Troubleshooting | or the first component the cable is connected to (i.e. the | |||
cable box, or VCR). If the hum is no longer present, you | ||||
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Use the troubleshooting notes above to solve common | must insert a “75Ω ground loop isolator” before reconnect- | |||
situations that don’t require professional attention. If the | ing the line. You should check with your ADCOM dealer to | |||
steps stated in possible solution do not resolve your prob- | obtain one. If the “75Ω ground loop isolator” works only | |||
lem, then please contact your ADCOM dealer or call the | partially or not at all, then please read note 2 to complete | |||
ADCOM customer service department. Any problems not | the troubleshooting procedure. | |||
covered here should be brought to the attention of your | Note 2: Make sure that the power amplifier is at least 6” | |||
ADCOM dealer or ADCOM customer service department. | ||||
from processor or other equipment using microprocessors. | ||||
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A special note on “hum:” When there is a | Usually putting another component between them is suf- | |||
“hum” audible throughout your speakers, even with the | ficient to minimize the hum. If this does not reduce the | |||
main volume turned all the way down, you have a com- | hum, turn the system off and disconnect all Inputs from | |||
mon phenomenon known as a “ground loop.” A ground loop | the amplifier. If the hum still persists, then your dealer or | |||
is basically a difference in ground voltages between two | service center must examine the unit/system. If the hum | |||
or more components which are connected electrically and | disappears, try another set of RCA cables. Connect one RCA | |||
which creates multiple current paths where there must only | cable at a time to see if one specific cable is responsible. | |||
be one. This difference in potentials creates a 60Hz low- | If any or all cables cause the hum to appear, then the unit | |||
level sound (approximately a low A), that seems to “hum.” | should be evaluated for proper operation by your dealer or | |||
It can be caused by adding new components to your system, | authorized service center. Please see our website or call us | |||
for a list of authorized service centers in your area. | ||||
but that does not imply there is anything electrically wrong | ||||
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with any new component. With the advent of audio/video | Servicing | |||
and home theater systems, the problem has become com- | ||||
monplace. Generally, the cause is the | ADCOM has a technical service department to answer | |||
signal line. This new incoming line may add an additional | ||||
questions pertinent to the installation and operation of your | ||||
ground at a different potential to the AC line ground of | ||||
unit. In the event of difficulty, please contact us for prompt | ||||
your other equipment (refer to note I and 2, to trouble- | ||||
advice. If your problem cannot be resolved through our | ||||
shoot a hum problem). | ||||
combined efforts, we may refer you to an authorized repair | ||||
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Note 1: Cable TV systems can sometimes contribute to | agency, or authorize return of the unit to our factory. To aid | |||
ground loop problems which cause “hum.” To determine | us in directing you to a convenient service center, it would | |||
if your cable system is the contributing factor, disconnect | be helpful if you indicate which major city is accessible to | |||
the | your home. | |||
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14 ADCOM