I got my HP 6209B working. I lucked out that this unit and the owner's manual were created with ease-of-maintenance as a requirement. Of course I had to replace the autopsied, definitely-not-a-film cap, but I figured that while I've got the patient opened up on the operating table I'd replace the other big caps before they go all RIFA on my ass. I tested the capacitance and ESR of all of the outgoing caps and also of the incoming caps as well. Those old Sprague caps looked great on the LCR meter. I was surprised that one of the outgoing caps was right on spec for capacitance and had a (slightly) lower ESR than the cap that was to replace it. That's for an aluminum electrolytic made in 1986. Hats off to HP for buying really nice caps. I also replaced the integrated power cord. I wouldn't have had to, but some rocket surgeon twisted the old one up tight before putting this unit into storage several decades ago and it had taken a set as curly as the handset cord on a Western Electric Model 500. After buttoning everything back up I cranked up the power supply to 300V / 100mA and hooked it up to my DC electronic load for a few minutes. I'm proud that I was able to get it running again. I will never be at the pro level but I am enjoying the journey.
Because the new caps have only two leads, the caps were flapping in the breeze so I tacked them down with a bit of electronics-friendly silicone. I wouldn't be able to live with myself, if, after I died, the unit failed because a cap lead broke from vibrations during shipping.
The manual has a couple of interesting items. Even though it's rated for 0-320V, "[...] the power supply can be operated floating at up to a maximum of 300 Volts off ground". Also, the procedure for setting the current in CV mode includes the following: "Short circuit output terminals, set meter switch to desired current range and adjust Current Controls for desired output current." Well, when the output is set to 300V, shorting the output terminals results in a spark and an audible "pop".
I also finished up my Topward TPS-4000 DC power supply. I bought it fully functional, but it seems that the previous owner(s) had dropped it on its face more often than they should have. I replaced the post-rectification smoothing caps (preventative maintenance), the power switch, the tracking/independent switch, and all of the binding posts. I desoldered a couple of the binding posts but eventually realized that it's easier to just cut the binding posts in two with a nice pair of side-cutters. The old binding posts for the variable outputs were yellow(+), red(-), and black(G). Inexplicably, the fixed 5V output used an alternate color scheme of red(+) and black(-). This bit me at least once when I was inattentive and hooked up a device backwards, resulting in an audible "pop" (and a flying cap case) from a small electrolytic capacitor. Additionally, I filled in the markings in the knobs with a Sharpie that I sharpened with an X-Acto. I wiped the excess ink off the knobs with a paper towel dampened with IPA. This unit is a joy to use.
Now I think that I finally have everything I need to start characterizing small signal vacuum tubes, so I'm waiting for FedEx.
The other day I dreamed up an unlikely scenario wherein I needed to automate the graphing of tube input voltages vs output voltages. I started looking around on ebay for bench multimeters that play well with sigrok and testController. I quickly found one and made an offer that was accepted. The package is now bouncing around in the back of a FedEx truck on the way to my nest, if FedEx's tracking is to be believed. Of course, yesterday their site said that the package was in a neighboring state (Oregon) and would definitely be delivered no later than 9PM, no question. I had my doubts, but kept an eye out the window. The FedEx truck drove down my street, made some deliveries, came back up the street and zoomed right past without so much as a how-do-you-do. FedEx now says that TODAY is the big day and that my package will certainly be delivered no later than 9PM. Hmph.
Off-topic, on-topic:
This stuff is quite good, except that it will make you sick or poor or fat. Try it with ice and cream and vodka, or with fancy vanilla-bean ice cream and self-pity.
https://www.godivaliqueurs.com/Oh, I think I hear FedEx. Gotta go!
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