Troubleshooting Floppy Disk Drives

There is an apparent failure of the floppy disk drive

Explanation: There is a general failure of the floppy disk drive. This generally means either an error message appeared at boot time saying that the floppy drive failed, or other symptoms and analysis has led you to believe that the floppy drive may have failed. Failure usually means that the disk is not accessible or usable at all and does not respond to any attempts to use it. If the floppy drive is usable after booting the hard disk but just will not boot, look here.

Diagnosis: There are many different causes of apparent floppy drive failures. Floppy drives are very simple affairs and outright failure is quite rare--even in old drives. Most of the time it is simply a matter of incorrect installation or configuration.

Recommendation:

• First of all, if you have just installed this drive or have done any other work within the PC box, check this troubleshooting list of common problems.
• Check to make sure that drive has power. Check the power connection to the drive. If possible, try a different power connector.
• Make sure that the cable running to the floppy drive is connected properly and is not loose or crimped.
• If you are just installing this floppy drive, make sure you don't have the cable connected backwards. It is easy with many 3.5" drives to connect the drive backwards because the cable is keyed but the connectors aren't always. Also, don't assume where pin 1 is on the drive, since this tends to vary with different hardware. If the drive's activity light comes on as soon as the PC is booted and stays on, solid the whole time the PC is on, this is a dead ringer for a floppy cable that has been connected backwards to the drive.
• If you are using two floppy drives then you should try to debug them one at a time, otherwise they may conflict with each other and make debugging more difficult. If two drives work separately but not together on the same cable, this usually means you are either using the wrong kind of floppy cable (make sure it has a twist in it) or one of the drives has had its jumpers changed from the default.
• If your floppy cable has five connectors, remember that these are in two pairs of two connectors (each pair being a pin header connector and a card-edge connector, to allow you to connect to either type of drive), one on each side of the twist in the cable. You cannot use both connectors on the same side of the twist in the cable. The A: drive is the one after the twist.
• Make sure that the floppy disk controller is enabled in the BIOS setup.
• Check the BIOS setup and make sure that the correct drive types are selected for the A: and B: drives. Choosing the wrong type of drives can cause a failure to be reported.
• If you have a 5.25" drive that is not working, check the drive for physical interference. These drives are large and I have seen problems like cables hanging down into the mechanics of the drive and impeding its operation.
• If you cannot get the drive to work, the best way to check it is to swap it with a similar drive in another PC. If your drive works in the other PC but its doesn't work in yours, then you likely have a configuration problem. If the opposite happens then your drive is either bad or misjumpered. It is often easier and cheaper just to get a new drive.
• You may have a problem with the floppy disk controller. Try troubleshooting it here.

Explanation: There may be a failure of some sort with the floppy disk controller. On modern systems the floppy disk controller is built into the motherboard; on an older system it is typically found as an expansion card. It is easy to tell which type you have by looking to see what the floppy cable is connected to.

Diagnosis: Floppy controller failures are relatively rare, although they can happen. Sometimes an integrated controller on the motherboard can have a problem, occasionally as a result of a problem with something else on the motherboard. Controller problems can be caused by resource conflicts or misconfiguration.

Recommendation:

• Check the BIOS settings that control integrated resources on newer motherboards, and make sure the floppy controller is enabled.
• If your PC uses a separate floppy controller card, check all the connections to it. Try removing it from its slot and reinserting it; sometimes the card may not be seated properly and this will fix it. If possible, try switching the controller with another one and see if that fixes the problem.
• Check for resource conflicts with the controller on a built-in PC. It usually uses IRQ 6 and DMA channel 2. Most other devices stay far away from these resources since they are a pretty universal standard, but watch out for devices like tape accelerator cards. Sometimes they use the same resources since they work on the floppy interface themselves.
• If you haven't already ruled out the floppy drive itself as a possible problem, you should try troubleshooting it here. You may want to try swapping the floppy drive to isolate the problem to either the drive or the controller.
• If the floppy controller is built into the motherboard, there is a possibility of a motherboard problem. This of course is especially true if other symptoms, such as flaky behavior, are being observed. You might want to troubleshoot it here.

