ASV 3270, User Manual

Page: 9 / 12

9
Mode 5 - Speaker Test
In speaker test mode, the ASV 3270 produced a tone with
pulsed DC current at 200mA to enable testing of speakers.
CAUTION: Do not probe random wires while in this mode.
The ASV 3270 outputs 200mA of current at up to 9V, which
may damage some of the sensitive circuits in a modern
vehicle.
The most common use for this mode is in determining which
wires at a head unit run to
which speakers.
Simply connect the ASV 3270
to a pair of speaker wires while
in speaker test mode and a
tone will be heard from the
speaker.
Approximately every 2
seconds, the tone will change
as a DC pulse is introduced.
Use this pulse to check the
polarity of the speaker by
feeling for movement of the speaker cone. If the red wire is
connected to the positive speaker wire, the cone will move
outwards during the pulse, otherwise it will move inwards.
Speaker test mode is also very handy to check that no speaker
wires are shorted to ground: Connect the black lead to ground
and the red lead to one of the speaker wires. If either A or B (or
both) LEDs light up, or the tone is heard from the speaker, a
short circuit to ground is present.
NOTE: A false reading may be given if the speaker wires are
connected to the output of a head unit or amplifier.
The LEDs will also give an indication of the impedance of the
speaker under test, but because this is done by measuring the
DC resistance, it may not always be completely accurate.