Xref: utzoo sci.electronics:5301 rec.audio:11041 rec.ham-radio:8898
Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!bloom-beacon!gatech!rayssd!rayssdb!iws
From: iws@rayssdb.ray.com (Ihor W. Slabicky)
Newsgroups: sci.electronics,rec.audio,rec.ham-radio
Subject: Re: 60 Hz hum filter
Summary: thanks - now what?
Keywords: any ideas
Message-ID: <2322@rayssdb.ray.com>
Date: 22 Feb 89 17:00:33 GMT
References: <2313@rayssdb.ray.com>
Sender: root@rayssdb.ray.com (UNIX System Administrator @ Raytheon Company, Portsmouth RI)
Organization: Raytheon Company, Portsmouth RI
Lines: 30

In article <2313@rayssdb.ray.com>, iws@rayssdb.ray.com (Ihor W. Slabicky) writes:
> 
> Can anyone send me a schematic or info on broadband noise filters
> that will filter out 60 Hz hum on the 120VAC line?  Some background: 
> I use a portable stereo cassette recorder to record music off my
> receiver.  When the recorder is powered from the AC line, I can hear
> lots of 60 Hz being recorded on the tape.  Moving the recorder, cables,
> or power cord around tends to lessen the hum.  When I record using the
> batteries, no hum.  Also, when I playback, if I put the INPUT switch
> on the recorder to the MIC position, no or very little 60 Hz hum is
> heard, but when the INPUT switch is set to LINE, lots of hum.  Ideas?

Well, thanks to everyone who responded.  The two problems suggested are:

1 - a ground loop or faulty cables.  Recommendations were to check the
    cables and switch around the plugs at the wall or to other outlets.
    I tried both of these, and this did not solve the problem.  So...

2 - filtering capacitors going bad in the tape recorder's power supply
    (AC to DC) conversion.  This may be the problem.  The recorder is
    almost 15 years old.  Before I go and take it apart, any ideas on
    how to test the capacitors using a volts/ohms/DC amps meter to see
    that they are bad?  Any ideas on which type of capacitors to use
    as replacements (obviously same or higher ufd value and same or
    higher voltage value)

Thanks for your advice - Ihor

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