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Maintaining Your P 5
Your P 5 requires no periodic maintenance and has no user serviceable parts inside.
To avoid risk of electric shock do not remove the top cover. To keep it clean use only a soft
cloth moistened with a few drops of clear water or Windex. Never use any solvents or
abrasives. The remote control handset batteries should be removed whenever it will be
unused for an extended period. Remove the battery cover annually to inspect and remove
leaking batteries.
Ground Loops - Eliminating Hum and Buzz
Audible hum and buzzing noises in a system are usually related to issues with the
component grounds. Ground (sometimes called common) is a point of reference for voltages
in virtually all audio and video components. Ground is supposed to remain at zero volts while
the audio signal swings positive (voltage above ground) and negative (voltage below ground).
If ground isn’t at zero, there can be an audible 60 Hz hum (or 50 Hz hum in regions with 50 Hz
AC). The harmonics of these frequencies (120 Hz, 240 Hz, 480 Hz or 100 Hz, 200 Hz, 400 Hz)
may add buzz in addition to the hum.
The ideal of zero voltage ground for all the components in a system is practically
impossible, because some resistance between the ground points of different components is
inevitable. By keeping components close together with their power cords plugged into a
common AC outlet or power strip, you’ll avoid the problems created by resistance in the
house’s wiring.
Hum and buzz is also caused when unwanted voltage flows through multiple
component ground points called ground loops. Here are three tips to avoid ground loops:
1
. Your Cable TV receiver box might require a Cable TV ground isolator. To determine if this
is the case, unplug your incoming cable signal and see if the buzz/hum goes away.
2
. Plug your subwoofer and amplifier(s) into the same outlet as the P 5.
3
. When rack mounting, always use the insulated “shoulder” washers. These break the ground
loops caused by metal-to-metal contact between the rack, the components, and their rack-
mount bolts.
