Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!hplabs!hpfcdc!hpfcdj!myers
From: myers@hpfcdj.HP.COM (Bob Myers)
Newsgroups: sci.electronics
Subject: Re: want help with power supply
Message-ID: <11170022@hpfcdj.HP.COM>
Date: 6 Jul 89 18:05:43 GMT
References: <113785@sun.Eng.Sun.COM>
Organization: Hewlett Packard -- Fort Collins, CO
Lines: 51

>ac	hot ac
           "line"
>acc	ac common
           "common"
>gnd	earth ground
           yep - "safety" or "green wire" ground

>pf	????
           This is probably a logic output - "power fail" - indicating to
           the equipment being powered that the supply has detected the loss
           of the AC line and will be shutting itself down VERY soon (say
           about 1-10 msec from the assertion of this signal - actual time
           depends on how long the caps can keep the supply going, but around
           1-10 msec is typical.)

>on/off	???? This is NOT a switch, just a bind post

           Probably a logic input - a "remote" on/off, permitting the supply
           to be shut down/turned on via a TTL line.  If the supply does not
           function when this pin is left unconnected, try grounding it.
           (You may wish to trace it out first, to verify that it runs to
            an appropriate-looking input.)

>+s1	??
>-s1	???

           The "s" inputs are most likely for remote sensing of the output
           voltages; +/- s1 would correspond to output 1, and so forth.
           Remote sensing is used in many supplies so that the voltage being
           regulated is actually that across the load, and not that at the
           output terminals of the supply.  This eliminates potential (pardon
           the pun) problems caused by voltage drops in the wires between the
           supply and the load.  Simply hook these terminals up across the 
           load, so that the voltage to be regulated appears across the 
           terminals in the proper polarity.  Heavy wire is not required for
           this, as the current drawn by the sense terminals will be very
           small.

           Not all of the outputs will necessarily have remote sensing
           capabilities; this is typically used only on those outputs which
           are expected to have a fairly heavy load.  Outputs without
           sensing are either regulated separately, with the voltage being
           monitored at the supply terminals, or (and more typically) use
           some simple linear regulation and actually track the main output
           to some degree, as this is the only output which is actually 
           monitored by the regulation circuitry.

           Hope this helps.


Bob M.