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Post subject: Intermittent windlike noise on Fender Red Knob Twin
Posted: Sat Dec 07, 2013 3:42 pm
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My 1990 Red Knob twin produces an intermittent wind-like noise after 5 minutes of warming up. The noise is produced randomly, sometimes it does it and sometimes it does not. Another problem it presents is with the Volume 1 control pot, Whenever you dial the volume in the clean cannel it produces a slight crackling noise. I have noticed it only does it when the amp is warming up. This noise is not present after 10 minutes of playing if you raise or lower the volume in the clean channel.

I have already changed all the power tubes, preamp tubes, power resistors and each and every filter capacitors in this amp.

I would appreciate if any experienced technician can guide me in the solution of this noise problems produced randomly.


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Post subject: Re: Intermittent windlike noise on Fender Red Knob Twin
Posted: Sat Dec 07, 2013 4:26 pm
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jalexquijano,

Try cleaning all the signal tubes (12AX7 & 12AT7) with a little contact cleaner (I like DeOxit GN5). Pull and insert each tube a couple of times, to work the cleaner into the socket tangs.

Hopefully, this will work. "Rushing" noise is usually a small signal tube issue.

Good luck. Keep us posted!


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Post subject: Re: Intermittent windlike noise on Fender Red Knob Twin
Posted: Sun Dec 08, 2013 3:33 am
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BMW2002Ti wrote:
jalexquijano,

Try cleaning all the signal tubes (12AX7 & 12AT7) with a little contact cleaner (I like DeOxit GN5). Pull and insert each tube a couple of times, to work the cleaner into the socket tangs.

Hopefully, this will work. "Rushing" noise is usually a small signal tube issue.

Good luck. Keep us posted!



+1
Clean 6L6's contact too .

No need expensive Deoxit and not easy to find . Any good contact cleaner will do the job . Like GC electronic or other.


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Post subject: Re: Intermittent windlike noise on Fender Red Knob Twin
Posted: Sun Dec 08, 2013 4:35 am
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Stratele, Deoxit GN5 can be bought from Amazon. Small 14gram applicator is all you will need for years (unless you repair amps on a regular basis).

Beware of cheap contact sprays. They often have solvents which may interact with plastic and rubber with heat & time.

http://www.amazon.com/DeoxIT%C2%AE-GOLD ... deoxit+GN5


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Post subject: Re: Intermittent windlike noise on Fender Red Knob Twin
Posted: Sun Dec 08, 2013 5:48 am
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BMW2002Ti wrote:
Stratele, Deoxit GN5 can be bought from Amazon. Small 14gram applicator is all you will need for years (unless you repair amps on a regular basis).

Beware of cheap contact sprays. They often have solvents which may interact with plastic and rubber with heat & time.

http://www.amazon.com/DeoxIT%C2%AE-GOLD ... deoxit+GN5



Amazon don't ship spay can outside USA . Same as all electronis store I see.

GC is a very good brand and cheaper than Deoxit . I have both product ( and more ) and I use Deoxit only when other don't work . Not very often .

Yes if you can have only one deoxit is the one .


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Post subject: Re: Intermittent windlike noise on Fender Red Knob Twin
Posted: Mon Dec 09, 2013 9:46 am
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Please bear in mind all the tube sockets are Brand new and were just replaced a couple of months ago. The eventual windlike roar noise must be produced by something else. Where else should i check?


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Post subject: Re: Intermittent windlike noise on Fender Red Knob Twin
Posted: Mon Dec 09, 2013 10:20 am
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jalexquijano wrote:
Please bear in mind all the tube sockets are Brand new and were just replaced a couple of months ago. The eventual windlike roar noise must be produced by something else. Where else should i check?


If you are sure your tubes are good and 6L6's bias not too hot.

A 1990 amp , which needed to replace all tubes socket !! I never saw that on 1960 amps and I saw a lots . What's happened to need this job ?

We need to know the story of this amp if it have some mods or ......


Some resistor can be noisy / defective ; Resistors on B+ , and all tubes's plate resistors .

Solder may be defective. Also check wiring dress especially if all the socket have been replaced.

Some inside photos may help.

Caution , lethal voltage in tubes amp even if disconnected since many hours or days.


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