APC's baby UPS from 1996 - Back-UPS 200

[@eeroa.sarlin2424]

if you have a peak reading digital multimeter, the peak hold function would reveal the magnitude of the pulse.

[@themaritimegirl]

Good idea - I have such a multimeter, although it only samples once per second. But after several dozen switches, the highest reading I got was 125V, so maybe it's not as bad as I thought.

[@FFcossag]

Wow, I never thought I'd find another vintage APC nerd! Nice find, I run a 300 VA and a 650 VA version of these for my workstations to this day. Beautiful units, and they have the lowest idle power consumption of any UPS I've ever seen. Some notes on them: The "surge" is caused by the UPS pushing out a couple of cycles of very high duty cycle square wave to start the transformer reliably. If you don't do that, the time it takes to start the transformer can cause a long brownout during transfer. Since these only have "voltage" regulation by varying the width of the square wave pulse coming out of them, it's completely harmless to switching power supplies. The peak voltage (i.e, the only thing a switching power supply cares about) remains constant and is fixed to the battery voltage by the transformer's winding ratio. This also means that it's impossible for it to "surge" and damage its loads as long as they're switching power supplies. Even if you adjust it to its absolute maximum "output voltage", all you're doing is making it output a pure square wave, and the rectified voltage inside the load barely changes. The little transformer is the battery charger. It's a simple 60 Hz transformer that's rectified and stabilised by the little heatsinked linear regulator at the side of the board. You should also be careful running things like Kill-A-Watts off of modified sine wave inverters. They often contain capacitive dropper power supplies which are NOT compatible with modified sine wave inverters since they pass more current at higher frequency. If you have a ton of high frequency harmonics in your mains, the power supply will pass WAY too much power into your device and it's liable to let out the magic smoke. I learned this the hard way before I knew how that works ;)

[@themaritimegirl]

I've watched many of your videos and loved them. Thank you for the information!

[@FFcossag]

@@themaritimegirl Oh, that's a surprise. My channel is so obscure. But thanks!

[@kiwatech]

i remember those, back then in the late 90s, early 2000s, they were used on the "main" computer (the one that had a modem) on the school computer rooms, kids constantly shut them down lol

[@dysfunctionalwombat]

What a nice, high quality unit. Thanks for making such a detailed video on this, I've been interested in these for a while after seeing an APC advertisement pairing this with a Macintosh, so it's great to see a detailed video on one. I'd love to get my hands on one myself, maybe at some point I will to pair with one of my vintage systems. Preferably a higher wattage unit. Also great too see more telephone equipment, I'd love to see more videos on such. I still have my Norstars but I've graduated to a BCM which has been an interesting experience

[@DanburyDK]

Oh wow neat!! I had one of these. Or maybe the 250🧐 and I used it on my router and cable modem years ago 😏

[@GeorgeGraves]

The amount of circuritry they put in (some) of these things is insane. I have one that has to have 300 components on the PCB. No clue why. It's crazy. Also surprised more people didn't grab these and make car power inverters out of them back in the 2000's. Of course there was a real dip in DIY culture back then.

[@kyoudaiken]

I like these devices, though in Europe we literally never ever have power outages due to our mesh power grid design. There are exceptions of course, but I'm living 10 years in this apartment now and I only had one planned maintenance outage once. No other power outages. But I still find these devices very interesting from the technical point of view, specifically how they switch to battery power using their inverter. The smart UPS try to minimize the glitch when switching over from one state to the other, and they synchronize the oscillator to the phase the mains was last in when it dropped, minimizing the effects of voltages adding up.

[@themaritimegirl]

I don't know which country in Europe you live in, but I know some countries there have significant portions of their distribution network buried underground, which is also a huge factor. In North America everything is strung on poles, and weather is the #1 cause of power outages.

[@kyoudaiken]

@@themaritimegirl Yeah here in Germany it is mostly underground, except the huge poles. Weather can still cause outages, but the mesh system makes it so that they can switch circuits around to maintain service.

[@foxhazhax4845]

I have one of these. I replace the AGM battery every 2 years, it's saved my butt about 6 times now

[@rootvalley2]

I get about 5 years out my batteries sometimes 8

[@eDoc2020]

I have one of the larger versions (maybe 450) made in 1999. If you try starting from battery it just beeps continually but pressing the alarm silence button makes it start up. Obviously the mini version doesn't have the test/silence controls (or the "serial" port) but I am curious if the mini ones still have the circuitry for these functions.

[@rs12official]

I saw an even smaller UPS at a thrift store the other day. It was maybe around 7-8” tall and 4-5” wide on all sides. It had four outlets on the top, but I think only two were on battery. I think it was rated for 250 watts or so on battery and 9A on grid power. I didn’t end up buying it since they wanted $29.50 for it and they would only give me a 10% discount.

[@jorno1994]

the small transformer may actually be a common mode choke

[@theaustralianconundrum]

I remember them! Good grief. Thank heavens for modern inverter generators!

[@themaritimegirl]

UPSs and generators serve different purposes though :)

[@theaustralianconundrum]

@@themaritimegirl Oops! I'm Australian lol

[@hellhound-si5oz]

You might want to change the capacitors

[@themaritimegirl]

Oh yes, I forgot to address that in the video. I haven't since it's not showing any of the symptoms of needing it, but maybe I should just for good measure? 🤔

[@FFcossag]

@@themaritimegirl You probably should. The small caps and especially the 22 µF ones in APC units are notorious for failing. The units tend to run even if they're completely shot, but they're probably not too happy about it, lol.