From: trevor@home.net   
      
   On 19/03/2018 1:05 PM, ~misfit~ wrote:   
   > Once upon a time on usenet Trevor wrote:   
   >> On 18/03/2018 11:08 AM, ~misfit~ wrote:   
   >>> Once upon a time on usenet Trevor wrote:   
   >>>> On 17/03/2018 1:22 AM, audioguymn@gmail.com wrote:   
   >>>>> On Friday, July 27, 2001 at 2:34:43 PM UTC-5, MitchSF wrote:   
   >>>>>> Hi, I'm almost finished restoring a KLH Model 21.  I replaced   
   >>>>>> three transistors on the RF board and it now works!   
   >>>>>>   
   >>>>>> The only problem left is a hum from the audio board.  I   
   >>>>>> disconnected it from the input to the board so I'm sure it's not   
   >>>>>> coming from anywhere else.  I replaced the filter capacitor and   
   >>>>>> all electrolytics on the audio board and it's a little quieter,   
   >>>>>> but still there.  The level of the hum doesn't change with the   
   >>>>>> volume control.   
   >>>>>>   
   >>>>>> Any hints would be appreciated!   
   >>>>>>   
   >>>>>> Thanks, Mitch   
   >>>>>   
   >>>>> Hi Mitch. The power supply filters, either of the black color   
   >>>>> are/were a common failure item. They should be replaced. However,   
   >>>>> note that the positive terminal was marked with the stripe as we   
   >>>>> would now associate with the negative terminal. It is also   
   >>>>> important that you do not increase the value of these capacitors   
   >>>>> as the power supply can't handle the extra in-rush and operational   
   >>>>> paramete5rs. Mark - Former National Service Manager, KLH Cambridge.   
   >>>>   
   >>>> Wonder whether he even still has it 17 years later? :-)   
   >>>>   
   >>>   
   >>> Probably not - at least not with the issue still (however somebody   
   >>> might...) It's good to have a knowledgeable person posting here so let's   
   >>> not   
   >>> be too harsh...   
   >>   
   >> True, might help someone else, and I wouldn't want to discourage that.   
   >> I'm just amazed at how many people answer 20 year old posts because   
   >>   they don't even realise it. :-)   
   >   
   > As you likely know it's usually because these days most people don't   
   > actually use usenet - they use parasitic web forums that don't delete old   
   > posts in an effort to appear to have lots of content.   
   >   
      
   Yes I know, and many are from Google Groups, but I would have thought   
   the date was still shown somewhere? But then I've never used it myself.   
      
   Trevor.   
      
   --- SoupGate-Win32 v1.05   
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