Explanation: The system will not boot from the floppy disk. The floppy drive is usable after booting the system from the hard disk.

Diagnosis: There are occasionally hardware reasons why a drive won't boot, but usually it is a problem with the floppy disk in the drive, or more commonly a configuration issue.

Recommendation:

• Check to see if the system is trying to access the drive before it tries to boot the hard disk (you should hear a brief noise from the hard disk and the activity light should come on). If it is trying to boot the drive, then make sure there is a bootable disk in it.
• There may be a corrupted boot sector on the disk. Try a different disk if you have problems with one. If you are having errors repeatedly, look in this section.
• If the system is not even trying to boot the floppy disk, make sure to check the BIOS setting that controls the boot sequence for the PC. It is possible that the BIOS has been told not to boot from the floppy disk, as a security measure.
• Make sure you don't have the drive accidentally configured as a B: drive instead of an A: drive. See here for more on configuration.
• There may be a problem with the drive or with the drive controller. Usually in this case I think the controller is more likely to be at fault. Swapping the drive with another drive that works in another PC is the best way to determine if the drive or the controller are at fault

Explanation: You are trying to format a floppy disk and the format fails saying that track 0 is bad on the disk. This occurs even with brand new disks, and even after trying several disks in a new box.

Diagnosis: The usual cause of this problem is using the wrong type of media. In particular, it is often seen when people try to format a high-density (1.44 MB) disk as a double-density (720 KB) disk, in either a low-density or high-density drive. Many people do not realize that while high-density drives are backward compatible with the double-density format (if you use the correct parameter when formatting), the media is not. High density media have a different formulation and cannot be formatted to 720 KB, even on a high-density drive.

Recommendation:

• Use only double-density media if you have a double-density drive, or when you need a 720 KB disk.
• If you are using the right media, and you are having problems with one disk, try another one, or another brand.
• Make sure the floppy drive types are properly set up in the system BIOS.
• If problems persist then you will need to troubleshoot the drive.

Explanation: You are trying to format a floppy disk and the format succeeds, but a great deal of the disk is consumed by what the format program says are bad sectors--typically a quarter of the disk or more.

Diagnosis: This problem usually results from using poor-quality or the incorrect type of media in the drive. In particular, sometimes people play games with disks, trying to format cheaper disks as high density. As described here, however, the different media use different chemistry and cannot be interchanged. So the format will limp along and sort of work--except that not only is much of the disk lost to "bad sectors", whatever actually is written to the disk will probably become corrupted relatively quickly as well. If this problem occurs even when using the right type of media, the drive itself is probably at fault.

Recommendation:

• Make sure you are using the right type of media for your drive. With disks as cheap as they are today, there is no reason to fool around with the wrong disks.
• If you are having problems with one disk, try another one, or another brand.
• If problems persist then you will need to troubleshoot the drive.

Explanation: You are receiving errors trying to read the contents of a floppy disk. The contents of one of the sectors on the disk cannot be read.

Diagnosis: Unfortunately, the most common cause of data error or sector not found messages is media failure; floppy disk media is just not that reliable and will eventually fail if used frequently. There are many different factors that can contribute to the failure of floppy disks, and with proper care, they can be made to last a reasonable amount of time, but they all fail if used any significant amount.

Warning: Do not store original work on floppy disks, or use them as a primary storage area for your active files. The chances of failure are too great, and their performance is very low. Use the hard disk instead, and use floppies only for file transfer and backup (if you don't have better options).

