On Sat, 11 Mar 2017 20:34:47 -0500, Ralph Mowery
wrote:

In article ,
says...



Now that I know what the initials mean, I know what these are. I have
seen them. As far as I'm concerned, they are the devices which cant not
be repaired, unless the whole boards are replaced. Yes, i am sure they
can be repaired, but it wont be me working on them. Poor eyesite is just
part of the reason. Thats why I prefer the old tube stuff to work on, or
at least the early transistorized stuff on single layer boards, which
contain parts that can be touched without using a tweezers....

For me, IC chips and SMDs took the fun out of electronics as a hobby...
(Not that they are bad, but they are not for the home workshop, they are
made for robots in factories that create them, and people who have very
expensive test gear to trace them). I still recall trying to unsolder
some IC chips, and ruining them every time. Then spending days or weeks
trying to locate replacement parts, because they are factory numbers
that cant just simply be purchased.


I am 67 and just started working with the SMD about 2 years ago. If
your hands do not shake too much it is easy if you have the right tools.
For the hobby people like me that does not want to spend too much, it
takes about 300 to 350 to really get the right equipment. A good
microscope can be bought for about $ 190. A hot air and small soldering
iron combination is about $ 60. Then a few tweezers, very fine
solder,liquid solder, liquid flux and some kapton tape round up most of
the other items you need. Get some old computer boards and practice for
several days and it will be easy. Be sure to look on youtube for some
videos to see how the pros do it. They make it look very easy.


One easy way to replace the ICs is to cut the legs from the plastic case
and remove them a pin at a time. Don't try to save them.

The odd ball factory numbers are something else. There should be some
kind of rule they can not use house numbered parts unless it is
especially made for that piece of equipment and not used by anyother
company.
Some companies even sanded off all the numbers on the parts.

The old tube stuff was made to be repaired. You'd unplug a tube and
stick it in a tester. If it was not the tubes, you'd begin checking the
passive parts.

With ICs, you cant unplug them or test them. They DO make sockets for
them, but they are never used on consumer products, and if they could be
unplugged, there are no testers, at least not a general purpose tester
for all ICs. I suppose companies have testers for specific ICs that they
use. Cutting the leads on the ICs is a good idea if you know they need
to be replaced, but much of the time you want to remove them to test
them (as best as possible) out of the circuit.

At least single transistors could be unsoldered and tested. When I used
them for some projects that I built, I always put them in sockets.

Things just are not made to be repaired these days. And like you said,
the part numbers are often "house numbers", which makes it impossible to
fix the stuff. I guess thats why computers are made wih boards that are
just unplugged and replaced. The boards themselves are the components,
but often times the boards cost more than the whole device.