Chapter 1
Overview
17
The Overload Indicator
The Overload indicator is located on the left side of the front panel of
the Bridge Amp and to the right of the Status indicator on the Quad
and Octal Bridge Amps.
The Overload indicator is normally off. If the indicator lights when a
transducer is attached, it indicates an out-of-compliance condition
(meaning that the excitation voltage drops because too much current
is being drawn by the load). When the Bridge Amp detects a problem
with the transducer (for instance a wiring fault with a transducer
causing a short-circuit), the overload indicator will glow yellow or
amber and will remain on until the fault is rectified.
If the overload indicator remains on with a transducer attached, the
transducer should be removed immediately to minimize the risk of
damage to the transducer. Check the transducer wiring carefully
before re-attaching the transducer. If the fault persists, refer to the
Troubleshooting section of this Owner’s Guide.
For the overload indicator to function, power must be applied to the
Bridge Amp via a PowerLab. LabChart software does not need to be
loaded.
When a software application is running and a channel is being zeroed,
the Status indicators for the other channels should temporarily be off.
The Back Panel
The back panel of the Bridge Amp provides all the sockets required to
connect the Bridge Amp to the PowerLab and to other front-ends.
I
2
C Input and Output Sockets
Two nine-pin sockets are used to communicate with the PowerLab
(they are marked ‘I
2
C Bus’: a ‘bus’ is simply information-transmission
circuitry such as cables and connectors). These sockets allow multiple
front-ends to be used independently with one PowerLab. Power and
control signals to the front-ends come from the PowerLab. Many
front-ends can be connected to the system, in series, output to input,
providing there is the same number of channel inputs available on the
PowerLab (this is discussed in more detail in the next chapter).
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