Mark Levinson 433 owner manual Extensive Protection, Mark Levinson, These fault conditions include

Extensive Protection

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Mark Levinson

The Nº433 is designed to shut itself down if it senses any of a number of fault conditions that could cause damage to itself or to associated loudspeakers.

These fault conditions include:

•the presence of DC (direct current) at the output

•demand for excessive current at the output, indicating a short- circuit

•over-voltage or under-voltage conditions (+/-10%) at the ~ac mains connector

•unsafe operating temperatures in any of several critical areas within the amplifier

In the case of either significant DC offset or an over-current condition, the amplifier will shut down to protect itself and the associated loudspeakers. The front panel indicator LED will blink rapidly, remaining lit about half of the time. To restore normal operation, power-down the amplifier using the power button, remove the cause of the fault, and wait five minutes before powering the amplifier back on.

If the ~ac mains connector voltage is too high or too low for safe operation, the amplifier will automatically enter sleep mode and the front panel indicator LED will blink rapidly, remaining on most of the time. The amplifier will not come out of sleep mode until the ~ac mains connector voltage is again within the normal operating range. For example, a 120V amplifier will operate between approxi- mately 108-132VAC; a 230V amplifier will operate between approximately 207-253VAC. Outside of these generous limits, the amplifier will enter sleep mode. Once the fault condition is removed, the amplifier can be taken out of sleep mode.

If the amplifier overheats despite its innovative heat sinking and cooling system, it will enter and remain in sleep mode until the temperature at the output heat sinks drops below 85°C (158°F or 358K). The front panel indicator LED will blink rapidly, remaining unlit most of the time. Once the fault condition is removed, the amplifier can be taken out of sleep mode.

In addition, the AC input to each transformer is fused to protect against excessive current conditions such as driving shorted outputs. Inrush limiting prevents premature aging of power supply components during power-up and switches off-line once the power supply has been charged.

Finally, the amplifier incorporates a controlled clipping circuit that prevents the output devices from saturating. The harsh, high- frequency harmonics generated by hard-clipped output devices are avoided by the wave-shaping action of the controlled clip circuitry.