Sony Detector transformer needed

Tim Schwartz

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Oct 27, 2015, 8:04:42 AM10/27/15

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Hello all,

I need a 1-403-290-11 detector transformer which after 35 or 40 years
is no longer available from Sony. It was used in the tuner section of
many models. Unfortunately, the wiring is badly corroded so the
transformer is not repairable. Among them (there may well be others):

STR-6120
STR-6050
STR-6055
STR-6065
STR-7045
STR-7055
STR-7065
HP-188
HP-210

Anyone got a scrap unit that they'd be willing to pull the transformer
or board from and sell me?

Thanks!
Tim Schwartz
Bristol Electronics
t...@bristolnj.com

N_Cook

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Oct 27, 2015, 11:32:30 AM10/27/15

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If that Tx is showing corrossion then any ceramic resonator is probably
gone ohmic .

Rheilly Phoull

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Oct 27, 2015, 6:09:14 PM10/27/15

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"N_Cook" wrote in message news:n0o5a3$idm$1...@dont-email.me...

What does "Gone Ohmic" mean ??

Dave Platt

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Oct 27, 2015, 7:59:35 PM10/27/15

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>Hello all,
>
> I need a 1-403-290-11 detector transformer which after 35 or 40 years
>is no longer available from Sony. It was used in the tuner section of
>many models. Unfortunately, the wiring is badly corroded so the
>transformer is not repairable. Among them (there may well be others):
>
>STR-6120
>STR-6050
>STR-6055
>STR-6065
>STR-7045
>STR-7055
>STR-7065
>HP-188
>HP-210
>
> Anyone got a scrap unit that they'd be willing to pull the transformer
>or board from and sell me?

You might want to post a query on the FM-tuners group on Yahoo
(affiliated with the www.fmtunerinfo.com site). Lots of tuner
collectors and tuner-repairers hang out there, and they may be your
best chance to locate a parts unit.

From the look of the schematic of one of the models you cited, it
looks as if the Sony transformer is essentially a standard one for a
ratio detector, with a center-tapped primary and with a cap across the
full primary winding (presumably to resonate it at 10.7 MHz, adding
some amount of IF filtering). You might be able to adapt a more
common ratio-detector transformer (if you can still find one, and if
it has a center-tapped primary winding) by adding such a cap.

Unfortunately it looks as if ratio-detector transformers are pretty
much unobtanium these days, at least on the new-parts market. Opening
up and rewinding a 10.7 MHz IF transformer to add the extra winding
and the resonating cap(s) might turn out to be your only solution, if
you can't find one in a junked Sony.

M Philbrook

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Oct 27, 2015, 8:27:54 PM10/27/15

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In article <z_-dnaE0EeGYa7LL...@westnet.com.au>,
rhe...@bigslong.com says...

as in, it shows resistances via an Ohm meter?

more like, leaking DC, or leaking period..

Jamie

Dave Platt

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Oct 27, 2015, 8:52:29 PM10/27/15

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In article <MPG.3099f059a...@news.eternal-september.org>,

M Philbrook <jamie_...@charter.net> wrote:

>> If that Tx is showing corrossion then any ceramic resonator is probably
>> gone ohmic .
>>
>>
>> What does "Gone Ohmic" mean ??
>
>as in, it shows resistances via an Ohm meter?
>
>more like, leaking DC, or leaking period..

Or, has had its internal series resistance increase to unacceptable
levels; this would lower the Q of the resonant circuit, increase
losses, and make it less effective as a narrow-bandwidth filter.

Chuck

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Oct 28, 2015, 2:01:23 PM10/28/15

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I believe these are from 1972 and don't have any ceramic filters.

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jurb...@gmail.com

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Oct 28, 2015, 2:20:42 PM10/28/15

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Can you blueprint it ? I mean make a drawing showing the connections and dimensions like a mechanical drawing ? If so I can look in my boneyard. I don't have any Sonys lkike that but Marantz, Sansui, Pioneer, a few others. transformers are usually made by transformer companies. Also, the chip that drives it has an equivalent likely, finding tuners that use the equivalent might turn up the right part in a totally different unit.

jurb...@gmail.com

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Oct 28, 2015, 2:25:11 PM10/28/15

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It has two in the FM IF strip. But the OP probably has already confirmed on a scope that the IF signal is getting through. That's probably what led him to the problem.

There was an era when every one of those things was the same almost. Everything but the Revox and you do not want to see the print of one. I can't figure out how the damn thing works ! Well actualy I can but it would take time, the Revox is an extremely sophisticated unit.

Anyway, Sony might have been the first one to use ceramic filters, because 1972 does seem early for that.

Michael Black

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Oct 28, 2015, 2:54:11 PM10/28/15

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Clevite had ceramic filters in the early sixties. I've seen articles that
came out in 1964, and probably earlier.

I'm not sure how long they took to appear in products, and certainly the
early ones I read about were for 455KHz, which of course was pretty useful
so maybe that's all that got mentioned in hobby circles. Later in the
decade they did appear in Japanese products, low end shortwave receivers
and CB sets. There were mechanical filters made in Japan in that era (the
ones that now need refoaming), and they did appear in some products, but
the catalogs put them in more products than I'd expect (or rather, the
products were cheap enough to be suspect), making me wonder if someone was
mixing up mechanical filters with ceramic filters.

I have no idea of when 10.7MHz ceramic filters became common. Since FM
was wideband, their selectivity wasn't needed like they were at 455KHz, so
those might have arrived later, once the value of replacing a bunch of IF
transformers (and the need to align them flat over a wide bandwidth) was
seen as useful.

Michael

N_Cook

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Oct 28, 2015, 3:18:34 PM10/28/15

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Even 1 volt DC on a ceramic resonator is enough to induce metalisation
creep over the edge of the thinest element inside , given some time.
Being 40 years old and/or dampness/condensation can induce it also,
whether powered up or not, dissimilar metals and moisture providing the
"DC".
Easy job to remove them , well 3 pin ones anyway, and of course should
show no DVM-R reading

Phil Allison

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Oct 28, 2015, 7:42:39 PM10/28/15

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Michael Black wrote:
>
> >
> >
> Clevite had ceramic filters in the early sixties. I've seen articles that
> came out in 1964, and probably earlier.
>
> I'm not sure how long they took to appear in products, and certainly the
> early ones I read about were for 455KHz, which of course was pretty useful
> so maybe that's all that got mentioned in hobby circles. Later in the
> decade they did appear in Japanese products, low end shortwave receivers
> and CB sets.

** Murata ceramic filters for 455kHz, single and dual element, were available in the late 60s - my local parts store had them.

> I have no idea of when 10.7MHz ceramic filters became common.

** Murata 10.7MHz IF filters for broadcast FM were common in the early 70s.

.... Phil
... Phil

Tim Schwartz

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Oct 30, 2015, 7:02:13 AM10/30/15

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Gentlemen,

This receiver was stored in humid conditions, and the glue (contact
cement) that was used to hold wires in place inside the transformer
attacked the wire coating and wire.

On this particular transformer it looks like there was a 'knot' of
wires soldered and glued, possibly a factory repair when the transformer
was made.

Regards,

Tim Schwartz
Bristol Electronics
t...@bristolnj.com