Alcad GRF-200 Manual De Instrucciones página 26

The sound produces feedback.
Adjust the feedback control of the audio unit (see step 1 on page
21). If the feedback persists, lower the volume using the volume
controls of the audio unit.
The electric lock doesn’t work.
With the jumper between terminal 10 and
voltage between 12 and 11 in the audio unit is 17 ±10% Vdc, by
making a bridge between terminals 22 and 11. If you cannot find
the fault, there may be something wrong with the electric lock.
In installations with multiple points of entry, calling on one of
the entrance panels does not deactivate the other panels of
the system.
Check connections D3 and D2 between the different panels of the
system. If you cannot find the fault, there may be something wrong
with the audio unit.
In housing compound installations, making a call from one of
the external entrance panels does not disable the entrance
panels of the building which is being called.
Check connections D3 and D2 from the entrance panel to the
identifying accessories of the building. If the fault cannot be found,
there may be something wrong with the audio unit or the identifying
accessory.
The video system does not work in any monitor: auto switch-
on, screen doesn´t come on when receiving a call,..
If this is the case, check the mains voltage in the power supply
unit that feeds the monitors. Check that the voltage of the power
supply between + and – is 17 ± 10% Vdc. Check the connection
between the terminals – from the power supply unit which feeds
the monitors. Check if there's a short circuit and rectify it. Disconnect
the power supplies supply for 1 minute and reconnect it. If the
breakdown continues, disconnect all the + and – terminals from
the power supply unit and check that voltage between + and – is
21 ± 10% Vdc. If it's not correct, there may be something wrong
with the power supply.
Video system does not work in one monitor: auto switch-on,
screen doesn´t come on when receiving a call,..
Check that the ON/OFF switch for the video is in ON position
(on the left). Check that the red led of the monitor is on. Check the
connection between the connection bracket and the monitor. Check
that the voltage between + and – of the connection bracket is 17
± 10% Vdc. If failure cannot be found, there may be something
wrong with the monitor.
Poor image quality on all the monitors: distorted picture, ghost
images, loss of synchronisation.
Check the polarity of the twisted pair.
In multiple access installation, check that you have only one
entrance panel defined as the main one. Make sure that the
D I G I TA L V I D E O D O O R E N T R Y S Y S T E M S
, check that the
Poor image quality on one monitor: distorted picture, ghost
images, loss of synchronisation.
Auto switch-on does not work on any monitor.
Auto switch-on does not work on one monitor.
White picture in all the monitors
White picture in one monitor
multiple-access video line is correctly loaded (resistence of 220
ohms in the unused terminals T2+,T2–). If splitters have been used
in the distribution, check that the voltage between + and – of the
splitters is 17 ±10% Vdc. Check that twisted pair line has a 120
Ohm load: a) if tap-offs have been connected in series the 120
Ohm resistance must be removed from all the intermediate tap-
offs; b) with monitors in series cut the 120 Ohm resistances on all
the connection brackets, but from the one at the end of the line.
Check twisted pair connection in splitters and tap-offs. If you
cannot find the fault, there may be something wrong with the
video unit.
Check the polarity of the twisted pair.
Check that twisted pair line is charged with 120 Ohm: with
monitors in series cut the 120 Ohm resistances on all the connection
brackets, but from the one at the end of the line. Check the position
of the J1 configuration jumper in the connection brackets. If you
cannot find the fault there may be something wrong with the
monitor.
In multiple access installations, check that one entrance panel has
been defined as the main one and check connections D3 and D2
between different entrance panels. If you cannot find the fault
there may be something wrong with the audio unit.
Check that pushing the auto switch-on button the red led flash.
Check that the system is not engaged. If you cannot find the fault,
there may be something wrong with the connection bracket or the
monitor.
Check that the twisted pair to the monitors is connected to the T1+
and T1– terminals of the video unit. In multiple access installation,
check the T2+, T2– connections of the twisted pair between the
different video units. Check the connection between the video and
the audio units. If splitters have been used in the distribution, check
that the voltage between + and – of the splitters is 17 ±10% Vdc.
Check the connections of the twisted pair from the video unit to
the monitors. If failure is not detected, there may be something
wrong with the video unit, any tap-off or any splitter.
Check the connection between the connection bracket and the
monitor. Check the connections of the twisted pair in the monitor's
connection bracket. Check twisted pair's connection from the
connection bracket to the video unit. If failure is not detected there
may be something wrong with the tap-off, connection bracket or
monitor.