If the hum disappears, the fault may be in the input
cables used. Try replacing them with cables that
have better shielding, and make certain that the
input cables are not running on top of any AC power
cords. Change the cables one at a time to determine
if one, or all cables is responsive. If the hum disap-
pears when the input cables are disconnected, but
returns after the cables are changed and the system
re-connected, the problem may be caused by your
.
WARNING:
-
plug the power cord from the AC Power before
replacing the fuse.
Hum may also be caused by faulty earth
grounds in your home’s electrical system. In
the past, cold water pipes were often used for
the earth ground, so it is important to make
sure that your ground connection is still valid
and has not become loose or corroded. The
cold water pipe method may no longer be valid
in some locations due to requirements that the
water meter be isolated from the water mains
with a length of PVC pipe, thus interrupting the
ground circuit. The safest, and most reliable,
approach may be to provide your own ground.
This can be accomplished by having a licensed
-
eted steel grounding rod into the earth, and
using that for your grounding connection
If you have hum in your video display device
(bars that roll up through image at 12-14
second intervals), this may be related to hum
you also experience in your audio system.
The previous suggestion tips may help with
this also. If not, try isolating the ground in the
projectors video signal cable with a base-band
video isolation transformer, such as the Jensen
VB-1BB.
If the hum persists after all of the above
suggestions have been tried, contact the
Optimal Spaeker Design customer service department
for assistance.
MAIN AMPLIFIER FUSE
A FEW WORDS ABOUT HUM AND NOISE
Audible hum, or a discernable low frequency noise,
is one of the most common problems in audio/
video systems. This hum,which may be present
even when the volume is at a low level or when the
“ground loops.” A ground loop occurs when there is
components that are connected electrically. This, in
turn, creates multiple current paths and causes the
low-level noise, or hum.
The growing sophistication of home theater systems,
and the increased number of components used to
create these systems has dramatically increased the
potential for the possibility of ground loops. While
it is natural to suspect that the components in your
system are the cause of the hum, in many cases the
cause may be due to other conditions. In particular,
cable TV connections from outside the house have
become a major source of hum.
In most cases, one of the following suggestions
should help you to solve a hum problem in your sys-
tem. Please try these steps in the sequence shown,
proceeding from one step to the next if the prior
suggestion does not eliminate the problem.
Suggestion #1
Suggestion #3
Suggestion #5
To determine if a cable TV connection is responsible
where it connects to your components. Alternatively,
disconnect the cable TV wire where it is connected at
the wall outlet. Turn your system back on, and listen
if the hum has disappeared. If removing the cable TV
feed has eliminated the hum, you will need to insert a
Ground Loop Isolator before reconnecting the cable
TV feed, or contact your cable TV operator to see if
they can better isolate your cable feed.
Under some conditions, such as a shorted speaker
wire,DC voltage on an input connection or thermal
overload, the XA5180 will place itself in a protect
happens the front panel light will glow red and the
Should this occur, IMMEDIATELY turn the
and disconnect the AC power cord. Examine
all speaker connections to make certain that
there are no shorts. Turn the unit back on. If
the unit continues to go into the protect mode,
contact us for assistance.
The XA5180 uses an external fuse to protect
damage. In the event that a fuse replacement
is required, be certain that a fuse of the original
rating is used. If a fuse continues to fail,
your unit may have developed a fault. In this
event, please contact us for assistance.
b
WARNING:
If you suspect that the
grounding system in your home’s electrical
wiring is causing the hum problem, it is import-
ant that you do not make any changes to the
wiring
yourself. Only a licensed electrician should
make any changes to household wiring, and
they must be made in full compliance with
all local building, safety and electrical codes.
Ground loop problems may also be caused
by poor grounding of the electrical system in
your home, particularly when there are multiple
components with three prong, grounded, pow-
er cords. Try unplugging these components
one at a time, and see if one or all of them is
causing the problem. The ultimate solution to
this type of problem is to re-wire your house
-
ration. We recognize, however, that this may
be impractical and expensive. In some cases,
the use of an approved AC Power Isolation
this problem.
Suggestion #4
PROTECTION MODE
10
Suggestion #2
Ground Loop Diagram
