Amplifier Ground Short Circuit Test; General; Test Instructions - Bosch Praesideo Service Manual

Praesideo| Service manual | Chapter

11 Amplifier ground short circuit test

11.1

General:

There has been a possibility that the Shortcut to ground circuit could brake down in the Praesideo boosters which
are or have been connected to the 48V DC back up power supply. The Shortcut to ground circuit could brake
down due to a too high voltage while connecting the 48V DC back up power supply.
A simple test can be made to check the Shortcut to ground circuit of the amplifier;
At the back of the amplifier you have to make a temporary short circuit between the 100v output and the
mechanical ground. In the diagnostic page this error message will appear: Amplifier ground short: Channel x.
After an accept and reset this message should be gone. If this message or other amplifiers ground short
messages stays in the diagnostic list, please contact the service department of Bosch Security systems in Breda.
When the Praesideo units are build in a rack, the units as well as the rack should be connected
to ground. When Battery back up is used, the negative pole must be connected to mechanical
ground. Advisable is to make a connection from the 48V minus pole at the back of the
Praesideo to the mechanical ground of the rack.
11.2

Test instructions.

When using a 48V DC battery backup power device (charger), make sure during the check it's
mechanically not connected to the 48V DC minus. If this is impossible than always connect first
the minus pole connection, before the positive pole connection.
1. Disconnect your Praesideo booster from the mains supply.
2. Connect a current measurement device between the back-up battery and the back-up battery input
contacts. First the minus wire than the positive
3. If you measure a current higher than 100uA than your Praesideo booster Shortcut to ground circuit is
defect.
Bosch Security Systems | 2004-28 | 3922 880 62312
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100uA is OK
Current measure device
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