One of the interesting things about living in modern times is that a confluence of the Internet and rapid changes in the electronics industry means that test gear that used to be astronomically priced is now super affordable. Especially if, like [Frankie Mashockie], you can do a little repair work. He picked up an HP6038A power supply for $50. We couldn’t find the original list price, but even refurbs from “professional” sources go for around $800. However, the $50 price came with a “for parts” disclaimer.
The power supply is autoranging. You usually think of that as a feature of meters. In a power supply, autoranging means the device can adjust the voltage based on load as you can see explained in the video below.
The repair had some smoky bits, and it is part 1, so we presume there will be a part 2. The end of this video was pretty hopeful, and we are anxious to see how much more might be wrong with it.
HP made a lot of power supplies that are still out there. And, of course, there are also the power supplies resident in most of our equipment to repair, too.
$2675 in 1990 was the list price…. (See http://hparchive.com/Catalogs/HP-Catalog-1990.pdf pg470)
THese are nice units, even by today’s standards. 0.01% +-3mV regulation, 0.01% +-5mA in current mode, with p-p noise the same, to 60V, with a 1ms 10% recovery. Not top of the line today, nor even quite my 66311D, but better voltage range and still respectable today.
You can also set them up as voltage following amplifiers, so you can pump a function generator output into the back of the 6038 and get a monster AWG. (It’s not great at this because it’s slow, particularly on high to low voltage transitions because it’s not a four quadrant supply, but if you have something that draws a lot of current and you need to force a waveform on it, this will work.)
You can sometimes get these for cheap with the 001 option, where they only have a blank faceplate, and then use the GPIB control along with a GUI written like the one on hackaday last week. They’re great supplies.
The quadrature encoder behind that knob fails more often than you’d expect but it’s pretty easy to replace if you can find a replacement part; they are available on ebay and shared among different power supplies. (But not, I believe, with the more common 34xx series: those use a dirt cheap one you can buy from digikey.)
I am familiar with changing the encoders. Very familiar. Surprising given HP pioneered the optical units, but …