[Boatanchors] voltage on the speaker???

[jeremy-ca]

Does that use a PM speaker or the older dynamic type that runs B+ thru the 
electromagnetic coil on the back of the speaker? There should be no voltage 
on the voice coil that is attached to the cone in either type.

Best bet is to unsolder some leads and Ohm it out.

Carl
KM1H


----- Original Message ----- 
From: "John King" <k5pgw at yahoo.com>
To: <boatanchors at mailman.qth.net>
Sent: Thursday, September 13, 2007 6:38 PM
Subject: [Boatanchors] voltage on the speaker???


> My "project of the day" is a Heath AR3 receiver. I
> have measured voltages and used a signal generator and
> signal tracer.
>
> Seems Ok until audio output stage. It is a 12V6 and it
> gets its' audio from the 12AV6 detector. I lose most ,
> almost all, of the signal at the 12V6 audio stage.
>
> Upon checking.....suspecting the speaker and/or audio
> output transformer, I checked for voltage on the
> speaker after getting an arc from one of the terminals
> with a probe.
>
> I measured the speaker terminal and had 288 vdc. on
> the speaker terminal. I suspect a short between the
> primary and secondary of the audio output transformer.
> WHAT DO YOU THINK??
>
> Surely there shouldn't be SUCH voltage on the speaker
> terminals.......I suspect that the speaker voice coil
> is also FRIED as well...WHAT DO YOU THINK?  The
> benefit of your KNOWLEDGE and EXPERIENCE WILL BE
> GREATLY APPRECIATED. 73, John, K5PGW
>
>
> 
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