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Crackling/Static in Right Channel Only - KR-6160

S

Silver9807

New Member
There's a crackle static sound coming out of the right channel on a KR-6160. It's not dependent on volume level; whether volume is zero or maxed out the static remains the same level. All inputs have this sound, changing mode to right, left, rev - all of them the static remains in the right channel. You can also hear it when you insert headphones. Sound remains regardless if I'm using A, B, or C speakers. Switching the balance to full left channel, cutting out the right channel completely, has no effect either - sound remains in right channel at same level.

So far all I've done is clean all the switches and potentiometers very well, but the problem persists.

Your thoughts?
 
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Differential pair on the right channel.

They may be some of the "known to go bad" transistors depending on age.
 
I'm working on a 5150 right now and it had several bad 2SC458 transistors. I'm not positive the 6160 has them but it probably does. Those transistors are known troublemakers and there's a good chance replacing them will take care of your problem. I used KSC1815s as the replacement and they seem to work.
 
Thanks guys for your input - thanks so much for the details Brian1970. Is there a way to determine whether a transistor is bad or not using a multimeter?
 
There is no differential pairs in the KR-6160. You should replace Qe01-02-03-04 with Ksc1815 as Brian said.
 
Those are not classic long tailed pairs, but they serve the same function of voltage amplification. Quasi-complimentary cap coupled amp.

Those 2SC458s very often get noisy and produce hiss, pops, and snaps. Great transistors 553 years ago, not so hot now!
 
Silver9807 said:
Thanks guys for your input - thanks so much for the details Brian1970. Is there a way to determine whether a transistor is bad or not using a multimeter?
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You can figure out if it's completely bad with a multimeter that has a diode check function, but you won't be able to tell if they're noisy or creating snaps, crackles, and pops. Those transistors are known to go bad and are your most likely problem though. If you google "transistor test with multimeter", you'll get a bazillion things to read about it.
 
One of the "oh, ah hah" moments I had with my KR-6160 was the MIC input is always on and that tiny circuit has a noisy 2SC458 in it. That was where my noise was coming from. Replace the 458, no more noise.
 
ecluser said:
Maybe but a can of freezer spray is as much expensive as 1000 noise free transistors. It is the festival of 2sc458 in this receiver.
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unless you get creative and use canned air from the pound shop and hold it upside down . that's if you have a pound shop that is or maybe a dollar shop .
 
I just finished replacing all the 2SC458's, got those suckers in the MIC input dlucy and so far the background seems very quiet now, dare I say maybe even absent - amazing. I'm worried the gremlin will come back once its had a chance to warm up a while,we'll see how it goes. Thanks everyone for the help.

There's something else I'm wondering if you'd know about. And this started happening before replacing the 2SC458's, but when I turn on the receiver there's soft static in the right channel only that slowly fades to clear after 7 seconds or so. It sounds like snow. Then its completely clear, but if I turn it off the same thing happens - snow for about 7 seconds after the receiver is off. Does anything immediately spring to mind?
 
Silver9807 said:
I just finished replacing all the 2SC458's, got those suckers in the MIC input dlucy and so far the background seems very quiet now, dare I say maybe even absent - amazing. I'm worried the gremlin will come back once its had a chance to warm up a while,we'll see how it goes. Thanks everyone for the help.

There's something else I'm wondering if you'd know about. And this started happening before replacing the 2SC458's, but when I turn on the receiver there's soft static in the right channel only that slowly fades to clear after 7 seconds or so. It sounds like snow. Then its completely clear, but if I turn it off the same thing happens - snow for about 7 seconds after the receiver is off. Does anything immediately spring to mind?
Click to expand...
need to replace the 2sc871(x4) in the tone amp as well. they can cause static

there are 4 more in the phono stage as well

there are a bunch of 458s in the tuner also

ksc1845 are the replacement
 
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