A WD My Passport 4TB was dropped, and now it ticks and isn't recognised. The owner opened it up and watched what happens: the head starts in position, sweeps out across the disk, then flicks back, over and over again. The owner has made a very detailed and accurate account of the failure, and it names the fault exactly. The head is looking for the servo pattern written on the platter (the servo pattern is used by the drive to keep track of its own location). It can't read it and thus can't settle, so it retracts to the ramp and tries again, and the ticking noise is the head retracting each time. There are two things to do with that information. First, the drive should be stopped immediately, as each sweep is a damaged head passing over the surface holding the data. Second, accept that the drive has now been opened up, and there's the risk of contamination in addition to the already existing head failure.
| Media | A WD My Passport 4TB was dropped. There is a ticking noise. It is not recognised. The customer opened up their own device and saw the head moving back and forth across the platter and then retreating over and over again. |
| Reported situation | WD My Passport 4TB · dropped · not recognised · ticking · opened, head seen to sweep over the disk and flick back · recovery sought. |
| Fault class | The head fault was caused due to the impact. This causes the head to lose track of the servo pattern; therefore, it continues to sweep, does not find a steady position and then retreats, causing the tick. The data on the platters is usually unaffected and can be retrieved using the same type of donor head. Repeated power-ons are the greatest risk factor for damage and since this unit was opened earlier, assessment will have to consider the possibility of contamination. |
| Equipment used | Not run further given the fall and the observed head behaviour · put on a bench supply with the current limited and profiled, the sweep-and-retract pattern characterised · opened under laminar flow, contamination from the earlier opening inspected and cleaned, head stack and platter surfaces examined under the microscope at magnification, a matched donor head stack installed and the alignment set · imaged on DeepSpar with PC-3000 UDMA driving the drive, data located and validated in R-Studio. |
The reason to explain the servo pattern is that all of this depends on it. A very specific positional pattern is written onto each platter during manufacture, telling the exact position of the head in wedges of information across every track. It is impossible for the head to locate itself or come to rest on a track without first reading that positional pattern. Finding it is what drives do at the beginning of every read they will ever perform.
So, if you have a head that sweeps, fails and snaps back, it is a head that can't read the servo, and after a fall that is likely to be due to the usual causes: damage to the head; a chip in the slider; or debris from the impact interfering with the reading of the servo. Since the firmware has no other plan than to retreat and try again (the tick), it will continue this process until either something changes or there is an external intervention.
The observations collected are useful in their own right; however, the manner in which they were collected is not. Viewing the heads of a hard drive by opening the drive case allows for the introduction of room air into the space above the platters. Particles are extremely large at the flying height of the heads and will have an impact on the recovery process. That does not necessarily mean the data can't be recovered, but it now involves another step prior to recovery, visually inspecting the platters using a microscope or other form of magnification and cleaning them. Uncertainty has been introduced that was not present previously.
The work itself is a head replacement with matched donors, and the outcome will depend upon the platters. A 4TB portable hard drive from this era is a high density shingled mechanism with tight tolerance, making it less tolerant to contaminants or repeated sweeping, compared to older mechanisms. That alone was reason enough for it to have been turned off immediately when the first tick occurred.
It was not run further, since the fall, the tick and the observed sweep-and-retract left nothing to establish by powering it. It was run from a bench supply with the current limited, where the pattern was characterised in a few seconds. It was then opened under laminar flow, and the first job was inspecting the platters under the microscope at magnification for what had settled during the earlier opening, and cleaning it. The heads had failed. A matched donor head stack was fitted and the alignment set afterwards, and the drive imaged on DeepSpar with PC-3000 UDMA driving it. The filesystem was reassembled in R-Studio off the image and the contents opened and checked before anything went to fresh media.
The heads were changed and the contamination caused by the owner's initial inspection removed, then the drive was imaged and the files placed back on new media. There was no charge for the assessment. One fixed written price for the repair with VAT included prior to commencement of the repairs (the first half being due before the heads were replaced and the balance only on the result). A total of two honest notes were given. The owner provided an accurate description and as a result diagnostic time was minimised. In addition, the owner's initial inspection opened up additional risk which could have been avoided; since all relevant information had already been obtained through the tick and fall, there was no need for the lid to be removed to establish this.
Turn it off and don't open it. If it's already been opened, place the top cover back onto the unit to prevent additional dust from entering the unit and be clear in your correspondence about this, as it will affect how we approach the repair of the unit, and what can realistically be done with it. One tick after a fall is all you need for a diagnosis: the head is unable to read the servo pattern and therefore keeps trying. Each time it tries, the damaged head moves over the area where your data resides. Watching it fail will not help anything but contaminate the drive. Don't manually rotate the platter, don't touch anything within the unit, and please do not try to replace the heads yourself using an online tutorial/video. First get a quote for the service and then box it up whole, including the cable, and note how many times the unit has been turned on since falling down. Send it tracked (you can also drop it off at our Edinburgh lab, Monday to Friday, 9am to 5:30pm, no appointment needed).
Each file below comes from a genuine enquiry taken from households and firms across Aberdeen, Aberdeenshire and the wider north-east, anonymised so nobody can be identified. Each one sets out how the fault was reasoned through, what was done about it, and which equipment did the work.
A shop that says a part inside is broken has read a dropped drive correctly — that part is the head assembly, and it is changed in clean air
A socket that has been strained once and then yanked has failed at the connection, and the drive is read past it rather than through it
A drive that tries to start and gets no further has failed at the heads — the light and the noise are the last two things it can still do
Data recovery assessment is free and will take 2 working days at most once this item arrives. We will then provide written confirmation as to what our fixed fee will be for data recovery services. For logical work, in most cases you only pay if we recover your data. We encourage you to begin the process through our website or simply pick up the telephone.