Abstract: An object is to automatically detect the positions of spike noise, create a distribution diagram, and perform pass/fail decisions. The cross-correlation function of the signal waveform from a magnetic head 1 and a reference waveform simulating spike noise is used in extraction of spike noise. The number of peaks in the cross-correlation function exceeding a threshold value is counted, and quantitative evaluation of spike noise is performed.

Abstract: A method of connecting a plurality of probe pins to a plurality of first external connection pads, which are provided on a head gimbal assembly and are electrically connected to a plurality of terminal electrodes of a write magnetic head element, respectively, and a plurality of second external connection pads, which are provided on the head gimbal assembly and are electrically connected to a plurality of terminal electrodes of a read magnetic head element. In the connection method, an approach direction of the probe pins to the first external connection pads and an approach direction of the probe pins to the second external connection pads are made different from each other.

Abstract: The present invention provides a method for detecting missing servo patterns on printed recording media. In general, the method first comprises the step of generating a map of anticipated servo burst patterns for a magnetic medium. The magnetic medium is typically a magnetic storage disc. Next, the magnetic medium is placed onto a disc reading assembly. Using the disc reading assembly, individual servo bursts on the magnetic medium are identified. In one embodiment, signals from the magnetic medium are processed through a frequency down conversion process, coupled with band pass filtering and rms-to-DC conversion. This enables higher throughput of signal processing. A map of identified servo bursts on the magnetic medium can then be generated. The map of identified servo bursts is then compared with the map of anticipated servo burst patterns. In this way, missing servo bursts can be detected.

Abstract: A system (10) and method for high-speed massive magnetic imaging on a spin-stand (12) is provided. The system (10) includes a spin-stand system (12) for driving a rotational spindle (20) to which a magnetic hard disk (30) is mounted. A magnetic read head (40) reads data from disk (30) and is in electrical communication with a universal head preamplification board (50). The universal head preamplification board (50) outputs readable voltage signals which are transmitted to an oscilloscope (60) for displaying a read-back voltage display (70). The signals are processed by a processing means (90) to generate scanned image data (100) on a display means. The display signals (70) are utilized to calibrate the magnetically read data to account for the eccentricity of the hard disks with respect to the center of rotation of the spin-stand spindle. Whole tracks of hard disk data can be imaged through the process of “track-centering” and “track-following”.

Abstract: A method is described for calculating head disk interference (HDI) using a dynamic parametric test. In one embodiment, HDI is calculated based on an actual and ideal sensitivity profile based on a read-back signal track profile for the slider/head.

Abstract: A method of testing a performance of the HGA has a step of writing information from the at least one thin-film magnetic head element onto a magnetic disk with driving the actuator for displacement by applying an alternating drive signal to the actuator, a step of reading out the information of at least one rotation of the magnetic disk by the at least one thin-film magnetic head element without driving the actuator for displacement, a step of storing the information read-out from the magnetic disk as a read-out information along a disk-rotating direction, a step of moving the HGA toward an off-track direction by a predetermined distance, a step of repeatedly executing the reading, storing and moving steps to obtain two-dimensional read-out information along the disk-rotating direction and the off-track direction, and a step of determining, from the two-dimensional read-out information, an off-track position where the read-out information becomes maximum at each position along the disk-rotating direction, the

Abstract: A method and apparatus for detecting a high flying condition of a transducer head in a computer disk drive is provided. The method and apparatus allow the detection of high fly write events that occur over one or a small number of data sectors. In addition, the present invention provides a method and apparatus for detecting high fly write events with a great deal of sensitivity. The method and apparatus of the present invention provide quick response and high sensitivity by monitoring the strength of a signal derived from data written to the disk, and signaling a high fly write event if the monitored signal strength in connection with a particular piece of data is less than a stored high fly write number corresponding to that piece of data by a predetermined amount.

Abstract: A method of performing predictive failure analysis (PFA) for a disc drive includes maintaining at least two primary error counts during operation of the disc drive. The primary error counts each correspond to disc drive errors associated with different attributes of the disc drive and are potentially indicative of disc drive failure. Imminent disc drive failure is predicted based upon a combination of the primary error counts.

