Re: Evolution of electronic circuit construction technology
"I think it worth pointing out that my personal experience of how electronic circuits are constructed shows a steady movement away from putting chips in sockets, and towards soldering them directly to the PCB. As far as I know, much of the electronic service industry works on the basis of swapping out complete boards, rather than repairing at component level."
The big reason for putting chips in sockets was cost and upgrading. Rather than putting the expensive chips on the board right away, it made more sense to test the board to make sure it worked properly and add those chips later. There are also easier ways now to program firmware in situ rather than putting an EPROM in a programmer.
Board level repairs are useful in a field service environment where getting a piece of equipment back up and running as quickly as possible is the most important thing. It can be more efficient to have a dedicated testing rig at a depot that can pinpoint a component that has failed or narrow down possibilities much faster. It's also hard to drag around a whole lab worth of equipment in the boot of a car.
Some companies are so paranoid that they think providing schematics is going to divulge trade secrets. This is lawyer-think since reverse engineering electronics isn't that hard when you are set up for it. Companies are out there that do nothing but and can x-ray chips to figure out what they are or even take them apart to examine under an electron microscope. I remember some classes I had where we were given a black box and had to figure out what was inside given some basic parameters.
My first job after getting my degree was working at a company that was a contract repair station for musical instrument/sound system products. I'd worked previously as a roadie and for various local and national lighting and sound companies and one thing I noticed was that certain gear was very common. It wasn't because it was the best. It was good enough and could be repaired. Getting a schematic and parts from the OEM was no problem. They'd even overnight stuff to a hotel and worry about billing later if they knew you or the company you work for. So much kit is so similar that trying to keep something secret was useless. I thought at one point that I'd build my own graphic EQ as a project. After totting up the costs to buy the parts, I found it far better to buy one new. If I wanted to save money, I could get one second hand or try to find a broken one I could fix. The upshot is that gear that had the best support was the most prevalent. Since it was used in so many installations/rigs, it was a known quantity and sold well just through momentum.
Biting the hand that feeds IT
