...And if you don't have a schematic, you ring out the connections and draw
your own...
Given the number of times I've done that, I half-feel like mentioning
a grandmother
and sucking eggs ;-)
More seriously, to draw out a useful schematic -- not just one that
shows what is
connected to what, but also groups related sections together, also
requres a good
understanding of the device, of what is likely to be going on, etc. In
other words that
brain comes in handy...
-tony