On 3/8/2016 11:48 AM, Cursitor Doom wrote:

Well, I've replaced all the flaking capacitors and still no improvement.
A number of people have been suggesting I remove the two resonant caps
(the 30n ones) from the primary circuit and test them. I didn't have any
expectation that this would achieve anything since they tested good in-
circuit, but as we're running out of ideas now I did remove them this
afternoon and they both tested at 31nF a piece and no signs of any
physical damage. I then subbed a couple of common-or-garden mylars of the
same value in their places and re-swept for changes in resonance. Result
was no change in resonance - but a slightly better Q(!!) Also checked the
two 10Meg resistors whilst I was at it and they were fine, too. So I can
only think of making up Dimitrij's winding tester and looking for signs
of any turns shorting in the main transformer.
I'm coming to the end of the amount of time I'm prepared to spend on this
psu as it stands. I'm more and more tempted to mothball the key parts of
it til next year then rebuild it as a conventional non-res converter to a
fresh design. TBH, I'm not prepared to still be testing this thing after
the end of this week, so if anyone has any last-ditch ideas, now's the
time to toss 'em into the mix. Speak now or forever hold your peace.
Thanks, all.


I have no idea what you now consider to be wrong with the PSU. Apart
from a resistor that in your opinion runs too hot even though its well
within its rating I seem to recall amidst your ramblings that the
voltage rails are correct?

It seems to me that the only fault was the diode which was pretty
obvious from the beginning. (Always check for previous repairs).

You persist in not using the correct manual, refuse to test it with an
appropriate load and won't put it in the scope to see if the scope
actually functions.

If you just want to discuss switching supply design go buy some control
chips or an evaluation kit and build some.