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Viewing 1 to (9 Total) KN1000 buzzing |
Total Posts: 5
Joined: March 8, 2018
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I hear a constant buzzing coming form one speaker.
Looking for suggestions as to what it might be as well as whether it is easy to fix. Could I do it? (very basic skills!) Or is there anyone close to Norwich who could fix it for me.
Any help appreciated.
Tags:
KN1000
Posted on March 8, 2018 at 3:57 PM
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United Kingdom
Total Posts: 360
Joined: June 8, 2014
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Re: KN1000 buzzing
Hi Bev, Welcome to the site, sorry you are having trouble with your keyboard. You say your speaker is buzzing, is this when you have the keyboard just sitting not being played but switched on or is it only when you are playing it. Another thing to check is the buzz still audible if you use headphones. These questions are just to help to point us in the right direction.
Regards John Dawson (admin)
Posted on March 8, 2018 at 6:01 PM
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United Kingdom
Total Posts: 166
Joined: January 12, 2015
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Re: KN1000 buzzing
Hi there
One speaker buzzing in this particular keyboard is likely to be in whichever power amp that is at fault. The amps in this case are relatively straight forward. It might be an idea to check the headphone output as it is a separate circuit (rather than being tapped off the speaker outputs) and therefore would let us know if the fault is before the power amp or within it. If the buzz is there on the headphones then the fault is before the power amps and ironically it could be in the noise reduction circuit. The main volume control is what is known as a voltage controlled amplifier so if the buzz goes down if you turn the volume down to zero then the chances are it is in the circuitry prior to the volume control. if it stays the same and is on headphones too then the place to look is the VCA chips themselves or the buffer opamps so IC 10 or 11 would be where to look. If you can do the changes then it is a place to start. I would take the opportunity to replace several of the capacitors in the power supply namely C9 (6volt 1000uf but upgrade to 16v 1000uf), C7 and 8 both 35v 10uf, C3 35v 2200uf, and C4 35v 3300uf.
Don't attempt it if you have never done electronic repairs before. You can do more damage and wreck a machine just taking the top off so to go in with soldering iron blazing is not good if you have never attempted repairs before.
Let me know what you find. Headphones buzz on or off?
Does it go up and down with the volume?
Regards
Dave
Posted on March 12, 2018 at 9:20 PM
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Total Posts: 5
Joined: March 8, 2018
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Re: KN1000 buzzing
The buzzing is the same volume no matter what the volume setting is.
I don’t hear the buzzing through the headphones.
Posted on March 12, 2018 at 10:53 PM
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Total Posts: 5
Joined: March 8, 2018
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Re: KN1000 buzzing
Oh and buzz is on whether I am playing or not.
I hope that answers the questions.
I am no technician and certainly not going to attempt soldering!!
Posted on March 12, 2018 at 10:57 PM
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United Kingdom
Total Posts: 166
Joined: January 12, 2015
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Re: KN1000 buzzing
So in the output circuits then.
You could find a local TV engineer to look at it although they are few and far between now and usually don't want to know about anything that isn't in their field. Alternatively you could bring it to me but its a long journey as I am in Kent.
Posted on March 13, 2018 at 8:01 AM
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Total Posts: 5
Joined: March 8, 2018
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Re: KN1000 buzzing
Kent is a bit too far for me to bring it 
So its not the amps then, but something much trickier?
I will have to see if anyone on Facebook can help.
Thanks for your help
Bev
Posted on March 15, 2018 at 10:48 AM
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United Kingdom
Total Posts: 166
Joined: January 12, 2015
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Re: KN1000 buzzing
Ouch! Good luck with that! I have found most so called experts on FB are very far from that! I have been doing this since my early teens and I am now 59 so I have seen my share of "expert" repairs with sticky tape and matchsticks! First thing you do when talking to any of these guys is to ask them at what point will you be PAT certifying the equipment. If they don't do it then stay away!
Good luck
Regards
Dave
Posted on March 15, 2018 at 3:10 PM
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Total Posts: 5
Joined: March 8, 2018
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Re: KN1000 buzzing
Lol, yes I shall be careful and research anyone who says they can help. A few friends are musicians and so hopefully they will know someone trustworthy who can help. If only you were a bit closer.
Thanks for the advice.
Posted on March 15, 2018 at 3:52 PM
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