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
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?
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.
I know it's popular to bash anything related to the government, but I don't believe the Navy was't aware of what private industry had done.
I suspect they were looking for higher reliability or something.
If your transistor radio breaks, you do without it for a day until you can get another one.
If your Walleye** missile breaks, you've wasted an entire expensive missile, and allowed the enemy to escape and do whatever harm they had planned to do. Plus a portion of everything it took to get the plane to the battle-area.
**The were also working on the Wall-eye (sp?) air-to-land missile in
1965, with a camera on gimbals in the nose of the missile, with which the pilot could aim the missile and it, with his help I think, could keep the camera aimed at the target, and the missile brain would make sure the missile was also heading for the target. When fully operational, itt was supposed to be able to enter a doorway. In Viet Nam I guess. I don't know if it ever worked then, but it was part of the development of the missiles we saw in the first Gulf War in 1990. I wish I knew the details of those 25 years.
Well, here's a little bit about it:
And it looks like the Walleye II is still operational;
Thanks for the history lesson. I worked on wave solder, "and smt" machines for years. Never really knew the history. The wave systems stilll run pretty much exactly the same way, less some preheats, and nitrogen gas here and there. I always thought it was neat that if you dropped your wrench in the solder bath, it would float on top. Loved those things.
Were any of those 'radio set mfgs' certified for 'mil spec' soldering? It's one thing to splash solder on a cheap paper based, consumer grade PC board and quite another to have it pass inspection for military applications.
No as far as I know they were only for commercial distribution - eg for people who wanted a quality transistor radio.
But it wasn't about 'splashing..' it was dipping and then the board was run by inspectors who then hand soldered any joints that even looked suspect.
My job at the time was final testing and faulty part replacement of the completed boards before they were mounted into their case. Though for a few days I was one of the dry joint inspectors.
As far as I can remember there were very few faults due to dry joints by the time the sets came to me.
But I know nothing about military specs etc so... But on a TV show last night they mentioned that the rockets with the space program would have up to 60,000 faults in a rocket I guess their specs were either not up to military standard or the military needs to do some quality control ed.
That is float soldering, not wave soldering. A much older method, and prone to quality problems. regency built two way radios that way at one time, and they rarely survived the warranty period withoutout time on the bench to clean up and resolder large areas of the board.
That's why they don't use lead free solder. Yhe US military and NASA have their own standards that take weeks to learn at an approved school. There is no way any US missle is going to leave the factory with those kinds of problems. I have built electronics for NASA and the ESA. You don't ship cold solder joints in $20,000 to $80,000 radios. I have no clue about those built down under. :)