Manual

27
CAP5
Last updated: June 6, 2022 08:58. Revision #4897
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 front panel LED 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 front panel LED 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 front panel LED 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 front panel LED 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