28
(MT12 - Gb2004)
At the door station a whistle is heard
(Larsen effect)
The electric door-speaker (amplifier) is badly
housed in the push-button panel; the micro-
phone has to be stuck to plate. Lower the
volume.
Radio reception on the door station
The defect can occur when there is a transmit-
ter working in the proximity. Apply a condenser
from 0.1µF between terminals 1 and 3 of the
electric door speaker (amplifier).
INTERCOMMUNICATING SYSTEMS
No sound in either channel. Intercommu-
nicating phone not working
Short-circuit between + and - of the power
supply. Faulty power supply.
Calls from the door station activate. No
sounds in either channel. Intercommuni-
cating phone is working
No power supply between 3 (+) and 4 (-) of the
electric door-speaker (8Vdc). Faulty power
supply.
No sounds from the intercoms to the door
station
The connection between 1 of the intercoms and
G of the power supply has been interrupted.
The connection between D of the power supply
and 1 of the electric door-speaker (amplifier)
has been interrupted. Faulty electric door-
speaker (amplifier). Faulty power supply.
No sounds from the door station to the
intercoms
The connection between 2 of the intercoms and
2 of the power supply has been interrupted. The
connection between C+ of the power supply
and 2 of the electric door-speaker (amplifier)
has been interrupted. Faulty electric door-
speaker (amplifier). Faulty power supply.
The intercommunicating calls activate, but
the door station is still on
Check that cable 7 is connected to 7 of the
power supply and not to terminal
. Faulty
power supply.
- Check for the presence of the mains voltage
in the terminals 230Vac (or 127Vac) of the
power supply.
- The power supply is not provided with fuses,
but it is protected against overloading or short-
circuiting by a heat sensor (thermoprotector),
to restore power, it is necessary to cut off the
mains voltage for about one minute. Reconnect
power after having repaired the fault.
- Check the voltage output of the power supply
(see in detail the values indicated in the power
supply chapter).
Nothing at all is working
Absence of main voltage. Short-circuit or over-
load of the terminals of the power supply output.
Faulty power supply.
The lock does not work
Faulty lock. The cross section of the cables
indicated in bold type is insufficient. A connect-
ing cable to the lock has been interrupted.
Faulty power supply.
Calls from the door station do not activate
The common connection of the push-buttons
on the push-button panel has been interrupted.
A call to an individual intercom does not
activate
The connecting wire from the door station to the
intercom has been interrupted. The intercom
buzzer is faulty or badly set. In intercoms with
electronic call check that the handset is hung up
correctly.
No sound from either channel
Absence of power between 3 (+) and 4 ( - ) of
the electric door-speaker (6÷8Vdc). Short-cir-
cuit between + and - of the power supply. Faulty
power supply.
No sound from the intercoms to door sta-
tion
Connection 1 from the intercoms to the electric
door-speaker has been interrupted or short-
circuited. There is no ground connection to
terminal 4 of the electric door-speaker (ampli-
fier). Faulty electric door-speaker (amplifier).
No sound from the door station to the
intercoms
Connection 2 from the intercoms to the electric
door-speaker (amplifier) has been interrupted
or short-circuited. Faulty electric door-speaker
(amplifier).
Audio with humming in the background
(50/60Hz)
The wires have been canalized together with
the cables that power AC loads. Wrong con-
nections or under dimensioned cross-section
of wires (see recommendation and table on
page 26). Faulty power supply.
TROUBLESHOOTING
PRELIMINARY CHECKS
FAULT AND PROBABLE DAMAGE
- Check that the cross section of the cables
corresponds to what is indicated on page 26
and in the descriptions of each individual dia-
gram.
I
NTERCOMS
*
V
IDEOINTERCOMS
*
T
ELECOMMUNICA
TION
The intercommunicating calls do not acti-
vate
Check that cable 7 is connected to 7 of the
power supply. Faulty power supply.
No sound in the intercommunicating ser-
vice
Faulty power supply.
SYSTEM WITH MORE ENTRANCES
Entrance A is never activated
Short-circuit between 5 and 6 of the exchanger.
Faulty exchanger.
Entrance B is never activated
Short-circuit between 3 and 4 of the exchanger.
Faulty exchanger. No power supply to 1 and 2
of the exchanger (13Vac).
