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Macrotech 2401 in standby mode


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#1 Will van Nus

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Posted 19 September 2011 - 06:23 AM

Hello, one of my four Amcron 2401 amps has been running for about half an hour on a normal 8 ohm load, for background music only. Both channels driven, same type of speakers and not loud, so to say. Suddenly, the right channel went dead, the ODEP led went out and the green led was lit bright. The left channel remained in good working order. Before this all happened I haven't heard funny noises or any distortion in the sound.
According to the manual this is the StandBy Mode. When I switch the amp on now I can hear the relay click every 4 seconds so apparenty the circuitry keeps checking whether the problem is solved. Can anyone tell me what might have happened and what there's to do now? Is  there some reset option? Switching on and off doesn't help, the speakers are ok, speakerleads aswell, inputleads also, I've checked all cables. The unit (clean as new) has got the PIP CLP module fitted an I've cleaned the contacts of that multiconnector.
HELP please....



#2 kevvywevvywoo

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Posted 19 September 2011 - 12:47 PM

The amplifier has detected a fault in that channel and has switched it off to minimise further faults. Sometimes the relay will click in-out like that as it attempts to power up that side but can't. You will need to fault-find, component-wise  on the channel.

#3 Will van Nus

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Posted 19 September 2011 - 02:54 PM

Thanks, how and where to start this? I'm not really a repair tech. There's no voltage at all at the transformer.....

#4 kevvywevvywoo

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Posted 19 September 2011 - 04:11 PM

To be brutally honest, fault finding a macrotech is not for the rookie, but an experienced tech. They are complicated, and contain high voltage.

The power for the mains transformers is switched by relays. Those relays will switch off the power again if a serious fault in the output stage is detected, for example high DC offset caused by shorted output transistors or faulty drive. This is a job normally done by speaker relays in other amplifiers but the macrotech does it on the mains side.

Tracking that fault involves testing transistors, diodes, resistors etc and replacing with correct types in the proper manner.

If you are tempted to have a poke around anyhow, discharge the bus caps before inserting fingers or tools. Pull the wall plug before removing covers.






#5 Will van Nus

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Posted 19 September 2011 - 04:56 PM

Thanks, I guess you've just saved my life. And I like you already for being brutally honest. Ok. This is not for me. I'll have it sent to the Crown representative in Holland.
Have a nice day ...!