Hi Max,
Well, I didn't say that the load MUST be distributed. For me reasons to do so were that I could use available 5 W and 10 W resistors and that I wasn't always sure about the maximum current an output could deliver. Your 10 W resistor will survive start attempts, but when an error has to be detected which tends to occur after several minutes then you have a problem.
I am really surprised that about 11 W was sufficient. IIRC in a 7904 the HV circuits are less easily to disconnect so maybe these formed a load also. At this moment I don't remember all the details, but I think 11 W would not even be enough to maintain the 7.5 zener voltage inside th IC. Anyway, over 50 W was my experience.
Albert
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To Albert:
I really don't know how a dummy load must be connected to raw outputs! Some
people told me to load +17V was sufficient, some others the +108, now you and
others say that the load MUST be distributed across the raw outputs! I'm
really confused now...
And yes, I've disconnected the supply to HV unit obviously... since the SMPS
block sits on my workbench, alone.
Some times ago (several months ago I suppose), a friend of mine fixed a 7904
SMPS; he told me that as a load he had connected a 20 ohm resistor on the +15
(regulated output) and nothing else and the smps worked ...
