I was given some input (Thank you Robert!) on the motor capacitor before video release and I am currently on the side of reforming not being applicable. I've written some more detailed information about them on Caps Wiki here: https://caps.wiki/wiki/Capacitor_Types#Metallized_Polymer but in short the "Self-healing" process mentioned in the data sheets for the capacitors is not in any way related to how Electrolytic and Tantalum capacitors reform. It is a destructive process that eliminates parts of the parallel plates that have weak dialectric. With that information now I would say the reforming process is not useful and may even be detrimental to the intended self-healing of these capacitors.

The transformer is a ferro-resonant type, they partially regulate the output. The cap is part of its resonant circuit. Those caps rarely fail and typically open rather than short. If the capacitance value is within tolerance, I would consider it fine to operate. As you have noted, the "self heal" property is completely different than electolytics. If the self heal function has occurred a lot, the value will be reduced as the plate surface area becomes reduced.

The urge to put a grille on that finger-chopping fan...

9:40.
The capacitor is used with the power transformer in a special way. The transformer has an air gap and an extra winding. The air gap can cause the transformer to go into saturation early. If the line voltage is higher than normal the magnetic flux is "lost" in the air gap in an attempt at AC voltage regulation. The capacitor is hooked up to the extra winding. Due to the current phase induced it will also help or hinder the air gap saturation to help with AC regulation under various loads. The transformer is called a voltage regulating transformer and many can keep the output within 10% of regulation of the line voltage at a range of output currents. They tried to partially regulate the AC voltage on the secondary to take some load off of the DC regulators. If the capacitor is bad make sure you replace it with the exact same capacitance, even if you have to wire a few in parallel to get within the tolerance specified on the original capacitor. The transformers never act like the math tells you they should so the first one had to be bench tested, modified, and otherwise messed with before you get one that works as needed. With one working transformer you can use the same measurements (windings, wire spacing, air gap size, capacitor rating, etc) to make working copies. The transformer in a microwave oven is made in a similar way.
Edit: it's a motor run capacitor, not a motor start capacitor.

Yeah, those motor caps are a different kind of beast. I vote leave it alone until it needs replacing.

I don't undestand a thing of this device, but it's nice to see you working

16:18 Thanks... for reminding that I'm old. I was born in 1977 and 2000 feels like it was yesterday when we (all the IT geeks of the time) watched and waited world to crash on Jan 1st 2000 00:00 - and got disappointment when nothing happened... :D

That run capacitor you were wondering about, if they are like the run cap's in hvac then you just need to test if its capacity is within tolerance and if it is then it should just be good.  Any hvac place should have a tester to check it.
Don't ignore it though, if it is used as a run cap for a motor then it can damage the motor if it isn't up to spec anymore.  Or the motor could be running at a slightly wrong speed if it is part of the floppy drive motor circuit's.

I believe „Self-Healing“ in terms of Motor caps (both Start and Run) refers to their ability to heal from short-circuits, similar to how the infamous Rifa-caps are supposed to self-heal.
If you have a short somewhere, the plating on the paper burns away locally, without the cap itself failing catastrophically. It will continue to work, though at a slightly lower capacitance.
I would describe this to be something completely different than „reforming“, where you are regenerating the layers chemically to recover capacitance that was lost due to the cap „sitting idle“ for decades.

For Data General, unlike HP and IBM, easy serviceability apparently wasn't a big priority.

Love the channel, love the videos. Sometimes if I close my eyes and just listen, I can hear Kermit the frog talking. Anyone else?

Seeing that single-sided cleanign disc reminded me of one of a recurring argument I had with one of my early schoolmates' about how to handle floppy discs while we were still friends.
(for unexplained reasons in the 90's) a local source of discount floppy discs had the usual openings cut open with perforations to tear out for single-sided or multi-head use on the other three sides (with the felt/slider material in the way).  (At the time I presumed it was a messy workaround to needing to cover/uncover the write protection notch ... in situations where using the cut-off edge of an envelope was 'inappropriate'.)

(his late great-uncle? and grandfather) taught him to use a computer exclusively with these discs on some hombrew machine, and instructed him to always hold the discs by "the side with 'both finger holes' so that he doesn't touch the round part".  So he'd always damage the discs while insisting that "the side doesn't matter" and "the 'shiny' [magnetic-media] part isn't round, it's flat."  It did not help that whenever my parents let him 'borrow' my games w/ to appologise for my upsetting him about this; he'd 'lose' the games I'd saved up to buy too ,and/or scream that I'd ruined them by flattening out the creases/crinkles he put into the center ring (as I'd been taught to).

Until literally seeing your single-sided cleaning disc w/ perforated jacket, it never occured to me that he could have had learned on single sided media with the perforations under the label side(s) intact; also explaining why he thought nothing strange about the normal/common label on the end going deepest into the drives. ( _And_ was the only schoolmate that didn't complain when I'd run my labels/addendums down the entire side of my discs. )

Thermal camera inspection is such a powerful tool. I remember one place I worked developing power supplies, we would use the thermal camera and the actual trace leading to a fault would light up like a scifi diagnostic thingy. it was great. I still use thermal cameras for debuggering to this day even though I work with instrumentation signals now.

i'm enjoying this data general series, i didn't know much about minicomputers until you and usagi were making videos about them and now i'm curious about the old paradigm of big computers and terminals. so good job!

The HVAC guys are complaining about a lot of junk motor caps these days. If you go that route, make sure to get a top-tier cap directly from an industrial supplier.

Those capacitors are in arcade cabinets and they always change them out from the 70s and 80s arcade games because they are bad or going bad.

Love your enthusiasm on this old gear! I miss when I did...

From my memory, to boot the floppy or cartridge disk you need to enter 100033L (or possibly just 33L - it was a long time ago now!) at the ! prompt. The 33 signifies the device code of the drive so can be typically 33 or 27 for example. The code wheels on the drives are the unit codes which must be unique and unit 0 for the boot drive. You will only be able to boot a floppy (or the cartridge disk) if it has the RDOS operating system on it.

Mmmmmm, Data General goodness.  This is fine work, Shelby, even if it didn't go completely as you intended

Darn those caps are HUGE but to be fair, about par for the course of tech compared to now lol great video Shelby!