Bosch Praesideo Service Manual page 26

Praesideo| Service manual | Chapter
Amp Overload
Description:
Extra information:
Fault finding:
Amp Short Circuit
Description:
Extra information:
Fault finding:
EOL failure
Description:
Extra information:
Fault finding:
Pilot Tone Calibration
Description:
Extra information:
Fault finding:
Bosch Security Systems | 2004-28 | 3922 880 62312
Logs the overload of an amplifier in a Power Amplifier
Number of the amplifier which malfunctioned
Check if your cable length over exceeds 1KM and the max load isn't
reached;
LBB4421, 20 Ohm and 250 nF at 100V
LBB4422, 40 Ohm and 125 nF at 100V
LBB4424, 80 Ohm and 62 nF at 100V
LBB4426, 166 Ohm and 30 nF at 100V
(For 70V the load is +/- the half value and the capacitance doubles.
For 50V the load is +/- a quarter of the value and the load times 4.
Please see the Instructions for Use for the correct values)
Lower the volume of the amplifier (To prevent clipping)
Make sure that Power amplifiers have a minimal load of 1/4 of the
used power.
Logs the short circuit of an amplifier in a Power Amplifier
Number of the amplifier which malfunctioned
Check if your cable length over exceeds 1KM and the max load isn't
reached. (See Amplifier overload)
Lower the Call station volume. (To prevent clipping)
Select a 68Hz High Pass filter in audio processing.
Make sure that Power amplifiers have a minimal load of 1/4 of the
used power.
Logs the WLS end-of-line failure in an Amplifier
Number of the amplifier which malfunctioned
Check the loudspeaker lines.
Check if your cable length over exceeds 1KM and the max load isn't
reached. (See Amplifier overload)
Check if a WLS board is connected.
Disconnect the speaker cable at the output of the mentioned
amplifier and connect the WLS board directly at the output. If the
fault resolves the problem must be in the cabling. If it's wouldn't
resolve the WLS board might be broken. (Can be checked by
switching it with one from another amplifier, the fault should move to
that amplifier)
Logs the failure of pilot tone calibration of a Power Amplifier during
start up
Number of the amplifier which malfunctioned
Switch off and on the unit to let the unit recalibrate.
Check at the output of the amplifier, there should be a 7-9V 20khz
pilot tone. You can also measure this at the input of the WLS board.
Check if your cable length over exceeds 1KM and the max load isn't
reached. (See Amplifier overload)
Check first the points as above and if there are other fault events
mentioned in the diagnostic page of this power amplifier. If these are
solved and the units display shows the message "standby" than the
unit needs to be repaired. (see also chapter 9.4.4)
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