Amprobe PM55A User manual

PM55A
Automatic Precision Pocket Meter
Users Manual
•Mode d’emploi
•Bedienungshandbuch
•Manuale d’Uso
•Manual de uso
PN 2728864
July 2006
© 2006 AmprobeTest Tools.
All rights reserved. Printed in Taiwan
English

SELECT
4
1
2
3
Press for 2 seconds
to turn meter on.
PM55A
ALCD display
BRotary switch to select functions
CSELECT-button to select alternate functions and turn the power off and on.
DPermanently attached red test lead for positive (+) polarity and black test lead for ground
reference (-)

1
PM55A Pocket Meter
Contents
Introduction........................................................................................................2
Safety Information..............................................................................................2
Symbols Used in this Manual ..........................................................................3
Turning the Meter On and Off .............................................................................3
Making Measurements .......................................................................................4
AutoTectMode ..............................................................................................4
Continuity, Audible With Symbolic Display......................................................5
Electric Field EF-Detection, VolTect..............................................................5
Voltage.............................................................................................................7
Resistance .......................................................................................................7
Frequency ........................................................................................................7
Capacitance .....................................................................................................7
V dc, V ac, and Line-Level Hz...........................................................................7
Diode ...............................................................................................................7
600 Ω..............................................................................................................8
µA dc and µA ac ..............................................................................................8
Product Maintenance..........................................................................................8
Maintenance ....................................................................................................8
Cleaning...........................................................................................................8
Troubleshooting...............................................................................................8
Battery Replacement........................................................................................8
Repair .................................................................................................................9
Specifications ...................................................................................................11

2
Introduction
This unique meter has a full complement of features in a package only 3/8 inch thick, weighing less
than 3 oz. for the utmost in shirt-pocket portability. The PM55A is fully autoranging and has an
oversized, easy-to-read digital display. With an AutoTect™ feature that enables the meter to detect
and display measurements of AC Volts, DC Volts and Resistance. The PM55A offers VolTect™, a
built-in non-contact voltage detection of AC voltage. Although very small, this meter is fully UL safety
rated to CAT III levels and is UL listed. The AmprobePM55A precision meter includes
measurement extras such as capacitance, frequency, DC microamps and safety extras such as
transient protection to 4 kV and overload protection to 600 V.
Safety Information
•The PM55A Digital Multimeter is certified for cULus and EN61010-1:2001; CAT II 600 V, CAT III
300 V, class 2 and
pollution deg. 2.
•This instrument is EN61010-1 certified for Installation Category II
(600 V). It may only be used to make measurements on energy limited circuits within equipment
and not directly connected to mains.
•This instrument is EN61010-1 certified for Installation Category III
(300 V). It is recommended for use with local level power distribution, appliances, portable
equipment, etc., where only smaller transient overvoltages may occur, and not for primary supply
lines, overhead lines and cable systems.
•Do not exceed the maximum overload limits per function (see specifications) nor the limits
marked on the instrument itself. Never apply more than 600 V between the test lead and earth
ground.
•Inspect the DMM, test leads and accessories before every use. Do not use any damaged part.
•Never ground yourself when taking measurements. Do not touch exposed circuit elements or test
probe tips.
•Do not operate the instrument in an explosive atmosphere.

3
•Exercise extreme caution when: measuring voltage >20 V // current >10 mA // AC power line with
inductive loads // AC power line during electrical storms // current, when the fuse blows in a
circuit with open circuit voltage > 600 V // servicing CRT equipment.
•Remove test leads from circuit before opening the case.
•Always measure current in series with the load – NEVER ACROSS a voltage source.
Symbols Used in this Manual
N Battery WRefer to the manual
TDouble insulated XDangerous Voltage
FDirect Current JEarth Ground
BAlternating Current RAudible tone
PComplies with EU directives >
Underwriter Laboratories, Inc.
Turning the Meter On and Off
•Press the SELECT button for approximately 2 seconds to turn the meter on.
•To turn the meter off, press the SELECT button until the display goes blank.

4
Making Measurements
All measurements described in this manual use the Red test lead for positive (+) polarity and Black
test lead for Ground reference (-) unless otherwise specified
AutoTectmode is the default function in Auto V-Ωposition. Press the SELECT button momentarily
to select and step through the functions:
•AutoTect
•Continuity
•EF
•ACV
•DCV
•Ω
•Hz
•Cx
•AutoTect

