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| ADCOM GTP-880 Owner’s Manual48
49ADCOM GTP-880 Owner’s Manual |
Resolving Problems
Use the chart on the opposite page to solve common situ-
ations that don’t require professional attention. If the
steps stated in possible solution do not resolve your prob-
lem, then please contact your ADCOM dealer or call the
ADCOM customer service department. Any problems not
covered here should be brought to the attention of your
ADCOM dealer or ADCOM customer service dept.
A special note on “hum:” When there is a low-volume
“hum” audible throughout your speakers, even with the
main volume turned all the way down, you have a com-
mon phenomenon known as a “ground loop.” A ground loop
is basically a difference in ground voltages between two
or more components which are connected electrically and
which creates multiple current paths where there must only
be one. This difference in potentials creates a 60Hz low-
level sound (approximately a low A), that seems to “hum.”
It can be caused by adding new components to your sys-
tem, but that does not imply there is anything electri-
cally wrong with any new component. With the advent
of audio/video and home theater systems, the problem
has become commonplace. Generally, the cause is the
Cable-TV incoming signal line. This new incoming line may
add an additional ground at a different potential to the
AC line ground of your other equipment (refer to note I
and 2, to troubleshoot a hum problem).
Note 1: Cable TV systems can sometimes contribute to
ground loop problems which cause “hum.” To determine
if your cable system is the contributing factor, discon-
nect the Cable-TV incoming signal line (round, 75Ω) at
the wall, or the first component the cable is connected to
(i.e. the cable box, or VCR). If the hum is no longer pres-
ent, you must insert a “75Ω ground loop isolator” before
reconnecting the line. You should check with your ADCOM
dealer to obtain one. If the “75Ω ground loop isolator”
works only partially or not at all, then please read note 2
to complete the troubleshooting procedure.
Note 2: Make sure that the power amplifier is at least
6” from the GTP-880. Usually putting another compo-
nent between them is sufficient to minimize the hum. If
this does not reduce the hum, turn the system off and
disconnect all Inputs from the amplifier. If the hum still
persists, then your dealer or service center must examine
the amplifier. If the hum disappears, try another set of
RCA cables. Connect one RCA cable at a time to see if one
specific cable is responsible. If any or all cables cause the
hum to appear, then the preamp or processor should be
evaluated for proper operation by your dealer or autho-
rized service center.
System Reset
In rare cases the GTP-880 internal processor may freeze or
lock-up causing abnormal operation. This is common to all
micro-processor controlled devices when the unit is subject
to excessive static discharge, AC line noise, or power spikes.
In most cases it is easy to solve this problem by simply
unplugging the GTP-880 from its AC power source for
about five minutes. After waiting, reconnect the power
cord and turn the unit on. If the unit functions normally,
no further action is needed.
In the event that the unit still does not operate prop-
erly, it may be necessary to manually reset the proces-
sor. Note, however, that when the processor is reset you
will lose all settings including digital audio assignments,
surround mode settings, speaker configurations, tuner
presets and any other memory items. For this reason we
strongly recommend that you record these settings so that
it is easy to restore them after resetting the processor.
To reset the unit to factory default settings you will need
to enter the discret remote control command. Please
refer back to the discrete remote control commands
table. The command name is “Factory Defaults”, the IR
code is 86h. This should reset the system.
If the manual reset does not solve the problem, contact
your authorized ADCOM dealer, an authorized ADCOM
service center or contact ADCOM’s service department
directly for further advice.