[Test-Equipment] HP power cords

[Barry]

 On Mon 05/04/10 10:02 PM , "Eric Lemmon" wb6fly at verizon.net sent:
> More info:  I have two HP instruments that use the old-style oval
> detachablepower cord- a Model 680 chart recorder, and a Model 204B audio
> oscillator.Both of these instruments have isolated transformer primary windings
> thatcan be switch-selected for 120 or 240 VAC.  To the best of my
> knowledge,this wiring is typical of ALL test equipment made by HP that has the
> ovalpower inlet.  It is irrelevant which outside contact of the power cord
> ishot and which is neutral.  The only thing that matters is that the
> centercontact on any mating cord is chassis ground.  Therefore, the Volex
> cordstocked by Allied Electronics is suitable. 
> 
> I just checked the Allied stock listing, and I see that seven of those
> cordshave already been snapped up since this thread began.  He who
> hesitates...
> 73, Eric Lemmon WB6FLY

I just looked at the schematic for a204C (couldn't find the 204B version).  If the B is like the C, then it shouldn't matter.  There is no power switch or fuse in the unit.

In the 608 (and many, many other pieces of equipment), there is a fuse and a power switch and the hot side should go to this side.  Functionally, it doesn't matter, but for safety's sake, it does matter.  When the fuse blows (or you have the power switch off), you don't want the hot side to still be feeding something else inside the unit.

Barry - N4BUQ