# Faulty receiver or power amp?



## Fincave (Apr 20, 2006)

I seem to have a problem! I have a Yamaha receiver (RX-V 640) to which I have a power amp connected, Advance Acoustic MAA 405. The power amp is connected to the receiver's pre outs and feeds my mains. The problem: I had switched off the power amp yesterday using the switch at the back, not the standby. Today I wanted to listen to music, powered up my system forgetting to turn on the power amp, however music still played as normal. As I understand these things my mains should have remained silent as the power amp was off. I switched the power amp on and whilst it normally makes a click sound when being switched on or off, today it did not. I switched it on and off several times, even while off I could listen to music. The power amp did make the click sound after being powered on after about the sixth attempt and then after being switched off I could no longer hear anything through my mains. Now everything seems to be working as normal, if the amp is off I hear nothing htrough the mains, if it is on I hear music. According to my thinking there is a fault with the power amp? Any suggestions??


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## Sonnie (Apr 11, 2006)

It does sound like a faulty power switch to me, but at least it's working okay for now.

I'm assuming you normally use the standby instead of the rear power switch. If that is still working, I would simply start using it and not worry about that power switch.


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## Fincave (Apr 20, 2006)

Do not know if the power switch is faulty, it did switch the power amp off completely, no standby light was on but I could still hear the music normally. Surely with the power amp being completely switched off I should not have anything coming through the mains? I have a trigger connected between the two and this powers the amp on once the receiver is powered up. I have now tried a few times having the receiver on and switching the amp into standby and the mains are then switched off as they should be. My mains are only connected to the speaker terminals on the power amp.


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## phogandive (May 3, 2006)

Fincave said:


> Do not know if the power switch is faulty, it did switch the power amp off completely, no standby light was on but I could still hear the music normally. Surely with the power amp being completely switched off I should not have anything coming through the mains? I have a trigger connected between the two and this powers the amp on once the receiver is powered up. I have now tried a few times having the receiver on and switching the amp into standby and the mains are then switched off as they should be. My mains are only connected to the speaker terminals on the power amp.


Hi,
Another thing you can try is to physically unplug the power cord of the power amp, then you KNOW it's not getting power. If that stops the sound from the mains, then it sounds like the power switch on the amp is stuck on, even when stwitched off (I've had this happen, as when you first switch the amp on, there is a huge inrush current to charge the filter capacitors in the power supply, and that current surge can sometimes weld the switch contacts together, causing it to be stuck on.)

Peter


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## Fincave (Apr 20, 2006)

Thanks for the reply! It does make sense that the switch may be stuck on, the only thing is that now it is working normally, I have tried quite a few times to get it to do the same thing again but it just will not. Will try a few more times and see if the problem crops again, am planning on contacting the store where I bought it from just to see if other people have experienced similar problems.


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