Abstract: Method of accurately measuring various kinds of non-linear transition shifts (NLTSs) in the magnetic recording/reproduction using an MR-type reproducing head is provided. According to the method, the data of a reference bit-string pattern are sent, as reference signals, to a magnetic disk 2 via a head IC 5 and a magnetic head 3 so as to be magnetically recorded. A first predetermined harmonic component Vnref is measured from the reproduced signals of the record data detected by the magnetic head 3, a bit-string pattern is selected from plural kinds of predetermined bit-string patterns, the data of the selected bit-string pattern are sent, as to-be-measured signals, to the magnetic disk 2, a second predetermined harmonic component Vnpat is measured from the reproduced signals, and the NLTS is calculated from Vnref and Vnpat.

Abstract: A testing apparatus of a magnetic recording medium for conducting a test on the magnetic recording medium by using reproduced data obtained through reproduction of the magnetic medium, including a plurality of conversion means for converting the reproduced data into digital data, holding means for holding the digital data converted by the plurality of conversion means, data processing means for performing a calculation process on the digital data held by the holding means in relation to a magnetic characteristic of the magnetic recording medium, and analysis processing means for performing an analysis to determine whether or not information obtained by the data processing means satisfies a certain condition.

Abstract: An object is to automatically detect the positions of spike noise, create a distribution diagram, and perform pass/fail decisions. The cross-correlation function of the signal waveform from a magnetic head 1 and a reference waveform simulating spike noise is used in extraction of spike noise. The number of peaks in the cross-correlation function exceeding a threshold value is counted, and quantitative evaluation of spike noise is performed.

Abstract: The occurrence frequency of read error occurring when the data on one disk is read by a read unit is compared with that when the data on another disk is read by the read unit and the evaluation result of relatively evaluating the disks is displayed on a display section as the ranking of the disks. Therefore, the user can easily and precisely determine the disk having a good affinity for the apparatus main unit.

Abstract: The magnetic field intensity distribution of a magnetic material sample, such as a magnetoresistive device, is measured with a probe having a tip portion of a magnetic material to which current is made to flow from a power source to the magnetic material. The probe is scanned relative to the surface of the magnetic material sample in two modes. In a first mode, the probe is scanned by being oscillated in a vertical direction to tap a surface of the sample to be tested. In a second mode, the probe is scanned while being held in contact with the measured surface. Corresponding first and second output signals from the two modes of scanning are processed to calculate the magnetic field intensity distribution of the sample magnetic material.

Abstract: A method of measuring the magnetic moment (Mrt) and anisotropy field strength (Hk) of a perpendicular magnetic recording medium comprising a planar-surfaced perpendicular recording layer and a magnetically soft underlayer (SUL) is provided. A compensated magnetic moment (Mrt)comp of the recording layer is determined for a given strength (H) of a generally in-plane magnetic field applied generally to the recording layer. The compensated magnetic moment (Mrt)comp of the recording layer is determined for a plurality of different in-plane applied magnetic field (H) strengths to determine the variation of the compensated magnetic moment (Mrt)comp of the recording layer as a function of the strength (H) of the generally in-plane applied magnetic fields.

Abstract: Methods and apparatus are disclosed determining the presence of base line popping noise for a read head inside an assembled disk drive, as well as, determining read bias conditions for operating the read head free of base line popping noise. These further include performance evaluation of the read head for read bias conditions free of base line popping noise. They also include repairing the read head using DC write current and read bias current within the assembled disk drive.

Abstract: A testing apparatus for testing a disk and/or head of a disk drive that includes a disk rotating device that rotates the disk and a rotary-positioning device that rotates and positions the head, with the rotary-positioning device supporting the head such that the attitude of the head relative to the center of rotation of the rotary-positioning device is tilted in comparison to the attitude of the head relative to the rotation center of the head in the disk drive.

Abstract: A magnetoresistive element measurement circuit configured for measuring resistance of a magnetoresistive element biased by a current source is disclosed. In a preferred embodiment, the measurement circuit includes the magnetoresistive element, a current source providing a fixed current to the magnetoresistive element, at least one current bypass switch controllingly engaging a measurement resistor in an electrical parallel configuration with the biased magnetoresistive element, and an analogue voltage detector measuring voltage first across the biased magnetoresistive element and then across the biased magnetoresistive element in electrical parallel communication with the measurement resistor. The measured voltages are factored with the measurement resistor to determine the resistance of the magnetoresistive element.

