On 07.03.2016 20:21, Dimitrij Klingbeil wrote:
On 07.03.2016 19:08, Cursitor Doom wrote:

I've just noticed that towards the bottom of (true) page 106, it
states the following:-

"The oscillator frequency is approximately 25kHz, determined by
network C1811, R1823 and is adjustable by means of R1824." ...

And before anyone suggests it: I've frequency swept the primary
circuit just in case there's a second resonance peak at around
25kHz and there isn't one.
...
... Also, to avoid unforeseen measurement errors, can you do that
out of circuit? Just the transformer and the capacitor(s) on the
primary.

P.P.S. If you decide to sweep the LC part in circuit instead of out of
circuit (because the transformer is difficult to solder out etc...), you
can use a small voltage source (a 9 V block battery) connected to the
power supply's "AC" input. This will precharge the circuit enough to get
the parasitics down. It won't start the power supply controller, but it
will reverse-bias various diodes and also the base-collector junction of
the main switching transistor. That will make these semiconductor parts
non-conducting (at small signal levels) and prevent them from rectifying
the test signal from your sweep generator, and messing it up in various
ways through leakage paths. It's an easier alternative to removing the
switching transistor from the circuit.

Dimitrij