[Amps] Strange Problerm

[Richard]

>Hi Amps Readers,
>
>I will chime in here because I am the one who made the comment.  What I
>meant by the term "wild leg" is that one leg of the 240VAC mains may be
>unbalanced with respect to the other leg (or neutral) in a single-phase
>typical residential set-up..

It matters not whether the legs are balanced with tespect to neutral 
because the 240V primary is not connected to the neutral wire.  Mr. Rauch 
was right. 

>I know the term "wild leg" is normally used when talking about 3-phase mains
>where one of the legs fluctuates in voltage based on phase angle.
>
>I used the terms interchangeably in the conversation, but should have been
>more specific.
>
>As far as blowing one side of the capacitor bank, something must be causing
>a large DC voltage rise.  I doubt it is AC killing the caps from the SB-220
>(if he has one of my FB-220 filter packs installed) because they are
>protected with diodes across each cap to protect from AC getting into the
>caps.

agreed
>
>If the problem is evident in two different amps running from the same house
>circuit, a problem with the incoming mains is probably indicated.  What the
>problem is, I don't know.
>
One, open V-equalizer-resistor would cause one cap to fail/short and this 
would dominos-fail the remaining caps in that string.  

>As far as a builder, yes, I am an experienced builder.  As for a complete
>Ph.D. level of theory, I don't have it and don't proclaim to.
>
>Tom or Rich, if you guys have an idea as to why this could occur, please let
>me and the list know.  It sure does sound like something causing DC voltage
>over and far above the ratings of the caps in the side of the filter bank
>that keeps blowing.
>
>Regards,
>Jeff Weinberg  W8CQ
>Harbach Electronics
>(317) 892-2641
>harbachelectronics@tds.net
>http://www.harbachelectronics.com
>---------------------------------------------------------
>
>----- Original Message -----
>From: "2" <2@vc.net>
>To: "Tom Rauch" <W8JI@contesting.com>; " AMPS" <amps@contesting.com>;
><w5asp@earthlink.net>; <rauch@contesting.com>
>Sent: Friday, June 07, 2002 8:41 AM
>Subject: Re: [Amps] Strange Problerm
>
>
>>
>>
>> >> Twice within the past six months we have had amplifiers fail due to
>> >> the loss of all of the power supply filter capacitors in one "bank" of
>> >> the supply.  Both amplifiers (an Alpha 76 and a SB-220) were being run
>> >> on 240 V AC.  In both cases the filter capacitors were "relatively"
>> >> new.
>> >
>> >...
>> >> However, a recent comment by an experienced HV power supply builder,
>> >> has brought up the subject of a possible "wild leg" in the 240 V AC
>> >> line to which the amps were attached.  According to this suggestion, a
>> >> large transient VOLTAGE swing on one leg of the 240 V mains put an
>> >
>> >Bad answer. He might be a good builder, but regretfully he must not
>> >fully understand how supplies and power mains work.
>> >.
>> Amen, Mr. Rauch.
>>
>> -  R. L. Measures, a.k.a. Rich..., 805.386.3734,AG6K,
>> www.vcnet.com/measures.
>> end
>>
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>
>
>


-  R. L. Measures, a.k.a. Rich..., 805.386.3734,AG6K, 
www.vcnet.com/measures.  
end