Abstract: A transducer position sensing system in a disc drive to take frequent data measurements from micro-servo sectors on the disc and to interpret the information to predict recording failures. The disc drive is formatted with many small or micro-servo sectors containing, among other things, a servo address mark, encoded disc location information, and radial track position information. The sensing system frequently retrieves this information through the transducer, compares the measurements to expected values, and given unexpected measurements predicts errors. The time elapsed between the passing of servo address marks can be used to predict adjacent sector overwrites. The radial track position information can be used to predict off-track write errors. The radial track position signal amplitude can be used to predict the transducer moving too far from the disc, resulting in skip write errors.

Abstract: An XY stage includes a movable frame having a rectangular space inside thereof and movable on a reference base along one of X and Y axes, a first drive source provided in the reference base for moving the movable frame, a rectangular movable base mounted in the rectangular space of the movable frame, which is movable on the reference base along the other of the X and Y axes and stopped on the reference base, and a second drive source provided in the movable frame, for moving the movable base.

Abstract: A circuit and method are presented for detecting a fault in a magneto-resistive head (18). The circuit includes a bias circuit (50) to produce a bias voltage across the head (18) and a pair of resistors (68,70) in series with the head (18) connected to the bias circuit (50) to carry a current (IVMR) from the bias circuit (50) in common with the head. A circuit (102,102′) is provided to determine a ratio of a voltage across the head (18) with respect to a voltage across the head (18) and the pair of resistors (68,70), and a circuit (104,106,104′,106′) is provided for indicating a fault if the ratio falls outside a predetermined range.

Abstract: A method is described for calculating head disk interference (HDI) using a dynamic parametric test. In one embodiment, HDI is calculated based on an actual and ideal sensitivity profile based on a read-back signal track profile for the slider/head.

Abstract: An automated production process for the screening of the read-width (RW) and/or the stripe-height (SH) for every magnetoresistive (MR) read sensor element in a wafer substrate. The method of this invention uses the RW and/or SH values found with optical examination by electron microscopy of several of the MR sensor elements to estimate two substrate coefficients that relates the optical RW and SH measurements to heating-delta measurements, &dgr;=(RH−RC)/RC, where RH is the sensor resistance when hot and RC is the sensor resistance when cold, both of which can be measured using automated equipment. These relationships are sufficiently similar among all MR sensor elements manufactured on a single wafer substrate during a single manufacturing procedure that, when the hot resistance RH is measured at a constant applied voltage, the heating-delta, may be used with a first substrate coefficient to estimate the read-width RW of each MR sensor element for quality-control purposes during manufacture.

Abstract: A magnetic head and disk tester comprises a base, a spindle for rotationally supporting a magnetic disk, a carriage for supporting a magnetic head support which carries a magnetic head with a magnetic read/write element, and a dual-stage positioning system that moves the carriage in two perpendicular directions X and Y. The magnetic head support, the magnetic head and the magnetic read/write element have a common longitudinal axis Z. The head support is positioned such that the longitudinal axis Z forms a predetermined angle between 0° and 90° with respect to the Y direction. Preferably the predetermined angle is about 45 degrees. When the head is driven from one point of an inner track to a point of an outer track, the displacement of the head along X axis is relatively large and the displacement of the head along Y axis is relatively small.

Abstract: A testing apparatus of a magnetic recording medium for conducting a test on the magnetic recording medium by using reproduced data obtained through reproduction of the magnetic medium, including a plurality of conversion means for converting the reproduced data into digital data, holding means for holding the digital data converted by the plurality of conversion means, data processing means for performing a calculation process on the digital data held by the holding means in relation to a magnetic characteristic of the magnetic recording medium, and analysis processing means for performing an analysis to determine whether or not information obtained by the data processing means satisfies a certain condition.

Abstract: A system (10) and method for high-speed massive magnetic imaging on a spin-stand (12) is provided. The system (10) includes a spin-stand system (12) for driving a rotational spindle (20) to which a magnetic hard disk (30) is mounted. A magnetic read head (40) reads data from disk (30) and is in electrical communication with a universal head preamplification board (50). The universal head preamplification board (50) outputs readable voltage signals which are transmitted to an oscilloscope (60) for displaying a read-back voltage display (70). The signals are processed by a processing means (90) to generate scanned image data (100) on a display means. The display signals (70) are utilized to calibrate the magnetically read data to account for the eccentricity of the hard disks with respect to the center of rotation of the spin-stand spindle. Whole tracks of hard disk data can be imaged through the process of “track-centering” and “track-following”.

