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Re: Turn on Apple to preserve it?
Michael J. Mahon wrote:
(snip)
It actually says that if the power supply is disconnected from the
main board, the power supply will sense this "no load" condition and
respond by "short circuiting" its +5v output (with a "crowbar" SCR)--
because the output voltage is trying to exceed the rated voltage limit.
The unloaded condition is unusual for an Apple II power supply, but
the "clicking" mode of repeated crowbar operations should be safe.
When IBM first shipped the PC/AT the hard disk was optional.
A resistor (with a disk drive style connector) was supplied,
as the power supply couldn't run without that extra load.
I did destroy a PC style (non-IBM) power supply once
running it with no load. The usual smell of burning
phenolic compounds, and it was toast.
When forming the line-side supply capacitors, the clicking won't
even start until the voltage has been increased a few times. And
I'd worry a little about the supply straining to regulate to a
dummy load when its input voltage is well below rated levels.
But if you'd prefer to avoid crowbar mode, putting a load on the
+5 supply that does not exceed 2.5A should be OK (might be worth
checking how much current your chosen bulb draws--they tend to
have very low resistance when cold).
Yes, but a 12V bulb won't be so bad. A 12V 2A bulb will start
to get a little orange, and should stay below 2.5A at 5V.
Some day I should buy a variac, though.
-- glen