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From: stratus46 on 10 Jan 2010 00:59
On Jan 9, 5:38 pm, mm <NOPSAMmm2...(a)bigfoot.com> wrote:
> On Sat, 9 Jan 2010 17:00:31 -0800 (PST), Eli Luong
>
> <elilu...(a)gmail.com> wrote:
> >I have an old stereo system that I'd like to keep using and I'd like
> >to try to add a line-in jack for plugging in an MP3 player or
> >connecting audio from a computer. I found the service repair manual,
> >and it looks like the cassette, tuner, and CD all go to this one IC -
> >LC75392 (http://datasheetcatalog.com/datasheets_pdf/L/C/7/5/LC75392.shtml).
> >Can I just solder leads from a stereo jack to the
> >appropriate pins onto the IC, and the ground to the ground?
>
> I don't know the elctronics, but I'd solder to the copper trace
fairly
> far from the IC to avoid overheating the IC.  The original
soldering
> was done by a machine, or a guy who did it all day and got very
good
> at it.
>
> (When I was a summer employee of the US Naval Avionics facility in
> Indianapolis in 1965, they were working on a way to solder all the
> connections on a circuit board at one time.  They had a couple
> "machines" each with river of solder a foot wide that they would
> barely dip the whole circuit board into.  They'd been working on this
> for months or more, plus the three months I was there.  I walked by
> every day but didn't work in that department. I think my boss said it
> was hard to keep the surface of river flat.
>
> Who did figure out how to do this, and do any of you know when it
> happened?
>
> Do any of you know what the process is called?
>
> Thanks.
>
>
> >- Eli


It's actually pretty hard to ruin an IC with a soldering iron - unless
it's a Bernz-O-Matic.

G²
From: Eli Luong on 10 Jan 2010 01:13
On Jan 9, 9:57 pm, stratu...(a)yahoo.com wrote:
> On Jan 9, 5:00 pm, Eli Luong <elilu...(a)gmail.com> wrote:
>
> > I have an old stereo system that I'd like to keep using and I'd like
> > to try to add a line-in jack for plugging in an MP3 player or
> > connecting audio from a computer. I found the service repair manual,
> > and it looks like the cassette, tuner, and CD all go to this one IC -
> > LC75392 (http://datasheetcatalog.com/datasheets_pdf/L/C/7/5/
> > LC75392.shtml). Can I just solder leads from a stereo jack to the
> > appropriate pins onto the IC, and the ground to the ground?
>
> > - Eli
>
> OK, that's fine but how do you control the chip to select the new
> input? Or are you giving up one of the existing inputs?
>
> G²

I was thinking why can't I just piggyback on one of the inputs. eg if
I connect it to the cassette tape input, then I won't use the tape and
the aux input at the same time?
From: mm on 10 Jan 2010 01:46
On Sat, 9 Jan 2010 21:59:22 -0800 (PST), stratus46(a)yahoo.com wrote:

>On Jan 9, 5:38�pm, mm <NOPSAMmm2...(a)bigfoot.com> wrote:
>> On Sat, 9 Jan 2010 17:00:31 -0800 (PST), Eli Luong
>>
>> <elilu...(a)gmail.com> wrote:
>> >I have an old stereo system that I'd like to keep using and I'd like
>> >to try to add a line-in jack for plugging in an MP3 player or
>> >connecting audio from a computer. I found the service repair manual,
>> >and it looks like the cassette, tuner, and CD all go to this one IC -
>> >LC75392 (http://datasheetcatalog.com/datasheets_pdf/L/C/7/5/LC75392.shtml).
>> >Can I just solder leads from a stereo jack to the
>> >appropriate pins onto the IC, and the ground to the ground?
>>
> > I don't know the elctronics, but I'd solder to the copper trace
>fairly
> > far from the IC to avoid overheating the IC. �The original
>soldering
> > was done by a machine, or a guy who did it all day and got very
>good
> > at it.
>>
>> (When I was a summer employee of the US Naval Avionics facility in
>> Indianapolis in 1965, they were working on a way to solder all the
>> connections on a circuit board at one time. �They had a couple
>> "machines" each with river of solder a foot wide that they would
>> barely dip the whole circuit board into. �They'd been working on this
>> for months or more, plus the three months I was there. �I walked by
>> every day but didn't work in that department. I think my boss said it
>> was hard to keep the surface of river flat.
>>
>> Who did figure out how to do this, and do any of you know when it
>> happened?
>>
>> Do any of you know what the process is called?
>>
>> Thanks.
>>
>>
>> >- Eli
>
>
>It's actually pretty hard to ruin an IC with a soldering iron - unless
>it's a Bernz-O-Matic.

I'm a marine. The difficult we do immediately. The impossible takes
a little longer.

>G�

From: Eli Luong on 10 Jan 2010 03:06
On Jan 9, 9:57 pm, stratu...(a)yahoo.com wrote:
> On Jan 9, 5:00 pm, Eli Luong <elilu...(a)gmail.com> wrote:
>
> > I have an old stereo system that I'd like to keep using and I'd like
> > to try to add a line-in jack for plugging in an MP3 player or
> > connecting audio from a computer. I found the service repair manual,
> > and it looks like the cassette, tuner, and CD all go to this one IC -
> > LC75392 (http://datasheetcatalog.com/datasheets_pdf/L/C/7/5/
> > LC75392.shtml). Can I just solder leads from a stereo jack to the
> > appropriate pins onto the IC, and the ground to the ground?
>
> > - Eli
>
> OK, that's fine but how do you control the chip to select the new
> input? Or are you giving up one of the existing inputs?
>
> G²

I found that each cassette player connects to a 3-pin or 6-pin
(recording side) plug, similar to a 3-pin CPU fan socket. So I'm going
to take the 3-pin and see if I can wire it to a 1/8" stereo jack.
From: David on 10 Jan 2010 17:39
In article <afbik51666ll913td721atop30jggrcb9s(a)4ax.com>,
mm <NOPSAMmm2005(a)bigfoot.com> wrote:

>
> (When I was a summer employee of the US Naval Avionics facility in
> Indianapolis in 1965, they were working on a way to solder all the
> connections on a circuit board at one time. They had a couple
> "machines" each with river of solder a foot wide that they would
> barely dip the whole circuit board into. They'd been working on this
> for months or more, plus the three months I was there. I walked by
> every day but didn't work in that department. I think my boss said it
> was hard to keep the surface of river flat.
>
> Who did figure out how to do this, and do any of you know when it
> happened?
>
> Do any of you know what the process is called?

This is how Kriesler Australia soldered components to PCBs for their
transister radios around 1960 - 64.

The PCBs were on a sort of travelling frame which first took the board
over a rosin spray then into the solder bath - the height was such that
only the lower (etched) side of the board dipped into the molten solder.

After the solder bath the board went to a production line where first it
was checked for dry joints, then aligned and tested for function.

It was a proven process with thousand of sets made this way

If only the Navy had thought to ask any of the radio set mfgs they could
have saved themselves a lot of work, as I presume it wasn't only
Kriesler that used this method.

David
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