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K200b-2 [message #23756]

Sun, 06 September 2015 13:57

Iowa Boy
Messages: 767
Registered: June 2014

Senior Member

I've got an annoying hum on this amp at start up lately. Doesn't happen all the time but when you first turn it on even with no input and volume off, I get this hum that lasts for a few minutes and then goes away. At the same time there is a loss of power to the input. At first I thought I had a bad cord until I pulled the plug and hum was still there. Not loud and hum doesn't get louder when you turn any of the pots.

This amp runs about 4 to 6 hours a day since I am running i-heart radio from my computer to this amp. What's going on with this thing? Will the fuses I installed in all my cabinets protect the speakers from being blown?

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Re: K200b-2 [message #23759 is a reply to message #23756]

Sun, 06 September 2015 15:15

chicagobill
Messages: 2005
Registered: April 2003

Senior Member

You may have a dirty connection or a loose part on the power amp pc board or a failing component. What value fuse did you install in the speakers?

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Re: K200b-2 [message #23760 is a reply to message #23759]

Sun, 06 September 2015 15:25

Iowa Boy
Messages: 767
Registered: June 2014

Senior Member

fuses are 5 amp fast blow........think this was what Stevem had suggested to me earlier.

Amp works fine after it warms up a bit......and this has just started within the past week. My equipment is all in my lower half of the house but its' been hotter the all get out this week so AC has been on and there is also a dehumidifier in the room as well so know the problem is not a humidity issue.

What do you suggest I do to check this out. This amp gets a lot of use so I need to keep it operating without worrying about it blowing up on me.

[Updated on: Sun, 06 September 2015 15:29]

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Re: K200b-2 [message #23761 is a reply to message #23760]

Sun, 06 September 2015 19:01

carlc
Messages: 143
Registered: July 2006
Location: Summerville, SC

Senior Member

I have a new K100-2 that does a similar thing. When first powered on a loud crackling noise. None of the controls affect the noise or its volume; stays constant. After 2 or 3 minutes all is well.

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Re: K200b-2 [message #23764 is a reply to message #23761]

Sun, 06 September 2015 22:28

chicagobill
Messages: 2005
Registered: April 2003

Senior Member

In both of these cases something needs to warm up before it becomes stable.

One way to check this would be to take voltage readings around the amp when it is cold and not working normally. Then take the same readings when it warms up and see if there are any differences.

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