I just built a power supply that provides +6V, +5V, +3V, and -6V, using
several linear regulators, 2 of which are 7806 and 7906 (for the +6 and
-6). Sometimes it's fine, but sometimes when I turn it on the +6 supply
doesn't appear, and hovers around -0.8V instead.

I vaguely remember reading about this problem somewhere in the dim and
distant past, but I can't for the life of me remember the trick to fix
it. I tried putting asymmetric loads on the outputs, but that doesn't
seem to do it. Can anyone shed some light on this for me?

Dave Johnson