Crown Audio MA-602, MA-1202 operation manual Troubleshooting

MA Series Power Amplifiers

6 Troubleshooting

The table in Figure 6.1 shows the possible states for the ODEP and Signal/IOC indica- tors. It also describes the conditions that may be associated with the different indica- tor states. The Enable indicator will be off with the first indicator state, "There is no power to the amplifier." All other conditions in the table will occur with the Enable indi- cator turned on. It is important 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 6.1

Macro-Tech ODEP

and Signal/IOC Indicator Status

Indicator Status		Amplifier Condition
ODEP	OFF	There is no power to the amplifier and all indicators are off, including the Enable light.
		Possible reasons: (1) The amplifier’s Enable switch is off. (2) The amplifier is not plugged into the power
SIGNAL / IOC	OFF	receptacle. (3) The AC circuit breaker has been tripped. (4) The amplifier’s low-voltage power supply
		fuse has blown.
ODEP	ON	Normal operation for a channel with NO audio output. Possible reasons: (1) There is no input signal.
		(2) The input signal level is very low. (3) The channel’s level control is turned down.
SIGNAL / IOC	OFF
ODEP	ON	Normal operation for a channel with audio output. The ODEP indicator will remain at full intensity
		to show that there is reserve thermodynamic energy, and the Signal/IOC indicator will flash with normal
SIGNAL / IOC	Normal	intensity to show that the channel has audio output.
ODEP	ON	The channel’s output is exceeding 0.05% distortion. The input signal level is too high and IOC is
		reporting either an input overload or output clipping.
SIGNAL / IOC	Bright	OR
		Channel 2 only: The amplifier is in Parallel-Mono mode. The channel 2 Signal/IOC indicator always
		turns on to full brightness whenever the amplifier's stereo/mono switch is set to Parallel-Mono mode.
ODEP	OFF	The amplifier channel is in standby mode. Possible reasons: (1) A PIP module like an
		IQ-PIP-Lite has turned off the channel’s high-voltage power supply. (2) The amplifier has just been
SIGNAL / IOC	Bright	turned on and is still in the four second turn-on delay. (3) The DC / low-frequency protection circuitry has
		been activated. (4) The fault protection circuitry has been activated. (5) The transformer thermal
		protection circuitry has been activated.
		OR
		A channel’s fuse has blown or breaker has tripped. Transformer overload can cause a channel’s
		internal fuse for its high-voltage supply to blow in a Macro-Tech 602 or 1202, and it can
		cause the channel’s circuit breaker to trip in a Macro-Tech 2402.

OR

ODEP limiting has been activated. Possible reasons: (1) The amplifier’s air filters are blocked and need to be cleaned. (2) There is insufficient cooling because of inadequate air flow or air that is too hot.

(3)The load impedance for the channel is too low because the output is shorted or the amplifier is driving too many loudspeakers for the selected stereo/mono mode. (4) The amplifier channel is continuously being driven to very high output levels.

ODEP	OFF	ODEP limiting is about to begin. Possible reasons: (1) The amplifier’s air filters are blocked and need
		to be cleaned. (2) There is insufficient cooling because of inadequate air flow or air that is too hot.
SIGNAL / IOC	Normal	(3) The load impedance for the channel is too low because the output is shorted or the amplifier is
		driving too many loudspeakers for the selected stereo/mono mode. (4) The amplifier channel is
		continuously being driven to very high output levels.

page 18 Operation Manual