33
M
AINTENANCE
& T
ROUBLESHOOTING
A
DVANCED
T
ROUBLESHOOTING
If the picture regularly breaks up, then the signal received may be too weak or too strong to
allow the digital TV receiver to generate a stable picture.
Have your service provider confi rm that the signal level at the machine is 72 dBuV + / - 25 dB.
This is equivalent to +12 dBmV, and includes the range of -13 dBmV to +37dBmV. These levels are
acceptable for both analog and digital TV signals.
If signal levels are not OK, you are unlikely to have good reception unless signal strength can be
improved - antenna relo- cation or changes to your amplifi ers (masthead or distribution) may be
indicated.
Remember amplifi ers should only be used by your installer to provide the minimum necessary boost
to signal strength.
Interference from impulse noise may be causing pictures to break up and audio to drop out
momentarily.
Check for domestic sources of impulse noise (i.e. the use of light switches, fridges, hair dryers, air
conditioner, etc.).
If present, arrange for all cables, connectors, outlets and splitters between the antenna and the
receiver to be upgraded in accordance with antenna installation guidelines. Recommends the use of
quad shielded coaxial cable and F connec-tors.
A masthead amplifi er may have boosted the signal outside the receiver’s “operating window”,
making reception impossible.
The masthead amplifi er (appears as a small box on the antenna pole within about a meter of the
antenna arms) may be able to be turned down - if your antenna is on your roof you should arrange
for an antenna installer to perform this task.
When digital broadcasting services begin operating in an area some masthead amplifi ers (boosters)
operating at maxi-mum output or maximum gain may need to be turned down to avoid signal over-
load for digital receivers. This matter should be determined by an antenna installer, who will be able
to adjust the amplifi er for you.
Please note that performing this operation may affect any existing analog signals, so you
MAY
need
to fi nd a medium point between adequate analog reception and good digital reception.