5
AutoTectMode
This AutoTectfeature automatically selects measurement function of
V dc, V ac, or resistance based on the input via the test leads.
●With no input, the meter displays Auto when it is ready.
●With no voltage signal but a resistance below 6 MΩis present, the meter displays the resistance
value.
●When a signal above the threshold of 1.2 V dc or 1.5 V ac up to the rated 600 V is present, the
meter displays the appropriate voltage value in dc or ac, whichever larger in peak magnitude. The
Happears indicating ac V. The default of no icon is dc V.
●The AutoTecttest mode input impedance is lower than most digital multimeters and LoZ is
displayed on the LCD. Switch to the manually selected V dc or V ac, if the circuit being tested is
sensitive to the meter input impedance. Input impedance is approximately 900 Ω, helping
determine if voltage is from leakage (so-called “ghost” voltages) or a hard connection. “Ghost”
voltages will be zeroed out by the low input impedance.
●Overload-Alert Feature
When more than 600 V is present, the meter displays OL with a warning beep tone. Disconnect
the test leads from the signal immediately to avoid hazards.
•Range-Lock Feature
When a measurement reading is displayed in the AutoTectmode, press the SELECT button
momentarily to lock the function-range. The LCD annunciator Auto turns off. Range-lock can
speed up repetitive measurements. Press the SELECT button momentarily again to return to
AutoTectmode.
•When making resistance measurements in AutoTectmode, an unexpected display of voltage
readings alerts you that the circuit under test is still energized.
Continuity, Audible With Symbolic Display
With Auto on the LCD, press the SELECT button once to select Continuity function. The meter will
show a symbolic open-switch display when it is ready. A continuous beep tone and a symbolic
closed-switch indicates a closed circuit. Continuity is used for checking wiring connections and
operation of switches.
Electric Field EF-Detection, VolTect
With Auto displayed on the LCD, press the SELECT button momentarily 2 times to select the EF-
Detection feature. The meter displays EF when it is ready. Signal strength is indicated as a series of
bargraph segments on the display and variable beep tones. See the VolTectspecifications later in
this manual for a complete description of the bar graph indicators.
•An antenna is located at the top left corner of the meter, which detects electric field surrounding
current-carrying conductors. It is ideal for tracing live wiring connections, locating wiring
breakage and to distinguish between live or earth connections.

6
•For more precise indication of live wires, such as distinguishing between live and ground
sockets, use or V ac manual function selection for direct contact voltage measurements.
Note
For Maximum sensitivity, hold the meter away from the VolTect  corner.
SELECT SELECT
PM55A

7
Voltage
With Auto on the LCD, press the SELECT button 3 times to select V ac function. The meter displays
LoZBVwhen it is ready.This function is auto-ranging.
With Auto on the LCD, press the SELECT button 4 times to select V dc. The meter displays LoZ V
when it is ready. This function is auto-ranging.
Resistance
With Auto on the LCD, press the SELECT button 5 times to select resistance function, The meter
displays MΩwhen it is ready. This function is auto-ranging.
Frequency
With Auto on the LCD, press the SELECT button 6 times to select frequency function, The meter
displays Hz when it is ready. This function is auto-ranging.
Capacitance
With Auto on the LCD, press the SELECT button 7 times to select capacitance function, The meter
displays nF when it is ready. This function is auto-ranging.
Return to Auto
Press the SELECT button 8 times to return to AutoTecttest mode.
V dc, V ac, and Line-Level Hz
Turn the rotary switch to the V position to select common impedance
Hi-Z voltage measurements. V dc is the default function. Press SELECT button momentarily to select
V ac. The AC annunciator Bappears. Press momentarily again to select the Line-Level Hz function.
Line-Level Hz input sensitivity varies automatically with V ac range selected when Line-Level Hz is
selected. Measuring the signal in V ac function WHILE selecting Line-Level Hz function in that V ac
range automatically sets the most appropriate sensitivity for higher voltage applications. This can
avoid electrical noises as in 110/220 V line voltage applications. For example, If the reading shows
zero due to insufficient signal levels, select Line-Level Hz function BEFORE making measurements (at
6 V ac range) will set the highest sensitivity.
Diode
Turn the rotary selector to the GR /600 Ωposition. Diode test is the default function. The reading
shows the approximate voltage drop across the test leads. Normal forward voltage drop (forward
biased) for a good silicon diode is between 0.400 V to 0.900 V. A reading higher than that indicates a
leaky diode (defective). A zero reading indicates a shorted diode (defective), and the meter will give a
long beep as continuity warning. OL indicates an open diode (defective). Reverse the test leads
connections (reverse biased) across the diode. The digital display shows OL if the diode is good. Any
other readings indicate the diode is resistive or shorted (defective).

8
600 Ω
Press the SELECT button to select the lowest 600 Ωrange for lower resistance measurements. It is
an extended range to complement the AutoTectresistance function.
µA dc and µA ac
Turn the rotary switch to the µAposition, µA dc is the default function. There is no annunciator for
dc. Press the SELECT button momentarily to select µA ac. The ac annunciator Bappears.
Product Maintenance
Maintenance
Do not attempt to repair this meter. It contains no user serviceable parts. Repair or servicing should
only be performed by qualified personnel.
Cleaning
Periodically wipe the case with a damp cloth and mild detergent; do not use abrasives or solvents. If
the meter is not to be used for periods of longer than 60 days, remove the battery and store it
separately
Troubleshooting
If the instrument fails to operate, check battery, leads, and replace battery as necessary. Double-
check operating procedure as described earlier in this manual.
If the display locks up, press the SELECT button for approximately 6 seconds to reset the
microprocessor.
If the instrument voltage-resistance input is subjected to high voltage transient (mostly caused by
lightning or switching surge to your system) by accident or abnormal conditions of operation, the
series fusible resistors will react (become high impedance) like fuses to protect the user and the
instrument. Most measuring functions through this input will then be open circuit. The series fusible
resistors and the spark gaps should then be replaced by qualified technician. Refer to the LIMITED
WARRANTY section for obtaining warranty or repairing service.
Battery Replacement
If the meter starts up with persistent resetting display or with low battery icon Nturns on, replace
the battery. The meter uses one 3 V coin battery IEC-CR2032.