Abstract: A method is disclosed for detecting defects in a recordable medium such as a hard disc drive based on error energy. The method may include the steps of writing test data to the medium and reading back the test data. The method may also include the steps of computing an error energy based on the square of the difference between the read back data and an ideal version of the test data and comparing the error energy with an energy threshold. The method generates a defect signal when the error energy exceeds the energy threshold. The method may also be used to identify the media defect according to its error energy profile. An apparatus for detecting defects in a recordable medium is also disclosed.

Abstract: A magnetic data storage and retrieval system includes a magnetoresistive head, a resistor, a preamplifier circuit, a voltage measurement circuit, and a resistance calculation circuit. The preamplifier circuit is operably coupled to the magnetoresistive head and the resistor, and applies a first current to the magnetoresistive head and a second current to the resistor. The voltage measurement circuit measures a first voltage across the magnetoresistive head and a second voltage across the resistor. The resistance calculation circuit calculates a resistance of the magnetoresistive head based upon the first and second voltages.

Abstract: The magnetic powder for validity determining ink is composed of magnetic oxide powder having a Curie temperature between −50° C. and 150° C. and a mean powder particle diameter of 10 &mgr;m or less.

Abstract: Method and apparatus for determining the rotational direction of a rotatable article, such as a spindle motor used in a data storage device to rotate a data recording disc. The article includes an index mark which is detected by an index sensor to identify an index reference position on the article. The index sensor and index mark are further used to detect the direction of rotation of the article. In some embodiments, a second sensor is provided so that first and second timing pulses are generated from the index mark by the index sensor and the second sensor. In other embodiments, a second (detection) mark is added to the article so that first and second timing pulses are generated by the index sensor. In either case, a rotational direction detection circuit determines the rotational direction of the article in relation to the first and second timing pulses.

Abstract: A method and apparatus for selecting data densities on disk surfaces in a disk drive based upon measured thermal decay rates of the disk surfaces is disclosed. First and second data patterns having first and second data densities, respectively, are written onto a first disk surface. The first and second data patterns are read, upon expiration of at least a first predetermined time interval, and first and second thermal decay rates associated with the first and second data patterns, respectively, are calculated. A determination is made as to whether the first and second thermal decay rates, respectively, satisfy first and second thermal decay rate requirements. Finally, a density at which to record data on the first disk surface is selected based upon whether the first thermal decay rate meets the first thermal decay rate requirement and whether the second thermal decay rate meets the second thermal decay rate requirement.

Abstract: A testing apparatus of a magnetic recording medium for conducting a test on the magnetic recording medium by using reproduced data obtained through reproduction of the magnetic medium, including a plurality of conversion means for converting the reproduced data into digital data, holding means for holding the digital data converted by the plurality of conversion means, data processing means for performing a calculation process on the digital data held by the holding means in relation to a magnetic characteristic of the magnetic recording medium, and analysis processing means for performing an analysis to determine whether or not information obtained by the data processing means satisfies a certain condition.

Abstract: A structure is integrated into the design and manufacture of a magnetic head that allows self-generation of magnetic fields. The structure includes a conductor or conductors placed in close proximity to the read portion of a magnetic head and connected to an externally accessible connection. A high frequency signal is passed through the conductor to generate a magnetic field through the read device and simulate, for example, the head crossing magnetic domains on a magnetic memory disk.

Abstract: A testing apparatus for a magnetic head or a magnetic disk, includes a magnetic disk; a magnetic head moving mechanism which holds a magnetic head and which moves the magnetic head to a predetermined position in a radial direction of the magnetic disk; a movement mechanism control device for driving the magnetic head moving mechanism, wherein the movement mechanism control device moves the magnetic head moving mechanism to a predetermined radial position corresponding to position data; a read/write control device for writing a predetermined magnetic signal on the magnetic disk using the magnetic head, and for reading a magnetic signal of the magnetic disk using the magnetic head; and a memory for storing therein position data embedded in a data surface of the magnetic disk, extracted from the magnetic signal which is read by the read/write control device. A testing method is also disclosed.

