Crown Audio MA-36X12 Troubleshooting, Indicators, Macro-Tech MA-24X6 & 36X12 Power Amplifiers

Macro-Tech MA-24X6 & 36X12 Power Amplifiers

5 Troubleshooting

5.1 Indicators

The front panel has several helpful indicator

LEDs (Figure 5.1).

The amber Enable indicator is provided to show the amplifier has been turned on (or enabled) and that its low voltage power supply and forced-air cooling system are working. It does not indicate the status of the high voltage supplies. For example, the Enable indicator will remain lit during unusual conditions that would cause the amplifier’s protection systems to put a high-voltage supply in “standby” mode (see Section 4.1.3).

The amber ODEP indicators confirm the nor- mal operation of Crown’s patented Output Device Emulation Protection circuitry. During normal operation, they glow brightly to show the presence of reserve thermal-dynamic energy. They dim proportionally as the energy reserve decreases. In the rare event that there is no reserve, the indicators turn off and ODEP proportionally limits the drive level of the out- put stages so the amplifier can continue safe

operation even when conditions are severe. (For a more detailed description of ODEP, see Section 4.1.1).

The ODEP indicator for the affected channel will turn off if a high-voltage power supply is put in “standby” mode, a high-voltage power supply fuse (or breaker) blows, or a transformer acti- vates its thermal protection circuitry (see Sec- tion 4.1.4). Both ODEP indicators turn off if the amplifier loses AC power, the power switch is turned off or the low-voltage power supply fuse blows.

The green Signal/IOC indicators show sig- nal presence, distortion and input overload. As signal presence indicators, they flash with nor- mal intensity in sync with the output audio sig- nals. As IOC (Input/Output Comparator) indicators, they flash brightly if there is any dif- ference between the input and output signal waveforms greater than 0.05%. Because tran- sient distortion happens quickly, a 0.1 second “hold delay” keeps the indicators on long enough to be easily noticed. The IOC function provides proof of distortion-free performance.

As input overload indicators, they flash brightly with a 0.5 second hold delay to show that an input signal is too large and must be clipped at the input.

Under conditions where one of the amplifier’s high-voltage power supplies is temporarily put in standby mode, the Signal/IOC indicators will stay on with full brightness. They will resume normal operation when the amplifier is no longer in standby mode.

The table in Figure 5.2 shows the possible states for the ODEP and Signal/IOC indicators. It also describes the conditions that may be associated with the different indicator states. The Enable indicator will be off with the first indicator state, “There is no power to the ampli- fier.” All other conditions in the table will occur with the Enable indicator turned on. It is impor- tant to note the possible states of the indicators in the rare event that you experience a problem. This can greatly aid in determining the source of problems. Please contact your local Crown representative or our Technical Support Group for further assistance.

Figure 5.1Indicators

Operation Manual page 17