Before you start, examine the drive to verify the location of pin 1 on the data connector, because it may be impossible to determine which is pin 1 once the drive is installed in the computer. Most drives use an unshrouded and unkeyed connector, many of which are very poorly labeled. Some do not label pin 1 at all. On all such drives we have seen, pin 1 is located nearest the power connector. Better drives use a shrouded and/or keyed connector like that shown in Figure 6-3, and are a better choice.

Figure 6-3. This NEC 3.5" FDD uses a shrouded cable connector rather than the typical bare pins (note the missing pin at lower left, which keys the connector)

Once you have located pin 1 on the drive, connect the FDD data cable to the drive, aligning pin 1 on the cable (the side with the red stripe) with pin 1 on the drive. Do this before you install the FDD in the drive bay, particularly if you are using a drive with an unshrouded data connector. Otherwise, it's very easy to install the data cable offset by a column or row of pins. We know, because we've done it frequently. Be very careful when installing the cable, because it's quite easy to bend pins on an unshrouded connector. Once you're sure the cable is aligned properly with the connector, place your thumb in the middle of the cable connector, as shown in Figure 6-4, and push gently on the cable connector until it seats fully.

Figure 6-4. Connect the cable to the FDD, with pin 1 oriented properly and all pins aligned

In most cases, the FDD installs from the front, but in some cases it installs from the rear. If the drive bay requires installing from the front, slide the FDD into the bay, using your free hand to feed the cable through without kinking it, as shown in Figure 6-5. In most cases, you must leave the FDD projecting half an inch or so in front of the metal chassis so that the FDD bezel will align properly with the case bezel once it is installed. Most 3.5" FDD bays have round screw holes positioned properly to ensure that everything aligns once the case bezel is replaced. Some, however, have elongated slots rather than round holes. On these cases, you may have to align the FDD by trial and error.

Figure 6-5. Slide the FDD into the drive bay, making sure the cable feeds smoothly into the case interior

Once you have properly aligned the screw holes in the drive bay with those in the drive, insert the screws and tighten them until they are fully seated. Do not overtorque the screws. The number of screws required and their positions depend upon the particular FDD and case. Most FDDs and cases allow you to install as many as eight screws—two in front and two in back on each of the two sides. That's complete overkill. We generally use four screws, top-front and bottom-back on each side. Some cases make it very difficult to install screws to support the right side of the FDD (as you face the front of the case). In such cases, we generally install screws in all four positions on the left side of the drive and leave the right side unsupported. If your case is one that requires trial-and-error alignment to get the front of the FDD lined up with the front of the case, insert only two screws initially and tighten them down only enough to allow the FDD to slide in or out with some resistance. Then, replace the front system bezel, get the FDD aligned just right, tighten down the two screws you already installed, and then install the remaining screws. If you're a belt-and-suspenders person, place a small dab of nail polish on each screw head to prevent it from vibrating loose.

With the drive securely fastened to the chassis, connect the power cable to the drive, as shown in Figure 6-6. The power cable and connector are keyed, and so can fit only in the proper orientation. But be careful to align everything properly before you press the connector into place. Some drives use fragile pins on the power connector, and we've bent more than one set when attempting to connect power to an FDD in an awkward situation, such as working under a desk in near darkness.

Figure 6-6. Connect the power cable to the FDD, making sure the connector is aligned properly with the pins