Recommendation:

• Make sure you use high-quality media of the right type for your floppy disk drive. Using poor quality media can lead to problems.
• Try ejecting and then reinserting the disk. You'd be surprised how often this fixes the problem.
• There may be dirt or dust on the surface of the disk. Sometimes tapping the edge of the disk on a hard surface a few times will loosen whatever is causing the problem and let you read the disk. I would recommend emptying its contents to a hard disk subdirectory and then discarding the floppy in favor of a new one.
• Clean the floppy drive read heads. Dirty heads can cause read errors, especially if this is occurring with more than one disk.
• Make sure the floppy drive types are properly set up in the system BIOS.
• Try the problem disk in a different PC, if available. Try other disks in this drive. Sometimes a disk will work fine in one floppy but not in another. If you find that one particular drive always has problems reading disks then continue here.
• Try using a different brand of media. Some drives don't seem to like some brands of disks but work better with other ones.
• You can "repair" a damaged disk by using a disk utility such as Microsoft's Scandisk or Norton's Disk Doctor to mark the unreadable sectors as bad and allow the rest of the disk to be used. The data in the bad sector is still lost, but the rest of the file will be recoverable. Such a file should be treated as corrupted--after all, part of it somewhere is missing--and really, using it should only be as a last resort if there is no backup around. Ideally you are using floppies only as secondary storage and can just use the original, clean copy stored on the hard disk. I do not recommend reusing a floppy disk after it starts showing read errors.

Explanation: Your floppy disk drive is giving a large number of read errors, even when using different disks or different brands of disks. (If you just have a disk or two giving errors, you should be looking here).

Diagnosis: This symptom usually means that the floppy drive needs to be replaced. In some cases the problem is that the drive has become misaligned. This can be fixed, but today it is more economical to just replace the drive.

Recommendation:

• The first step to try is to clean the drive. Consistent errors can be caused by dirt or debris on the heads.
• Test to see if the drive is having problems reading all types of disks, or only disks that it did not format. If the drive will read disks that it formats consistently, but will not read disks formatted on other drives, this implies an alignment problem; the drive's tracks are not lined up with where they should be, but if this incorrect alignment is used when formatting then the alignment problem will be masked (until you take the disk to a different PC). You will probably want to replace the floppy drive.
• It is possible that the floppy disk cable has come loose or that there is another similar physical problem, which you may want to double-check.
• Make sure the floppy drive types are properly set up in the system BIOS.
• Try replacing the floppy disk drive with another and see if the problem goes away; it usually will. If it doesn't, you need to troubleshoot the floppy disk controller.

Explanation: While attempting to access the floppy disk, you get an error stating that the drive is not ready.

Diagnosis: The most common cause of this problem is simply trying to use the drive with no disk in it. It can also be caused by a problem with the drive itself or a bad disk.

Recommendation:

• Make sure that there is a disk in the drive and that for a 5.25" drive, the drive door is closed.
• Make sure the floppy drive types are properly set up in the system BIOS.
• Try a different disk and see if the problem goes away. If it does, then the disk you have is damaged or unformatted.
• If the problem persists for multiple disks then the drive has a problem of some sort. Troubleshoot it here

Explanation: While attempting to access the floppy disk, you get a general failure error. The disk may or may not actually be accessed (meaning the activity light may or may not come on) when you try the command.

Diagnosis: The most common cause of this problem is trying to read an unformatted disk. If a working disk produces this problem, and especially if the drive activity light doesn't come on, this points to a problem with the drive or controller.

Recommendation:

• Make sure that you have a disk in the drive that is formatted and working properly. Using an install disk from a software package for testing is a good idea. Try several disks and see if the problem occurs with all of them.
• Make sure the floppy drive types are properly set up in the system BIOS.
• If the drive activity light comes on before the error is displayed then this implies a problem with the drive or with the disk in the drive at the time.
• The disk could be badly corrupted. Troubleshoot corruption here.
• Watch for any known-good disks that stop working after a period of time; there could be a virus at work so be sure to scan for viruses on your hard disk and any floppies you use regularly.
• If the drive activity light does not come on at all when you try to access the drive and immediately you get a general failure error, this implies strongly that there is a problem with the floppy disk controller. (Usually a failure of the drive would cause the disk to not be recognized at all, producing an "Invalid drive specification" error). Troubleshoot the controller here.
• If you can't find any other cause, suspect the floppy disk itself and troubleshoot it in this section.

