Halcro DM38 Owner's Manual page 12

dm38
Unusual output conditions
The vast majority of amplifier faults show up as high positive or negative d.c. output
voltages. An independent circuit in the Halcro amplifiers senses any unreasonable d.c.
output voltage and switches the amplifier off if this occurs.
Likewise, if any excessive output current flows for an extended length of time, this
also implies a fault and an independent circuit measures this and will shut down the
amplifier.
Power supply output current limiting
To further reduce the possibility of fault conditions causing substantial damage, the
power supply is limited in its maximum available average output current. Note that
this level is higher than the amplifier's normal current limiting conditions. The power
supply limit will only cut in under fault conditions.
Internal power supply protection
There are numerous power supply protection circuits, for example:
Two independent over temperature cut outs.
Two independent master clock fault sensing circuits.
All power supplies, including those for "housekeeping" standby, active power
factor correction and switch mode power etc check for under/over voltage and
over current conditions.
The small signal power supplies have transient diode over-voltage protection.
Mains transient overload protection
The mains input is protected against all but the most severe mains input transients.
Three independent circuits achieve this: two surge absorbers and high energy
inductive filtering.
Input overload protection
The inputs have over-voltage protection circuits, which will handle most typical input
overloads.
Amplifier inter-stage protection
In addition within the amplifier stages, there are more than a dozen protection
circuits.
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