[HAM] B3 Swell Capacitor

[Jordan Kersten]

If the trim screw is in it's full clockwise position (drive all the way down) I get no noise.  But I also get no drive.  I have played plenty of gigs with the drive level cranked and had no problems.  If you begin to turn the trim screw up, the noise will begin (but only if the foot pedal is fully depressed).




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> Date: Sat, 9 Feb 2008 16:10:17 +0100
> From: kuku at kukulies.org
> To: hammond at zeni.net
> Subject: Re: [HAM] B3 Swell Capacitor
> 
> Jordan Kersten wrote:
>> It is not a microphonic tube.  When the swell box is all the way up, you can tap on the tubes lightly and get to noise.  Tap on the swell box with the same amount of force, you can hear the taps and it will start to ring and have a low frequency feedback kind of sound and it will ring like this until you turn the pedal down.  It won't ring until it senses vibrations from the cabinet and it won't do it when the pedal is anywhere but in the full up position.  Adjusting the link between the swell capacitor and the foot pedal didn't work.  Does it seem like something is loose in there?
>>
>>
>>
>>
>> ----------------------------------------
>>   
>>> Date: Sat, 9 Feb 2008 10:16:57 +0100
>>> From: kuku at kukulies.org
>>> To: hammond at zeni.net
>>> Subject: Re: [HAM] B3 Swell Capacitor
>>>
>>> Jordan Kersten schrieb:
>>>     
>>>> Hi Guys.  I have a B3 that has a little problem.  When the expression pedal is all the way down, I get a sort of feedback noise.  It sounds like tube microphonics, but it is for sure the swell capacitor box.  The organ becomes very sensitive to cabinet vibrations and will make a low "feedback" type of sound.  It only happens then the pedal is all the way up and the drive level is anywhere above all the way down.  The expression pedal link is adjusted correctly and the trouble is definatly with the swell box.  Any ideas?
>>>>   
>>>>       
>>> If you are absolutely sure that it isn't a microphonic tube (6C4 tends 
>>> to be) and you have swapped tubes
>>> before then I would take out the AO-28 and examine the swell capacitor 
>>> house and the innards
>>> for cold solder joints and loose screws on the solder lugs.
>>> Ah, yes, check the trim capacitor screw if it got loose, first.
>>>
>>> Christoph
>>>     
> As I mentioned, you may check the trim capacitor screw in the swell 
> capacitor box, if it is there at all
> and how much it is turned ccw.
> 
> Then you may open the dust cover of the swell cap house with the AO-28 
> still seated in place and look for
> loose parts like the two solder lugs helkd by screws which may come loose.
> --
> Christoph
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