Explanation: You specified a drive letter in a command that does not exist.

Diagnosis: This usually results from incorrectly typing a drive letter. For example, typing "DIR Q:" will cause this error if there is no Q: volume on the machine. It can also result from a drive not being properly recognized by the system at boot time, for a variety of reasons.

Recommendation:

• Try the command again using the right drive letter.
• If you are trying to access a brand new hard disk before it has been partitioned and formatted (say by booting a floppy disk and typing "DIR C:" you will get this error. The hard disk must be partitioned and formatted before you can use it.
• If you get this error trying to access a floppy disk drive then this means that the drive has either failed or has not been set up properly in the BIOS setup. Check the BIOS settings first; if necessary troubleshoot the drive.
• If you get this error on a CD-ROM drive, then this means that when the system booted, the device was not seen. You should troubleshoot this here.

Explanation: You are trying to eject a disk (usually a 3.5" disk) from the floppy disk drive but it is stuck. Usually this means that you press the eject button, the disk pops up and starts to eject, but then falls back in place into the drive.

Diagnosis: This is usually caused by the metal slider on the disk coming loose and snagging on something inside the drive. If it happens often then it may be the brand of disks you are using, or it could be the drive.

Recommendation:

• Turn the power off to the PC. Then, using a long, thin screwdriver or knife, carefully pry the disk out of the drive. You want to try just to push out of the way whatever is getting stuck, without moving or damaging anything in the drive. This whole process sounds complicated but is in fact quite easy to do.
• If the problem occurs a great deal and you are using only one type of media, try another.
• If the problem occurs even with different types of disk media, the drive probably needs to be serviced or replaced.

Explanation: You have data that you need on a 3.5" floppy disk that has a problem with the metal slider used to protect the data access window on the disk. The slider is stuck and won't move freely so the disk can't be used properly in the drive.

Diagnosis: The metal shutter or slider on 3.5" disks is moved into place using a small spring mounted within the disk. Usually problems related to the slider mean that this spring has fallen out or become misaligned.

Recommendation:

• Just take the metal slider right off. It isn't necessary for the operation of the drive, and this will allow you to access the contents of the disk.
• Copy the contents of the disk to a new disk with a working slider. The metal piece isn't necessary for the disk to be able to be accessed, but it is mandatory for day-to-day use of the floppy disks. Otherwise the surface where the data is stored would be exposed to far too much damage and dirt.

Explanation: There is a general failure of the floppy disk drive. This generally means either an error message appeared at boot time saying that the floppy drive failed, or other symptoms and analysis has led you to believe that the floppy drive may have failed. Failure usually means that the disk is not accessible or usable at all and does not respond to any attempts to use it. If the floppy drive is usable after booting the hard disk but just will not boot, look here.

Diagnosis: There are many different causes of apparent floppy drive failures. Floppy drives are very simple affairs and outright failure is quite rare--even in old drives. Most of the time it is simply a matter of incorrect installation or configuration.

Recommendation:

