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CAP5 - Five way protection system
Cambridge Audio has developed a proprietary protection system to ensure
reliability and a long life for its amplifiers and the speakers they are connected
to. This protection system comprises of five main protection methods:
1. DC detection
Indication -
Unit has switched off during operation. The Direct, Speaker A/B
and Mute light flashes together in the following sequence, one flash with long
pause between flashes. Read below for more information.
Description -
CAP5 offers loudspeaker protection if the output of the amplifier
goes to a high constant voltage (DC) because of some internal fault. This is a
rare fault although detecting it could just save those expensive loudspeakers.
Remedy -
Due to the necessary sensitivity of the DC protection circuit,
extremely hard clipping of the amplifier may cause DC protection to be
triggered. If this fault occurs, please contact your dealer for service.
2. Over temperature detection
Indication -
Unit has switched off during operation. The Direct, Speaker A/B
and Mute light flashes together in the following sequence, two quick flashes
with long pause between flashes. Read below for more information.
Description -
Over temperature is caused by a combination of high listening
levels and low impedance speakers. CAP5 includes temperature detection
which constantly monitors the heat generated by the output transistors. If the
monitored temperature reaches a high level (suitably within the limits of the
output devices) the amplifier will automatically switch into a fault mode. The
unit should ideally be left for 15 minutes in this state to cool down adequately.
If the unit has not fully cooled down then the temperature may reach the limit
soon after the amplifier is powered up. If the loudspeaker impedance is low
the temperature of the amplifier may rise faster as the amplifier is working
harder. If the amplifier is mounted in a cabinet or the ventilation slots are
obstructed the over temperature detection may activate/reactivate after a
short listening time.
Remedy -
The internal temperature of the output transistors has reached the
over temperature limit. Leave the unit for 15 minutes to cool down before
pressing the Standby button to resume normal operation.
3. Overvoltage/overcurrent detection
Indication -
Unit has switched off during operation. The Direct, Speaker A/B
and Mute light flashes together in the following sequence, three quick flashes
with long pause between flashes. Read below for more information.
Description -
CAP5 offers V/I (voltage/current) protection by constantly
monitoring the output transistors to keep them working inside their Safe
Operating Area (SOA). The SOA is a set of limits given by the output transistor
manufacturer to ensure reliability. The V/I protection has been incorporated
within the amplifier circuitry to provide a fast response to temporary overload
conditions. When the V/I protection is triggered the unit will continue to
operate but distortion may be heard as the unit protects the output transistors.
Remedy -
Reduce the volume. If distortion is still present, check the speaker
connections and ratings.
4. Short circuit detection
Indication -
Unit has switched off during power up. The Direct, Speaker A/B
and Mute light flashes together in the following sequence, four quick flashes
with long pause between flashes. Read below for more information.
Description -
During power up from Standby CAP5 performs a check on
the loudspeaker terminals to see if a short across the terminals has been
accidentally introduced. If the resistance measured across the loudspeaker
terminals is too low the unit will stay in Standby mode until the fault has been
removed and Power up is re-attempted.
Remedy -
There may be a short circuit between the loudspeaker terminals.
Check all loudspeaker connections before attempting to switch the unit out
of Standby.
5. Intelligent clipping detection
Indication -
Volume is reduced automatically.
Description -
CAP5 has the ability to detect when the amplifier starts to clip
or overdrive at its output, which can damage loudspeakers, and degrade the
sound. Clipping distortion is caused at high volume levels when the output
signal attempts to go outside the maximum voltage that the amplifier can
provide, causing the tops of the signal to flatten off.
When CAP5 detects clipping the volume will be automatically reduced down
until CAP5 detects an undistorted output.
Note: The clipping detection is disabled by default. The clipping detection can
be enabled in the Setup menu (see ‘Setup menu’ section).
Troubleshooting
There is no power
Ensure the AC power cord is connected securely.
Ensure the plug is fully inserted into the wall socket and is switched on.
Check fuse in the mains plug or adaptor.
There is no sound
Make sure the unit is not in Standby mode.
Check that source component is properly connected.
Check that your speakers are properly connected.
Make sure the selected speaker A/B light corresponds to the speaker
terminals that the loudspeakers are connected to.
Make sure unit is not in mute mode.
There is no sound on one channel
Ensure that balance control is in the correct position.
Check speaker connections.
Check interconnects.
There is a loud buzz or hum
Check turntable or tone arm for ground and connection lead fault.
Ensure no interconnects are loose or defective.
Ensure that your turntable is not too close to the amplifier.
There is weak bass or diffused stereo imaging
Ensure that speakers are not wired out of phase.
Direct, Speaker A/B and Mute light flashing
See section on CAP5 protection system.
The remote handset will not function
Check that the batteries have not expired.
Ensure that nothing is blocking the remote sensor.
For more frequently asked questions (FAQ’s), technical advice and information
on getting the most out of your CXA, please visit the Support section on
Cambridge Audio’s website:
www.cambridgeaudio.com/support
For all servicing, in or out of warranty, please contact your dealer.
