K50-2 bad Hiss (Help) [message #7303] |
Sat, 12 August 2006 23:59 |
tweed112
Messages: 34 Registered: January 2006 Location: Mass
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I have many Kustoms, There is one I have with a bad hiss K50-2
I have read all the forums and looked at everything on this website...everyone seems to say this is normal with old kustoms?
Its hard for me to believe that my amp was sold new with this problem? you could never mic up the amp?
I am a amp tech and Ive spent 3 days with this amp everything checks out good, I have the schematic all voltages and componets check out good, I put on a 3 prong ac plug and there is nothing wrong with this amp ( that I can see) still this hiss is pretty bad!
So....heres the question....
Are you guys saying this is just the way old kustoms are?
I have 8 different kustoms all are old some have a slight hiss and some have almost no hiss at all....I love these amps and am addicted to collecting them but this hiss thing is about to stop me putting money into buying anymore..
Any comments would be helpful......thanks
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Re: K50-2 bad Hiss (Help) [message #15263 is a reply to message #7303] |
Wed, 16 February 2011 16:49 |
chicagobill
Messages: 2005 Registered: April 2003
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OK, it's the first input stage. Ooh, the volume control is at the head of the circuit, just like a Frankie circuit.
Based on the circuit, there is almost no voltage there, and it isn't being stressed at all, so I would think that nearly any p-channel fet would work there. Did you check the pinout for the new one before you installed it? The gate is most important, the drain and the source can be interchanged in most cases.
As for the noise, do any of the controls change its' sound? Try to isolate it by sections and then try heating or cooling or parts to see if any react in a good or a bad way.
The service note talked about high value carbon resistors failing and causing noise. The only high value resistor I can see there is R22.
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