Abstract: A method for non-destructive measurement of dynamic coercivity is disclosed. In this method, magnetic media is DC erased by applying a forward DC magnetic field to the magnetic media such that the magnetic moments in the magnetic media are substantially aligned. A specified number of reversed magnetic field pulses are then applied to the magnetic media in a direction opposite to the forward DC magnetic field, wherein the intensity of the reversed magnetic field pulses is less than the remanent coercivity of the magnetic media. The broadband medium noise of the magnetic media is measured. The intensity of the reversed magnetic field pulses is then repeatedly and incrementally increased and applied to the write head for the specified number of pulses, the intensity of the reversed magnetic field pulses eventually exceeding the remanent coercivity of the magnetic media. For each intensity level of the reversed magnetic field pulses, the broadband medium noise is again measured.

Abstract: A magnetic-disk evaluation apparatus includes a magnetic head positioned relative to a magnetic disk including temporary servo signals. Fluctuation of a magnetic head in a seek direction is measured using a measurement device. A measuring rotating arm moves in tandem with a rotating stage holding a rotary positioner. The measurement device is on the measuring rotating arm. The rotary positioner is controlled on the basis of temporary servo signals to position the magnetic head on a circle, concentric from a center of a spindle motor. Fluctuation of the magnetic head in the seek direction is measured to detect the displacement of the magnetic head and to determine whether the temporary servo signals are acceptable based upon the displacement and an outside standard.

Abstract: A magnetic head that includes a magnetoresistive effect read head element is tested by applying a varying magnetic field and measuring the resulting output signals from the read head element. The output signals are digitized and a processor calculates, e.g., the root mean square (RMS) of the signals or performs a Fast Fourier Transform or Autocorrelation on the data to determine if there is noise present. If desired, write and delay events may be performed prior to digitizing the output signals from the read head element to determine if additional noise, which is introduced to the magnetoresistive head from the write element, is present. In one embodiment, the digitizer may be replaced with an RMS meter.

Abstract: A head testing apparatus is provided for testing an output of a magnetic data recording head. The apparatus includes first and second tester input terminals for coupling to the head, first and second input stages and an AC-coupled differential amplifier. The first input stage has a first buffer input, which is coupled to the first tester input terminal, a first buffer output and a plurality of parallel-connected buffer amplifiers coupled between the first buffer input and the first buffer output. The second input stage has a second buffer input, which is coupled to the second tester input terminal, a second buffer output and a plurality of parallel-connected buffer amplifiers coupled between the second buffer input and the second buffer output. The AC-coupled differential amplifier has first and second amplefier inputs coupled to the first and second buffer outputs through first and second capacitors, respectively, and has a measurement output.

Abstract: A magneto-resistive device with built-in test structure. The magneto-resistive device includes a slider having first and second lower termination pads and first and second upper termination pads. A first conductive trace element electrically couples the first lower termination pad to the first upper termination pad and a second conductive trace element electrically couples the second lower termination pad to said second upper termination pad. The magneto-resistive device also includes a magneto-resistive transducer deposited on the slider and the resistance of the magneto-resistive transducer is obtained by passing an electrical current between the first and second lower termination pads and measuring a voltage across the first and second upper termination pads.

Abstract: The support that bears and positions the head in a head holding apparatus is further supported by a heat-compensating member, so that when the support is expanded by the heat source of the head holding apparatus, the heat-compensating member expands in the direction opposite to the direction of expansion of the support. Moreover, supplying of heat to the support and heat-compensating member is further alleviated by insulating said heat source with an insulating material. The amount of displacement of the recording element per unit of time with exposure to heat is controlled by the above-mentioned structure and effects.

Abstract: A method for magnetically measuring the magnetic read width (MRW) of magnetic recording heads having a track width that is equal or smaller than the wavelength of visible light is provided. The heads comprise a magnetic read head spin valve sensor and the magnetic read head sensor signal is used to derive an unknown track width from comparing to the sensor response of a known track width. Using this method, track widths in the regions at the wavelength of light and below (<500 nm) can be directly measured without destroying the respective sensor material.

Abstract: In a magnetic head measuring apparatus for measuring a magnetic head, an amplitude-modulated electric current whose amplitude is modulated by a specified carrier wave frequency and modulation frequency is applied to a magnetic head. A calibrating magnetic field generating source causes the magnetic head to generate a magnetic field having a specified strength and frequency, thereby calibrating measurement variations of the magnetic head. A magnetic head measuring device measures a high-frequency magnetic field generated from the magnetic head. If necessary, an interchangeable magnetic material probe is used to replace a probe of the magnetic head measuring device.

Abstract: An apparatus and a method for measuring signal decay of a magnetic recording medium using an approach in which a control track and a track of interest are located on one track are disclosed.

