Last week I wanted to test some half-height eight-inch double-sided drives (NEC, Mistubishi, and Qume) on the Quay 900. I cabled a Mitsubishi drive in place of the original CDC/MPI 9406 77618022 drives, and the machine apparently wouldn't reset properly, since I wasn't getting the prompt from my ROM monitor either on power-up or by manually resetting it. I poked around a bit and discovered that the +5V DC supply was at about 0.7V. I disconnected the Mitsubishi, and it still didn't work, and the +5V was still at 0.7V. Uh oh, what did I break? After a lot of pulling of hair, gnashing of teeth, and sacrificing a chicken at midnight, I discovered that +5V pin in the connector that plugs onto the switching power supply was not crimped properly. It was partially crimped, but the wire was just loose. The cable connector is an AMP (now TE) 87025-7 "Ampmodu" 0.156-inch pitch shell which accepts 102103-3 rectangular crimp receptacles. The shell has 20 positions, of which they inserted a keying plug in position 1, and only use contacts in some of the even positions from 2 though 20, because the header on the power supply PCB only has every other pin loaded. TE no longer makes the 87025-7, but they still make the 87025-8, which is apparently the same thing without the part number being stamped on the housing. I don't need another housing though, just a pin, because without the right extraction tool I hadn't been able to get the old pin out without mangling it a fair bit. Mouser and Digikey sell the pins in small quantity for $0.50 each, which seems absurdly high for a crimp pin with only tin plating. (There's another part number for a gold contact, but distributors don't stock it.) Just for the hell of it, I looked up the TE manual (hand) crimping tool designed for this pin, p/n 90274-2. It sells for over $6500. There is a used one on eBay for $75, but I've had bad experience buying used crimping tools. The only crimping tool I have on hand is designed for terminals with a round shell that just have to be crimped flat, vs. for terminals with V-shaped edges that have to be folded back in, as is typical of Molex pins and the like. I decided to order an inexpensive ratcheting crimping tool from an Amazon seller. It's an Iwiss SN-28B, also sold under the Estone and other brands. The Iwiss was $19. I couldn't tell from the photos whether it would be suitable. It turns out that it worked perfectly for the TE pins. It has two pairs of dies stacked with one pair having a larger profile, so it does crimp both the conductor and the insulator at the same time, which I wasn't expecting for a sub-$20 tool. That got the machine working again, and I verified that the CDC/MPI drives are still working, or at least working as well as they were before. I'm still seeing a lot of unreliability when using double-density on the highest-numbered tracks (closest to spindle). Could be the wrong amount of precomp, or the low-quality data separator design. Since one of the two MPI drives gets more errors than the other, there may be some issue with drive alignment or drive electronics adjustment as well. I unplugged the MPI drives and plugged in the Mitsubishi. Once again the machine wouldn't reset properly. It turns out that even though this bizarre variant of the 9406 uses the Shugart pinout for the data connector instead of the MPI pinout, and uses the same DC power connector as the Shugart, instead of the header used in normal MPI 9406 drives, the DC power connector pinout for the MPI does NOT match the Shugart DC pinout, as also used by the various half-height drives I want to try. I'm becoming less and less impressed with these MPI drives as I learn more about them. With the Mitsubishi cabled up to the Quay, but using a separate DC power supply with the correct pinout, I was able to verify that the Mitsubishi drive actually works fine. When used with the Quay FDC, it does need some retries for double-density on the inner tracks, like the MPIs, but it doesn't need as many retries as either of the MPI drives.