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From: RJO on 23 Apr 2010 21:56
I've had a great Sony SW7600 portable shortwave/AM/FM radio for years
and it has worked very well. It's probably been on for more than ten
thousand hours overall. This is the model:

http://www.universal-radio.com/catalog/portable/icfsw7600.html

A few months ago it started giving only loud static when turned on,
even when tuned to a standard station. If I left it on for an hour or
two it would usually snap back to normal operation and the station
would come in clear again. But now it's gotten to the point that it
never comes back: only loud static when turned on, and for all the
time it is left on. You can faintly detect the signal in the
background in most cases, but it's drowned out by the static. (These
are strong stations I've listened to for a long time; something
changed in the radio, not the environment.)

My mechanical intuition tells me the problem is simple, but I know
nothing about electronics. Is anyone familiar with these old workhorse
portables? If the repair is more complex than whacking it with a
hammer I probably couldn't do it myself, but perhaps it would be worth
sending it out for repair? Or should I toss it in the wastebasket?
Sell it for parts on eBay?

Many thanks.

Bob
From: nesesu on 23 Apr 2010 22:40
On Apr 23, 6:56 pm, RJO <rjohara....(a)gmail.com> wrote:
> I've had a great Sony SW7600 portable shortwave/AM/FM radio for years
> and it has worked very well. It's probably been on for more than ten
> thousand hours overall. This is the model:
>
> http://www.universal-radio.com/catalog/portable/icfsw7600.html
>
> A few months ago it started giving only loud static when turned on,
> even when tuned to a standard station. If I left it on for an hour or
> two it would usually snap back to normal operation and the station
> would come in clear again. But now it's gotten to the point that it
> never comes back: only loud static when turned on, and for all the
> time it is left on. You can faintly detect the signal in the
> background in most cases, but it's drowned out by the static. (These
> are strong stations I've listened to for a long time; something
> changed in the radio, not the environment.)
>
> My mechanical intuition tells me the problem is simple, but I know
> nothing about electronics. Is anyone familiar with these old workhorse
> portables? If the repair is more complex than whacking it with a
> hammer I probably couldn't do it myself, but perhaps it would be worth
> sending it out for repair? Or should I toss it in the wastebasket?
> Sell it for parts on eBay?
>
> Many thanks.
>
> Bob

From your description, it could be a failure of the solder. Sony has
been notorious for solder problems depending on the factory and
product as well as era it was made. If you can open the set and
operate it, then you could gently probe the components with a thin
insulated probe to see if a bit of pressure in an area restores
operation. One problem doing this is that if the defective joint is
actually moved, it can restore operation for hours, days or months
before it re-appears, If prodding does restore operation, then it is
often effective to simply resolder every joint that looks even
slightly suspect with a suitable small iron and top quality rosin
solder. If the radio is not RoHS compliant, then use tin-lead 63-37
solder.
If prodding around has no effect, the problem might be a defective
semi-conductor. You might also consider replacing all the electrolytic
caps since they are prone to going high ESR with age, again depending
on the date and make.

Neil S.
From: N_Cook on 24 Apr 2010 12:24
RJO <rjohara.net(a)gmail.com> wrote in message
news:cc198b01-beb1-49dd-996f-ed9ce735793c(a)z7g2000yqb.googlegroups.com...
> I've had a great Sony SW7600 portable shortwave/AM/FM radio for years
> and it has worked very well. It's probably been on for more than ten
> thousand hours overall. This is the model:
>
> http://www.universal-radio.com/catalog/portable/icfsw7600.html
>
> A few months ago it started giving only loud static when turned on,
> even when tuned to a standard station. If I left it on for an hour or
> two it would usually snap back to normal operation and the station
> would come in clear again. But now it's gotten to the point that it
> never comes back: only loud static when turned on, and for all the
> time it is left on. You can faintly detect the signal in the
> background in most cases, but it's drowned out by the static. (These
> are strong stations I've listened to for a long time; something
> changed in the radio, not the environment.)
>
> My mechanical intuition tells me the problem is simple, but I know
> nothing about electronics. Is anyone familiar with these old workhorse
> portables? If the repair is more complex than whacking it with a
> hammer I probably couldn't do it myself, but perhaps it would be worth
> sending it out for repair? Or should I toss it in the wastebasket?
> Sell it for parts on eBay?
>
> Many thanks.
>
> Bob

What voltage source keeps the stations in memory ?


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://diverse.4mg.com/index.htm


From: RJO on 28 Apr 2010 21:52
Thanks very much for these detailed insights. Perhaps if I get
adventurous (I'm not an electronics person) I'll open the case and
poke around with a toothpick to see if it changes anything. It may
well be from my amateur position that this will turn out to be more
expensive to repair than would be worth it. It has been a great radio
though, and if anyone gets the chance to acquire one in good condition
they should take it. If the toothpick treatment doesn't work maybe
someone will want it for parts, since 90% of it is still in good
shape.

Bob

On Apr 23, 10:40 pm, nesesu <neil_sutcli...(a)telus.net> wrote:

> From your description, it could be a failure of the solder. Sony has
> been notorious for solder problems depending on the factory and
> product as well as era it was made. If you can open the set and
> operate it, then you could gently probe the components with a thin
> insulated probe to see if a bit of pressure in an area restores
> operation. One problem doing this is that if the defective joint is
> actually moved, it can restore operation for hours, days or months
> before it re-appears, If prodding does restore operation, then it is
> often effective to simply resolder every joint that looks even
> slightly suspect with a suitable small iron and top quality rosin
> solder. If the radio is not RoHS compliant, then use tin-lead 63-37
> solder.
> If prodding around has no effect, the problem might be a defective
> semi-conductor. You might also consider replacing all the electrolytic
> caps since they are prone to going high ESR with age, again depending
> on the date and make.
>
> Neil S.

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