Small amounts of current can be dangerous.
•Do not apply more than 600 V rms between a terminal and earth ground.
•Use caution when working above 60 V dc or 30 V ac rms. Such voltages pose a
shock hazard.
•When using the probes, keep your fingers behind the finger guards on the probes.
•Disconnect the live test lead before disconnecting the common test lead.

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Users Manual
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SYMBOLS
The following international electrical symbols are used in this manual:
W Important Safety Information in Manual
∅Not Applicable to Identified Model
BAC
FDC
GDiode
ECapacitor
JGround
TDouble Insulation

12 Multimeter
DISPLAY
3
DISPLAY
Figure 1. Display

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Users Manual
4
OPERATING FEATURES
Figure 2. Operating Features

12 Multimeter
STANDBY MODE
5
STANDBY MODE
In standby mode, the display goes blank to preserve battery life. The meter beeps and
enters Standby if it is ON but inactive for more than 45 minutes. Press any pushbutton
to resume operation. Standby is not allowed if the meter is in the MIN MAX mode.
INPUT RANGES
The input range determines the highest value the meter will measure. Most functions
have more than one range (see SPECIFICATIONS). If the range is too low, the display
shows OL (overload). If the range is too high, the display will show fewer digits of
resolution.

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Users Manual
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Autoranging
The meter defaults to autorange when you turn it on. In autorange, the meter selects
the range automatically.
Manually Selecting a Range
The meter also has a manual range mode. In manual range, you select and lock the
meter in a range. To manually select a range:
1. Press [V]. The meter is locked in the range it is in, and Vis displayed. In manual
range, iis disabled.
2. Press [V] to step through the ranges. NOTE: The 4000 mV range, which can only
be entered in manual range, is convenient when using accessories.
3. To return to autorange, press [V] for 2 seconds (until Vis no longer displayed), or
change the measurement function.

12 Multimeter
MEASURING VOLTAGE
7
MEASURING VOLTAGE
1. Insert the test leads in the jacks.
2. To select a voltage function, put the slide-switch in the middle position. See
Figure 3.
To toggle between dc and ac, press [g].
3. Touch the probes to the test points, and read the display. The meter beeps an
Overload Alert™ when OL (overload) is displayed.
In manual range, you can toggle the meter between a high or low input impedance
mode by moving the slide-switch between the voltage and continuity/ohms positions.
(See “iAND HOW TO USE IT”.) In the continuity/ohms position, the input
impedance of the meter is 2 kΩ, and LoZis displayed to indicate that the meter is in
the low input impedance mode. In the volts position, the input impedance is 5 MΩin ac
and 10 MΩin dc.

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Users Manual
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Figure 3. Measuring Voltage

12 Multimeter
TESTING CONTINUITY AND MEASURING RESISTANCE
9
TESTING CONTINUITY AND MEASURING RESISTANCE
1. Insert the test leads in the jacks, and turn off power to the circuit under test.
External voltage across the components causes invalid readings.
2. Put the slide-switch in the continuity/ohms position (Figure 4).
To toggle between the continuity/diode and ohms functions, press [g].
3. Touch the probes to the test points.
4. In ohms, read the resistance on the display.
In continuity test, the beeper sounds continuously if continuity exists (resistance
< 25 Ω.). Opens and shorts longer than 250 µs are detected. On the Fluke 12,
short-to-open and open-to-short transitions can be captured and visually
displayed. See “Capturing Continuity Intermittents”.
If the meter detects a voltage greater in magnitude than about 4.5 V and the meter is
not in the manual range mode, the meter automatically changes to the voltage
measurement function. (See “CHEK AND HOW TO USE IT”.)

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Figure 4. Continuity and Resistance Measurements

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TESTING DIODES
11
TESTING DIODES
1. Insert the test leads in the jacks.
2. Put the slide-switch in the continuity/ohms position. The meter selects either the
continuity/diode (RG) or ohms (e) function.
If ohms is selected, press [g] to toggle to the continuity/diode function. To toggle
the beeper on or off in continuity/diode test, press [V]. Ris displayed when the
beeper is enabled.
3. Touch probes to the diode (Figure 5A). A forward-voltage drop of about 0.6 V
(typical for a silicon diode) causes the meter to beep once.
4. Reverse probes (Figure 5B). If the diode is good, OL is displayed. If the diode is
shorted (Figure 5C), the beeper sounds continuously in at least one direction.
If the diode is open, OL is displayed in both directions.

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Figure 5. Testing Diodes

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VCHEK AND HOW TO USE IT
13
VCHEK AND HOW TO USE IT
iis a subset of the continuity/ohms function. In i, the meter is designed to
automatically display an ac or dc voltage when the meter detects a voltage greater in
magnitude than about 4.5 V and the meter is not in the manual range mode. THIS
WILL NOT HARM THE METER. iis always enabled (and kis displayed) when
the meter is in the continuity/ohms function unless the meter is in one of the following:
• The manual range mode (i.e., Zis displayed)
• The MIN MAX mode (i.e., jis displayed)
• The capacitance function (i.e., µF is displayed)
WWarning
Repetitive transients on a dc bus will cause ito select ac volts, even
though a hazardous dc voltage may be present. To avoid a misleading display
and possible electric shock, manually select the proper volts function for
measurements on these circuits.
In i, the meter has a low input impedance (~2 ke). When a voltage is displayed,
LoZis also displayed to remind you of this, and the beeper momentarily sounds a
iAlert™. To disable the iAlert in the ohms function, press and hold down
[g] while turning the meter on.

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Use ionly on power supplies and other power sources that have a low output
impedance. Do not use ito measure voltage in electronic circuitry unless a 2 ke
load will not damage the circuit. See † on page 27.
DISABLING iWITH FUNCTION LOCK
To lock the meter in either the continuity/diode or ohms function, and disable i:
1. Put the slide-switch in the continuity/ohms position. The meter selects the
continuity/diode or ohms function. Press [g] to toggle between the
continuity/diode and ohms functions.
2. Press [Z] to put the meter in manual range. Zis displayed. The meter is locked in
the selected function and iis disabled.
In continuity/diode test, press [Z] to toggle the beeper on and off.
In ohms, press [Z] to manually select a range.
To remove the function lock and reenable i, press [Z] for 2 seconds, press [g],
or move the slide-switch.

12 Multimeter
MEASURING CAPACITANCE
15
MEASURING CAPACITANCE
First, turn off power to the circuit, and disconnect and discharge the capacitor.
1. Insert test leads, and move the slide-switch to [E]. (See Figure 6.)
2. Press [E]. The capacitance function is selected and µF is displayed.
3. Touch the probes to the capacitor. When measuring polarized capacitors, be sure
to connect the positive to [&] and the negative to COM. Capacitor dielectric
absorption can cause measurement errors. If more discharge is necessary, the
meter displays “dISC” while the capacitor is discharging.
To exit capacitance, press [E] or [g], or move the slide-switch to another position.

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Figure 6. Measuring Capacitance