power supply problem

[Kenneth Martinez]

I'm happy to report that my Xpander is working correctly again...symptoms
were that it failed the DAC MONO test on the Service page, and there was a
waivering in the pitch of all VCOs and self-resonant VCFs, and it failed
the tuning routines...I eventually discovered that the -12V portion of the
power supply was passing an inordinate amount of ripple...thanks to all
those on synth-diy who gave suggestions - it turned out that filter cap C8
was open and so wasn't filtering at all, which is perhaps why the 7912
started to fail - replacing both of those corrected all problems.

I'm still trying to get a grasp on the benefits of switching power
supplies...Harry said transformers are smaller...my Xpander supply has one
big transformer whose output is regulated & feeds the switching circuit,
which drives a smaller transformer... and the first transformer is just as
large as what's used in a linear supply.  So - is the difference that the
big transformer in the switching supply somehow generates less heat than
the one in the linear supply?