Jeff Liebermann wrote:

On Tue, 15 Dec 2015 15:49:13 -0600, Jon Elson
wrote:

Jeff Liebermann wrote:

3. Things go better if you have a schematic, gallon of coffee, a
working unit to compare, and a parts unit to cannibalize.

Oh wow! This one is up there with Murphy's law!

And, unless you are the manufacturer of said device, much of the above
will never be available.

Gallons of coffee are available at your local supermarket.

I know where to find coffee, although I don't drink it.


I practice what I preach. If really want something to work, I buy 3
of them, and cannibalize one or two for parts to make one of them
work. I also buy or download the manuals:
http://802.11junk.com/jeffl/pics/home/slides/BL-shop5.html
Notice that there are three HP8620C sweep generators, and three
SSI/Wavetek 3000b service monitors in the photo.

Manuals for test gear are usually available. But, for a lot of consumer
gear, automotive modules and industrial gear, they may NOT be! That can be
a real headache.

Old CNC control gear used to have fabulous manuals, with a theory manual
three times as big as the schematics.

But, on later gear, you were lucky to get drawings of the cables, some
configuration charts, and that was ALL that was ever allowed outside the
factory. So, you had to reverse engineer how a lot of stuff worked to
figure out what was wrong with it.

A woking unit to compare to is REALLY a huge help, when available.

Jon