vintage sony fm tuner- no stereo, only mono!

Archived from groups: rec.audio.tech (More info?)

This could be caused by a number of things. A short between the drivers and
the speakers could be bleeding current equally between the two. It could be
also on the input side. The switch itself could be shorting the two feeds
together. You'd need to open it up and test the signal path to find shorts.
Good luck if there're capacitors in the line...

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____________________________________

Brandon Anderson
Lighting, Sound, and Video

http://www.bdanderson.com/


"Michael Salmons" <salmonsm@missouri.edu> wrote in message
news:a38b51d9.0406160856.3d01a110@posting.google.com...
> Hello,
>
> I've gotten my hands on a very nice older Sony FM tuner (ST-A6B). It
> has a few problems but the most troubling is it will only do mono, not
> stereo. It has a mode switch with three positions: mono, hi-blend and
> stereo. They are all identically mono EXCEPT in hi-blend, imagining it
> as a stereo image, the sound is moved over a bit to the left, but
> still with no channel separation.
>
> This, as I stated before, is an older tuner, probably made in the
> mid-seventies, all analog. Does this sound like the malfunction of a
> certain part that I could replace? Could it be the MPX chip? Or maybe
> the mode switch is bad?
>
> Thanks,
>
> Michael Salmons
> salmonsm @ missouri . edu

Archived from groups: rec.audio.tech (More info?)

It's not uncommon on older tuners for the VCO adjustment to be a bit off. If
you can identify it, try rocking the adjustment back and forth a bit. When
the Stereo indicator comes on reliably, you're done.

Mark Z.

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"Michael Salmons" <salmonsm@missouri.edu> wrote in message
news:a38b51d9.0406160856.3d01a110@posting.google.com...
> Hello,
>
> I've gotten my hands on a very nice older Sony FM tuner (ST-A6B). It
> has a few problems but the most troubling is it will only do mono, not
> stereo. It has a mode switch with three positions: mono, hi-blend and
> stereo. They are all identically mono EXCEPT in hi-blend, imagining it
> as a stereo image, the sound is moved over a bit to the left, but
> still with no channel separation.
>
> This, as I stated before, is an older tuner, probably made in the
> mid-seventies, all analog. Does this sound like the malfunction of a
> certain part that I could replace? Could it be the MPX chip? Or maybe
> the mode switch is bad?
>
> Thanks,
>
> Michael Salmons
> salmonsm @ missouri . edu