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XLS 5000 get very hot without any audio signal applied


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#1 techie47

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Posted 07 September 2013 - 08:10 PM

I have six xls5000 and noticed one of them gets hot quickly without any signal applied to it. I can feel very hot air at the fan. The botttom and top of the amp is hot  where the heatsink is.   The amp power up fine and doesn't cut off,but it just get hot and has me worried. I am wondering if it's a bias or oscillation problem.   I was just wondering if anyone has experienced this issue before I go inside it.

#2 joust

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Posted 10 September 2013 - 09:24 AM

Hello techie,

How hot is 'hot'? Did you measure the heat with a thermal thermometer?
If the amp is not loaded does it still heat up?
Does the amp have inputs connected when it heats up? If inputs are removed does it continue to heat up?
It may be a bias issue; It may be oscillations! I would first verify if the power supply is operating normally.
Then, is it Ch1 or Ch2 (or both!) that is causing this heating issue?

Alain

#3 techie47

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Posted 12 September 2013 - 08:37 PM

Hello Alain,
It get very hot to the touch where the heatsink is in the back of the amp in less than fifteen minutes. No, I didn't measure thet emp with a thermal thermometer as yet. The top and bottom of the amp gets hot where the output stage is. The fan is blowing out very hot air when you put your hand  where  the air comes out. The strange thing is no  input jacks  or speakers are connected to it and it gets hot. Thats why I am wondering if it's oscillations or a bias problem it has. I guess I will have to pull out the oscilloscope and multimeter soon.

#4 joust

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Posted 13 September 2013 - 07:34 AM

Since it appears that 'both' sides seem hot, I would first try to see if something common to both channels is problematic: regulators (very possible!), perhaps some filter caps have openned. I'm not sure if this unit has a mains voltage changer switch, but verify that the amp is configured for your country's voltage.
Now, why would heatsinks get very hot? Perhaps because some load is applied to the output section... Verify the outputs for any visible shorts, or that you have a large offset voltage;  Yep, I believe it's now time for troubleshooting 101! Good luck and patience!

Alain

#5 techie47

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Posted 13 September 2013 - 09:27 PM

Thanks a million for your input.      The amp is wired for 120 vac. There is no more than  6 millivolts max on each channel when it's measured with a multimeter.  I will check grounds and supply voltage on the power supply capacitors and then the output stage  bias next.