Troubleshooting - Bose Entero 440 Guia Del Instalador

15.Troubleshooting

Problem
No sound, no power
(Usually an indication of a
power supply problem, either
in the power line itself or the
amplifier's power supply.)
(Usually signal-source, bad
cable or partial output short
circuit related.)
Power on, low output
or no output
(Usually signal-source, bad
cable or partial output short
circuit related.)
Playback mixed with hum
Distortion
(Usually caused by excessive
loss in the input controls when
the mixer/ equalizer/crossover
does not produce enough
output. Also caused by over-
driving that results in output
clipping, or current limiting
caused by excessively low load
impedances.)
Care
Unnatural sound
(Some parts of the frequency
band do not sound balanced
with the rest of the band.)
If you are having trouble or suspect a problem with the Bose
try some simple troubleshooting before contacting an authorised Bose Service Center.
What to do
• Amplifier power off. Turn on.
• Power cord is disconnected.
• Poor fit between the plug and AC receptacle. Try another receptacle.
• Power off at AC receptacle. Check with tester or lamp.
• Blown amplifier fuse. Replace fuse.
• Open thermal breaker. Allow amplifier to cool and the breaker
will reset itself.
• Input level controls set too low. Check and reset at source, pre-amp or
gain control 13 (see section 5)
• Check to see if problem is at the source. Move the input connections
to another amplifier you know is working.
• Be sure that there are no small strands of wire touching similar strands
coming from the other wire in the cable.
• Make sure the speakers are functioning correctly.
• If you are using bridged-mono mode, make sure the Mode Switch
is set correctly.
• Use a voltmeter to determine if the power line voltage is dropping
excessively when the amplifier is driven hard.
• Check or replace the connecting cables.
• Make sure that each screw terminal connection is tight.
• Signal cables may have been routed too closely to AC cables,
power transformers, motors or other EMI inducing device.
• Connect another source to the power amplifier inputs.
If the hum stops, the problem lies with the original source component.
• Input level controls set too high. Check and reset.
• Check speaker connections and verify that all screw connections
are tight and that there are no stray strands of wire to cause
short circuits.
• Verify that the total load impedance presented to the amplifier is within
the limits described in this manual for the mode of operation selected.
• Wipe the front panel and chassis with a soft, dry cloth.
• For stubborn spots, use a mild dish soap or detergent sparingly
applied to a soft cloth.
• Don't use alcohol, ammonia, or other strong solvents.
• Check the EQ cards. Verify that the EQ card corresponds to the model
speaker being used and that the EQ card is installed in the proper
channel. Verify that the speakers are connected to the same channel that
the corresponding EQ card is installed in.
15. Troubleshooting
Entero
Multi-Channel Amplifier,
® ®
17