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TROUBLESHOOTING GUIDE
13
A 21 will not turn off when
audio signal is removed
PROBABLE CAUSE
Power cord is disconnected
REMEDY
Hum and / or buzz
through speakers
Ground loop between preamplifier
and A 21 or at the equipment rack
Move the Ground switch to its Lift position
Install nylon shoulder washers on both sides of
the panels of all equipment to insulate metal
from touching the rack
Check polarity of DC source with a voltmeter
Try connecting a 9 V battery to the 12V DC input
Make sure Auto Turn On selector switch
is in its Audio position
Auto Turn On selector switch in
wrong position
Auto Turn On selector switch in
wrong position
Connect each speaker to the opposite channel
on the A 21. If the same speaker remains distorted,
the speaker or its wire is damaged. If the other
speaker distorts, the problem may be with the
A 21, the preamp, or a source component
Move the Ground switch to its Lift position.
Install cable isolation device such as the
Xantech 634 Ground Breaker
www.xantech.com
Ground loop from cable TV
Contact Parasound Technical Service
Other ground loop
Problem with preamplifier or source
component
Switch the left and right input cables. If
distortion moves to the other channel, the
problem is with a component other than the A 21
Load impedance at speaker terminals
is too low
Make sure the A 21 has adequate ventilation
Move switch to its Stereo position
Mono Bridge switch is in the Mono
bridged position
Damaged speaker
Move to the correct position for the
jack in use
Balanced-Unbalanced Input switch
is in the incorrect position
Not enough ventilation
Make sure Auto Turn On selector switch
is in its 12V position
A 21 is overheating
No power
TROUBLE
Distorted sound
A 21 has overheated - red Hi Temp
indicator is on
Allow A 21 to cool. Check that there is adequate
ventilation around the A 21. Be sure the load
impedance of each channel is no less than 4 Ω
Check speaker load impedance. Check speaker
wires and connections
Check input connections or try a
different set of cables
Over-current protection circuitry has
been activated- one or both blue
channel LEDs not illuminated
Bad connection from preamplifier or
controller
Sensitivity level too high
Turn level controls clockwise
Turn Sensitivity knob clockwise toward 200 mV
AC Voltage selector switch is in the
wrong position
Auto Turn On selector switch is in
wrong position
Make sure the switch is in the
correct position for your region
Level controls turned too low
DC trigger source wired in reverse
or voltage too low
AC fuse blown
Replace with same value fuse
Turn the Audio trigger Sensitivity
knob counterclockwise
Sensitivity incorrectly adjusted
Check for correct position of the Auto Turn On
switch
Connect power cord
Make sure the speaker or speaker
selector load is 4 ohms or higher
Power on, but no sound
On-Off button glows red
and channel indicator(s) off
Auto turn on doesn’t
function with a
trigger voltage
Auto turn on doesn’t
function with an audio
input signal