Hi,
One thing which I have has not seen mentioned in this minimum load
discussion is the fact that an ATX PSU on its own should *not* start. You
have to link the power-on input (green wire) to 0 volts to do that. This is
what the MB does, via the stand-by +5V, a bit of logic & the "on" button. On
the PSUs I've used for non-PC applications, there was never a need to have
any load to make it work.
Regards,
Richard.be
----- Original Message -----
From: "Andy Medina" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Wednesday, September 06, 2006 6:01 AM
Subject: Re: HARDware: Minimum Needed to Run
On Tue, 5 Sep 2006, Harondel J. Sibble wrote:
He goes on to say on page 304 and 305, that some PSU's have an internal
load resistor and will startup without ANY load attached, but that most
modern PSU's require less load than above, but nonetheless require a load
for startup due to the nature of switching vs. linear power supply
design.
True, generally switching power supplies do need a minimal load (whether
that is supplied by an internal "load" resistor or by an external load) to
at least get the PS *started*.
------------------------------
<http://www.smpstech.com/mtblog/minimum_power_supply_load.html>
Minimum Power Supply Load
"I like the concluding sentence in the comment, "So, we say that a minimum
load is necessary to waken the power supply." I've never heard it put this
way, but it is often true."
------------------------------
And from the posted article:
------------------------------
<http://www.formfactors.org/developer%5Cspecs%5CATX12V_PSDG_2_2_public_br2.pdf>
3.4.3. No-load Operation
No damage or hazardous condition should occur with all the DC output
connectors disconnected from the load. The power supply may latch into the
shutdown state.
------------------------------
BTW that was a impressive switching PS article. Thanks Harondel, for
posting that url.
I imagine that most of this comes into play when testing a PS outside of
the computer case. Usually a PS attached to a mb with a processor and ram
should startup the PS. On the other hand if the PS is completely
disconnected from the mb (and any/all other items), then it's very
probable (if it does not have an internal load resistor) that it will
appear *dead*.
--
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