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stereo when you were expecting 5.1 surround sound.
• Check if any missing channels have been turned off in
a preamplifier setup menu. For example, the center
amplifier channel will not receive a signal if the
preamplifier has been set to "Phantom".
• If the unit is not on the ON/OFF switch on the 7-
150 might be in the off position.
• An internal fuse on the unit may have blown. Contact
Sherbourn Support for assistance.
The amplifier shuts down often or the line circuit
breaker trips often
• Check that the positive and negative speaker wires are
not shorted together.
• Make sure that no speakers are shorted internally. If
you have an ohm-meter, disconnect the speaker wires
and measure the resistance between the speaker's
positive and negative terminals.
• Measure all speakers and check their impedance spe-
cifications. If necessary, review the "Series and Paral-
lel Connections" section in this manual.
• If you have connected speakers in parallel, the overall
impedance may be too low. It is recommended that
you rearrange the speakers in series to increase the
overall impedance, thus taking some load off the
amplifier.
• Make sure the amplifier has good ventilation and is
not overheating. Allow good airflow underneath
wherever possible. If the amplifier is in a closed rack,
open up the rear panel or use a quiet fan for improved
ventilation.
Poor Bass Performance From Full Range Speak-
ers connected to the 7-150
• Make sure that your preamp does not have the bass
(tone control) level turned down.
• Many surround preamplifiers have controls, which can
direct all the bass to subwoofers, or let your main
speakers play the full range. Make sure that the
preamplifier has been correctly set. If you are not us-
ing a subwoofer, set the speaker options to "Large"
where possible.
• Check that the speaker wires have been connected cor-
rectly: Make sure that the positive of each speaker
connects to a positive output of the amplifier, and the
negative of each speaker connects to the negative
output. If one speaker is wired incorrectly, then it will
be "out of phase" with the others, resulting in poor
bass performance. DOUBLE CHECK ALL THE
SPEAKER CONNECTIONS!!
Turn-on and turn-off thumps
• Plug the amplifier into an unswitched AC outlet, and
use the 3.5mm Trigger Input connection with a trig-
ger between 5-12VDC from the source unit or
preamplifier (such as the Sherbourn PRE-1 Preamp-
lifier/Processor). This should allow the amplifier to
turn on and off silently.
• If your powered subwoofer is the cause of the "thump"
sound (not the other speakers connected to the 7-
150), plug it into a different 115VAC outlet than the
7-150 amplifier so there is no power surge conflict.
• Install a line-conditioning device.
"Hum" Noises in the Speakers
• This problem is more than likely caused by a "ground
loop" in your system, rather than a fault in the 7-150.
Follow these steps to isolate the main cause of the
hum; there may even be more than one. Remember
to turn off all components in your system, including
the amplifier, before disconnecting or connecting any
cables during troubleshooting.
• Remember to turn off all components in your system,
including the amplifier before disconnecting or con-
necting any cables during troubleshooting.
• Try to have all of your equipment on the same electric-
al outlet or circuit. Group all the low power compon-
ents (preamp, CD player, DVD etc.) on a single outlet
or power strip. This is provided that the overall cur-
rent draw from your equipment does not exceed the
rating of the outlet or breaker.
• Disconnect all cables, which come from outside the
room, and check if the hum goes away. This includes
such connections as cable TV, satellite TV, or roof top
antennas.
Make sure that they are disconnected
where they first enter the room, so they are making
no connection to the preamplifier or the TV, or any
other component. If the hum is caused by the cable
TV line, then you will need a "ground loop isolator."
This is an inexpensive device fitted in line with the
coaxial cable feed. Contact your Cable Company or
Sherbourn for assistance.
• Disconnect all connections from the preamplifier to
your TV, VCR or DVD.
• As a test, disconnect any other component, which has
a grounded power cord.
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