Is there any photos of what a CompuPro mini drive enclosure looked like? My Google foo isn't turning up anything.
There isn't a specific Disk Enclosure for 5.25" drives. Compupro made two Drive Enclosures that would house two 8" rackmount drives horizontally, side by side. The 1st/Original Version was made to house two full size 8" floppy drives (never meant to house an 8" hard drive). You can spot the early disk drive enclosures by the fact that it about two inches deeper than the 2nd design, and has five screws holding the chassis to the cover on each of the two sides (the shorter chassis 2nd design has four screws holding the chassis to the cover on both sides). The early long chassis had a single punchout for a 50-conductor connector. Later long chassis had additional punchouts for a 20-conductor and a 34-conductor for a 5.25" hard drive or mini-floppy drive. The on/off switch was mounted on the rear and was the same size as the Compupro Mainframe on/off switch.
There was also a 3rd, short-lived intermediate length chassis design, shorter that the early long chassis, and longer than the later short chassis which was offered for a short time between when the 8" full height floppy drives were offered, and the introduction of 5.25" half height drives (mini-floppy and tape). These not not seen very often. The rare intermediate length chassis is most often seen with 8" half-height floppy drives, and carries the full size on/off rocker switch of the S-100 Mainframe.
Short chassis came with the same full size switch when introduced but switched to a smaller rocker switch (like the switching power supply Mainframes used), and came with one punchout for a 50-conductor 8" floppy connector, and two sets of punchouts for 5.25" hard drives or mini-floppy drives.
Compupro designed and built different adapter plates/mounting brackets to fit different size drives in different configurations adapting the 8" drive bays to 5.25" full height and half height drives, as well a half height 8" floppy drives. There were brackets to mount two 8" half height drives stacked vertically, single 8" half height drives with a cover over the top half of the bay, 8" half height drive with a 5.25" half height drive mounted above, 5.25" full covers that a hard drive could be hidden behind, and brackets with an opening to fit a full height, or two half height 5.25" drives , and another mounting bracket with an opening to fit a single half height 5.25" drive. At one time I had dozens of extra mounting brackets in stock (order them from another Compupro Authorized Dealer who had high quality duplicates of the Compupro brackets made). My supply of mounting brackets is about exhausted now, and I've played with the idea of looking for a company to duplicate the various brackets. But I'm concerned that I won't be able to get my money back due to the small market.
There were also three power supplies with a standardized mounting base that could be fitted to either chassis size. The original power supply was designed for/to run 8" floppy drives and had outputs for 24V+ and 5V+. The 2nd design has five outputs and is designed to run up to three drives of two types (8" floppy, 5.25" mini-floppy, 5.25" tape drive, or 5.25" hard drive. The 3rd design has up to six voltage outputs and will handle up to four drives of three different types at the same time.
The 2nd and 3rd power supply designs were configured at Compupro for each individual order from an Authorized Dealer. There were different transformers mounted,depending on what outputs were specified. Individual outputs used the same power/bypass transistors, but control components were changed to get the specific voltage outputs required.
At one time I had five to ten spare power supplies tested and ready to sell or exchange, and another five to ten power supplies I was using for parts. The number of spares has been used up or sold over the years, and now I'm down to the last half dozen power supplies and parts donors. Transformers are scrapping bottom for spares. I can still repair power supplies, and in general they are extremely reliable. People usually buy power supplies when they are upgrading their Drive Enclosures from 8" floppy only to a different configuration that includes some sort of 5.25" drive/s.
Right now I have one used long chassis and one new short chassis left for sale. Prices will vary depending on options chosen (advanced power supply and/or drive mounting brackets). The older long chassis starts at $300 with the original 8" only power supply and no additional drive mounting brackets (none required to mount 8" full height drives). The short chassis will start at around $500 with the dual 8" power supply,and extra charge for an advanced power supply or drive mounting brackets. Compupro offered two different colors for cabinets over the years and I think I have used covers in both colors available. I suppose that I could could find a source for chassis/bases I could build a few more complete Disk Enclosures with mostly Compupro parts. Full height drivesdo not fit in the short chassis.
I have two Drive Enclosures connected to my personal system, and if you want to see what the late enclosures (in the late color) look like with an assortment of 8" and 5.25" drives installed, send me your email address, and I'll send you a couple of photos.