• First of all, if you have just installed this drive or have done any other work within the PC box, check this troubleshooting list of common problems.
• Check to make sure that drive has power. Check the power connection to the drive. If possible, try a different power connector.
• Make sure that the cable running to the floppy drive is connected properly and is not loose or crimped.
• If you are just installing this floppy drive, make sure you don't have the cable connected backwards. It is easy with many 3.5" drives to connect the drive backwards because the cable is keyed but the connectors aren't always. Also, don't assume where pin 1 is on the drive, since this tends to vary with different hardware. If the drive's activity light comes on as soon as the PC is booted and stays on, solid the whole time the PC is on, this is a dead ringer for a floppy cable that has been connected backwards to the drive.
• If you are using two floppy drives then you should try to debug them one at a time, otherwise they may conflict with each other and make debugging more difficult. If two drives work separately but not together on the same cable, this usually means you are either using the wrong kind of floppy cable (make sure it has a twist in it) or one of the drives has had its jumpers changed from the default.
• If your floppy cable has five connectors, remember that these are in two pairs of two connectors (each pair being a pin header connector and a card-edge connector, to allow you to connect to either type of drive), one on each side of the twist in the cable. You cannot use both connectors on the same side of the twist in the cable. The A: drive is the one after the twist.
• Make sure that the floppy disk controller is enabled in the BIOS setup.
• Check the BIOS setup and make sure that the correct drive types are selected for the A: and B: drives. Choosing the wrong type of drives can cause a failure to be reported.
• If you have a 5.25" drive that is not working, check the drive for physical interference. These drives are large and I have seen problems like cables hanging down into the mechanics of the drive and impeding its operation.
• If you cannot get the drive to work, the best way to check it is to swap it with a similar drive in another PC. If your drive works in the other PC but its doesn't work in yours, then you likely have a configuration problem. If the opposite happens then your drive is either bad or misjumpered. It is often easier and cheaper just to get a new drive.
• You may have a problem with the floppy disk controller. Try troubleshooting it here.

Explanation: There may be a failure of some sort with the floppy disk controller. On modern systems the floppy disk controller is built into the motherboard; on an older system it is typically found as an expansion card. It is easy to tell which type you have by looking to see what the floppy cable is connected to.

Diagnosis: Floppy controller failures are relatively rare, although they can happen. Sometimes an integrated controller on the motherboard can have a problem, occasionally as a result of a problem with something else on the motherboard. Controller problems can be caused by resource conflicts or misconfiguration.

Recommendation:

• Check the BIOS settings that control integrated resources on newer motherboards, and make sure the floppy controller is enabled.
• If your PC uses a separate floppy controller card, check all the connections to it. Try removing it from its slot and reinserting it; sometimes the card may not be seated properly and this will fix it. If possible, try switching the controller with another one and see if that fixes the problem.
• Check for resource conflicts with the controller on a built-in PC. It usually uses IRQ 6 and DMA channel 2. Most other devices stay far away from these resources since they are a pretty universal standard, but watch out for devices like tape accelerator cards. Sometimes they use the same resources since they work on the floppy interface themselves.
• If you haven't already ruled out the floppy drive itself as a possible problem, you should try troubleshooting it here. You may want to try swapping the floppy drive to isolate the problem to either the drive or the controller.
• If the floppy controller is built into the motherboard, there is a possibility of a motherboard problem. This of course is especially true if other symptoms, such as flaky behavior, are being observed. You might want to troubleshoot it here.

Explanation: The system will not boot from the floppy disk. The floppy drive is usable after booting the system from the hard disk.

Diagnosis: There are occasionally hardware reasons why a drive won't boot, but usually it is a problem with the floppy disk in the drive, or more commonly a configuration issue.

Recommendation:

• Check to see if the system is trying to access the drive before it tries to boot the hard disk (you should hear a brief noise from the hard disk and the activity light should come on). If it is trying to boot the drive, then make sure there is a bootable disk in it.
• There may be a corrupted boot sector on the disk. Try a different disk if you have problems with one. If you are having errors repeatedly, look in this section.
• If the system is not even trying to boot the floppy disk, make sure to check the BIOS setting that controls the boot sequence for the PC. It is possible that the BIOS has been told not to boot from the floppy disk, as a security measure.
• Make sure you don't have the drive accidentally configured as a B: drive instead of an A: drive. See here for more on configuration.
• There may be a problem with the drive or with the drive controller. Usually in this case I think the controller is more likely to be at fault. Swapping the drive with another drive that works in another PC is the best way to determine if the drive or the controller are at fault.