@Daniël My thoughts exactly! I've never seen an OEM one with a voltage switch.
I've just found the book I was referring to, which I probably should've done before posting this thread as it does answer my question about the pictured power supply. This book is really worth a read for anyone interested in Mac power supplies in general, and I learnt a lot when I first read it.
The book is called "Troubleshooting Your Macintosh" by Douglass High published in 1992 and it's available for download from vintageapple.org.
It starts out by rubbishing Apple's OEM PSUs on page 137 (151 in the PDF), which I generally agree with since my own experience of them has been quite eventful:
The Achilles' heel of Macintosh computers has always been the power supply. Simply put, Macintosh power supplies are expensive and prone to constant failure. In fact, many Macintosh computers have barely enough power to sustain even a mild upgrade such as additional memory or a hard drive.
The book then goes into some electronics theory about PSUs, which I found very helpful when first trying to wrap my head around "what even happens inside this box?".
In contrast with some books which rubbish the Astec PSUs often found in Mac II series machines, this book seems to think they were OK and puts most of the fault/blame with the spec Apple gave Astec to work with...
The Astec power supply used in the llcx, llci, and Quadra 700 is a well-built unit. Astec makes excellent power supplies. Unfortunately, the specifications that Apple gave Astec and other vendors to work with were pretty bad. The approximate 90 watts of out- put is on the low side. It should be around 150 watts to accommodate the majority of memory and hard disk drive upgrade paths.
By comparison, the Mac Bible says the GE was a more reliable unit than the Astec.
Anywho... back to the third party PSUs I was referring to in my original post. This is where it starts to get interesting.
Bearing in mind this is 1992 information, but I still find it very interesting (especially in bold).
Q. If my original Mac power supply dies, should I replace it with another Apple power supply or with a third-party supply?
A. That depends. If your Macintosh is still under warranty, you should go to your local dealer for immediate warranty service. Don't open up the power supply. I f the machine is under warranty, you may void it.
If the machine is out of warranty, that's a different story. I would never purchase any power supplies that Apple has spec'd out. Their power supplies are mediocre and expensive. In addition, Apple won't sell repair parts to individuals; they go through their service channels only. These service providers aren't supposed to allow end users to do their own repairs. They usually require that you bring your machine to them, wait until they have time to fix it, pay for parts and labor, and give them your old parts that Apple recycles. These costs add up.
Keep in mind that most (if not all) Mac power supplies are marginal. (Could it be built in obsolescence?) Why would you want to pay for and put something marginal back into your machine? If it's your nickel, you should purchase a third-party replacement supply rated at least double what your original supply was.
Now, some of that might be a bit subjective, but let's go with it for the sake of argument right now, as this is obviously 1992, I have a broken Mac and Apple's PSUs are too expensvie for me! ... the most relevant bit in bold.
Q. Where can I purchase third-party power supplies for the Macintosh?
A. I know of only two companies that currently manufacture replacement Macintosh power supplies: Quadmation and Power Plus Systems (PPS).
Recently I had an opportunity to evaluate and benchmark power supplies from both companies. Being an expert in electrical engineering and design, I really put these units through their paces. The results were mixed. The Quadmation Ilcx power supply I evaluated performed worse than Apple's. My Mac would not come on and stay on. Their technical support was unfriendly and not very helpful. When I inquired how to return this power supply for a refund, I was given a hard time. I would be surprised if the unit they shipped me would pass either UL or FCC certification.
The second company I evaluated was Power Plus Systems in Salt Lake City, Utah. I evaluated their Ilcx/IIci/Quadra 700 power supply in the same manner as I did the Quadmation unit. The Power Plus unit was superior in every way to both the Quadmation and the Apple unit. I got at least twice the power of the Apple model at one half the price. When I had questions, they answered them promptly and intelligently. The president, Craig Rosenthal, even got on the line to see how I liked the unit. (He didn't even know me!) They also have a very generous two-year warranty. Double thumbs up to Power Plus Systems. You can contact PPS at 1-800-722-0602.
Now there's the ticket -
Power Plus Systems. So the IIci PSU I found there is indeed a unit from PPS, suggested by the model number
PPS-102 ! It's the first time I've seen one of these in the wild, and I probably shouldn't get this excited about something as dull as a third party Mac power supply from the early 90s, but this is... cool, right?
