William Sommerwerck wrote:

"Michael A. Terrell" wrote in message
...

Shotgunning is the true mark of a very poor tech. They don't
want to learn why things fail, or what parts are actually needed.

Might I respectfully semi-disagree?

I have always wanted to understand why something wasn't working correctly
before I fixed it. But as products have become more complex and harder to
troubleshoot, it seems increasingly necessary to, on some occasions, shotgun.
I don't like it, but if you're running a repair business, you have to get the
item out the door to stay in business.

If it's of any interest, I have never had a callback on anything I've
repaired. But that was in the days when virtually all electronics was composed
of discrete components you could unsolder and test, if need be.


William, the more you actually find the problem and repair what's
needed, the easier and faster it is to do on future jobs. You develop
an understanding for what kinds of parts are the highest failures, and
use logic to narrow down the problem. For instance, surface mount
ceramic resistors and capacitors have a low failure rate, but the
electrolytics have a high failure rate by comparison? Would you shotgun
a couple hundred chip caps, just in case? Would you replace a dozen
ICs, just in case?

The more parts you change on a modern surface mount board, the higher
the chances of destroying the board. It was simpler on tube radios, and
early discrete solid state designs, but it takes a lot of time and
expense to shotgun VLSI and ASIC ICs on a board.

Logical troubleshooting was the method I was taught in the mid '60s,
and after a few years on the bench I was the most productive tech.
Also, the repair costs were lower because I didn't replace as many
parts, nd the customer didn't have to wait for custom parts to be
ordered from the OEM, 'just in case'.