Abstract: A method for indexing magnetic disks by using a scanning probe is disclosed. A magnetic disk includes several essentially concentric magnetic tracks. The magnetic disk is attached to a rotating spindle. A number of data tracks is then written in a specific circular arc at an inner radial position of the magnetic disk. The beginning or the end of the written data tracks is defined to be in a co-incident or in a defined relation to an index or trigger signal defined by the rotating spindle. The rotating spindle is stopped from rotation, and a scanning probe microscope is moved radially at a fixed rotating angle to a second radial position. A tip of the scanning probe microscope is moved towards a surface of the magnetic disk. At least one scan line is recorded and analyzed in order to determine if a magnetic track is imaged by the tip of the scanning probe microscope.

Abstract: A method of determining a clearance between a magnetic transducer and a magnetic recording medium during a track seeking operation, the magnetic recording medium being moveable with respect to the transducer and including at least a test track and a reference track, which method comprises the steps of: at least partially erasing a predetermined area of the recording medium including at least one test track and one reference track; writing a first series of predetermined magnetic transitions along a spiral trace, formed by seeking operation of the transducer, on the at least one test track in the predetermined area; reading the test track and obtaining a pulse width of signals read back from the test track (test track pulse width) at a predetermined amplitude level; writing a further series of predetermined magnetic transitions identical to the first series on a reference track of the recording medium in the predetermined area; reading the reference track and obtaining, a pulse width of signals read back from

Abstract: A method and apparatus to qualify heads to be used in disc drives. The method and apparatus collect a set of track scan data by moving the head across transitions in a track on a medium. The track scan data is changed based on a difference between a writer width of the head and a nominal track width to produce modified track scan data. Position error signal data is then determined from at least some of the data in the modified set of track scan data. The linearity of the position error signal data is used to qualify the head.

Abstract: A method for indexing hard disks by using a scanning probe is disclosed. A hard disk includes several essentially concentric magnetic tracks. A scanning probe is initially positioned at a first point located on a magnetic track to mark the first point as a first radial position index. Then, the scanning probe is positioned at a second point located on the magnetic track to mark the second point as a second radial position index. Next, the scanning probe is positioned at a third point located on the magnetic track to mark the third point as a third radial position index. A rotational center of a co-ordinate system is subsequently calculated according to the three radial position indexes. Finally, the co-ordinate system having the rotational center is utilized as a precise indexing system.

Abstract: A test stand and method for testing a disk of a hard disk drive. The disk is placed onto a spindle motor of the test stand. The test stand also contains a head that is connected to a controller. The controller causes the head to write a reference signal and a test signal onto the disk. The amplitude of the reference signal is then reduced, typically with a DC erase current. The head reads back the test signal from areas of the disk that are heated by a heating element. The reference signal is also read back and used to normalize the test signal. Using a reference signal with a reduced amplitude has been found to produce less scattered data than methods of the prior art.

Abstract: The magnetic powder for validity determining ink is composed of magnetic oxide powder having a Curie temperature between −50° C. and 150° C. and a mean powder particle diameter of 10 &mgr;m or less.

Abstract: A combination glide test/burnishing head can be utilized in a glide test/burnishing system. The combination glide test/burnishing head includes two piezo-electric elements, which can be utilized in a passive mode as sensors for detecting contacts between the glide test/burnishing head and asperities on the surface of a magnetic recording disc. Contact between the glide test/burnishing head and disc asperities results in generation of a defect detection signal, which can be utilized by associated test logic to define the location of the detected asperities on the disc surface. The piezo-electric elements of the glide test/burnishing head can also be utilized in an active mode to cause yaw variation in the flight attitude of the glide test/burnishing head, in turn causing a burnishing pad on the glide test/burnishing head to be moved radially into contact with a detected disc asperity.

Abstract: An apparatus and method for detecting and marking delamination defects on thin film disks are disclosed. The apparatus includes a read/write (R/W) head and a burnishing head mounted on separate arms that access the disk while spinning on the test stand. The controller uses the R/W head to perform an initial magnetic test of selected areas on the disk to establish an initial defect map. The burnish head is then flown over the surface for an extended time to accelerate and open up the latent delamination defects by impacting protruding material. The R/W head is then used to perform a second magnetic test which is compared against the first test to identify the delamination defects which have been developed by the burnishing. The delamination defects are then marked with a magnetic pattern which aids in optically locating the defect during subsequent failure analysis.