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KLH Model 21 help



 
 
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  #1  
Old March 16th 18, 03:22 PM posted to rec.audio.tech
[email protected]
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Posts: 1
Default KLH Model 21 help

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..
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  #3  
Old March 18th 18, 01:08 AM posted to rec.audio.tech
~misfit~[_3_]
external usenet poster
 
Posts: 66
Default KLH Model 21 help

Once upon a time on usenet Trevor wrote:
> On 17/03/2018 1:22 AM, 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? :-)
>
> Trevor.


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...
--
Shaun.

"Humans will have advanced a long, long way when religious belief has a cozy
little classification in the DSM*."
David Melville (in r.a.s.f1)
(*Diagnostic and Statistical Manual of Mental Disorders)


  #4  
Old March 18th 18, 08:12 AM posted to rec.audio.tech
Trevor
external usenet poster
 
Posts: 2,709
Default KLH Model 21 help

On 18/03/2018 11:08 AM, ~misfit~ wrote:
> Once upon a time on usenet Trevor wrote:
>> On 17/03/2018 1:22 AM, 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. :-)

Trevor.


  #5  
Old March 19th 18, 03:05 AM posted to rec.audio.tech
~misfit~[_3_]
external usenet poster
 
Posts: 66
Default KLH Model 21 help

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, 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.

Cheers,
--
Shaun.

"Humans will have advanced a long, long way when religious belief has a cozy
little classification in the DSM*."
David Melville (in r.a.s.f1)
(*Diagnostic and Statistical Manual of Mental Disorders)


  #6  
Old March 19th 18, 10:36 AM posted to rec.audio.tech
Trevor
external usenet poster
 
Posts: 2,709
Default KLH Model 21 help

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, 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.

  #7  
Old March 20th 18, 01:01 AM posted to rec.audio.tech
~misfit~[_3_]
external usenet poster
 
Posts: 66
Default KLH Model 21 help

Once upon a time on usenet Trevor wrote:
> 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, 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.


Nor have I - at least not for posting. Once or twice I've tried to search
for an old post. The *******s took over Deja news archives and butchered
them!
--
Shaun.

"Humans will have advanced a long, long way when religious belief has a cozy
little classification in the DSM*."
David Melville (in r.a.s.f1)
(*Diagnostic and Statistical Manual of Mental Disorders)


  #8  
Old March 21st 18, 11:04 AM posted to rec.audio.tech
geoff
external usenet poster
 
Posts: 1,356
Default KLH Model 21 help

On 18/03/2018 1:08 PM, ~misfit~ wrote:
> Once upon a time on usenet Trevor wrote:
>> On 17/03/2018 1:22 AM, 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? :-)
>>
>> Trevor.

>
> 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...
>


Jeeze Shaun - you stalking me or something - you're everywhere !

geoff
  #9  
Old March 24th 18, 06:43 AM posted to rec.audio.tech
~misfit~[_3_]
external usenet poster
 
Posts: 66
Default KLH Model 21 help

Once upon a time on usenet geoff wrote:
> On 18/03/2018 1:08 PM, ~misfit~ wrote:
>> Once upon a time on usenet Trevor wrote:
>>> On 17/03/2018 1:22 AM, 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? :-)
>>>
>>> Trevor.

>>
>> 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...
>>

>
> Jeeze Shaun - you stalking me or something


Says the man replying to me...

> - you're everywhere !


I prefer omnipresent. ;-)
--
Shaun.

"Humans will have advanced a long, long way when religious belief has a cozy
little classification in the DSM*."
David Melville (in r.a.s.f1)
(*Diagnostic and Statistical Manual of Mental Disorders)


 




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