Wyred 4 Sound MC 7150 - Manual (Page 8)

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7. Verify that the interconnects are working by replacing them with a different set
from a connection that you know works. If these cables were used in the current
setup and the only component that has changed is the MC 7150 continue to the next
step.
8. Now that you have interconnects that you know work, try connecting the
amplifier to another source and speakers that you know function properly.
If you are still experiencing problems and have exhausted your available resources
and time please contact the dealer/distributor that you purchased the product from
for additional support.
Got hum?
Is there too much hum coming out of your speakers? To clarify, if you put
your ear right next to the tweeter of your speaker, it is normal to hear some low
level of hiss. If the hum is easily heard at a distance, try putting your source on mute.
If this eliminates the noise, it’s inherent in the source. If muting your source doesn’t
disconnect the outputs when muted and the hum still exists while muted, try
disconnecting the inputs to the amplifier. If the hum is still there when the inputs are
disconnected, then your amplifier may need service. If the hum is not there when
the inputs are disconnected, try putting a cheater plug (ground isolator) on one
component at a time in order to locate the source of the ground loop. Once the
source is located you can contact the manufacturer for further information
regarding a solution. NOTE: We only recommend using a ground isolator for trouble
shooting purposes, and it should be removed after the problem has been found and
resolved. Having the ground of any unit disconnected can potentially create a
dangerous situation.
An easy way to locate a noisy component is to replicate the problem then
start disconnecting components one at a time, starting with the source end of your
system. Digital cable boxes and satellite receivers are notorious for making ground
loop hum. This is normally caused by the potential difference on the cable or
satellite service input wire (shield side) for either of the boxes when referenced to
ground. If this is the case in your system, the installation of an isolating transformer
would be the easiest solution and they are normally readily available at your local
electronics parts store. A better solution is a power strip with grounded and surge
protected F-connectors that you can pass your cable or satellite signal through.