Abstract: A method for maintenance checking of a dental handpiece is disclosed. The method comprises measuring in advance no-load current values of a drive motor, with a handpiece known as being in usable condition and a handpiece known as insufficiently maintained respectively connected thereto and operated in no-load condition, storing as reference data the no-load current values of the drive motor together with associated data relating to degree of maintenance, measuring a no-load current value of the drive motor with a dental handpiece to be checked connected thereto and operated in no-load condition, and determining whether the handpiece checked is usable, requires maintenance, or is unusable, by comparing the measured no-load current value with the reference data.

Abstract: A method for maintenance checking of a dental handpiece is disclosed. The method comprises measuring in advance no-load current values of a drive motor, with a handpiece known as being in usable condition and a handpiece known as insufficiently maintained respectively connected thereto and operated in no-load condition, storing as reference data the no-load current values of the drive motor together with associated data relating to degree of maintenance, measuring a no-load current value of the drive motor with a dental handpiece to be checked connected thereto and operated in no-load condition, and determining whether the handpiece checked is usable, requires maintenance, or is unusable, by comparing the measured no-load current value with the reference data.

Abstract: A servo writing device which writes servo data in each sector of each track of a magnetic disk, wherein servo data recorded positions of the tracks are mutually corresponded. The servo writing device includes a clock head for generating reference clock signals and a standard clock generating circuit generating standard clock signals, whose frequency is higher than that of the reference clock signals and which is not synchronized with the reference clock signals. The device further includes a start pulse generating circuit receiving the reference clock signals as clock signals and generating a start pulse corresponding to the servo data recorded position and a synchronizing circuit synchronizing the start pulse with the standard clock signals and generating a synchronizing-start pulse. In addition, the device also includes a pattern generating circuit receiving the standard clock signals as clock signals and generating the servo data synchronizing with the synchronizing-start pulse.

Abstract: The servo data writing device has a simple system and small structure. The servo data writing device, to which a magnetic disk drive unit, which includes: a magnetic disk attached to a spindle; a magnetic head for writing data onto and reading data from the magnetic disk; and an inner actuator for moving an arm holding the magnetic head in the radial direction of the magnetic disk, is attached and which writes servo data in each track of the magnetic disk with the magnetic head, comprises a non-contact position sensor for detecting a position of the arm from outside of the magnetic disk drive unit without contact. The servo data writing device detects the position of the arm by the non-contact position sensor and controls an inner actuator control circuit, which is assembled in the magnetic disk drive unit, so as to position the magnetic head.

Abstract: For a print-circuit board 10 of a good product, probes 31 and 32 are made to be electrically continuous with a ground plate 13 and a wiring pattern i respectively to measure a capacitance Cgi, which is then stored in a storage device 44. A capacitance Ci of a print-circuit board 10, the object of testing, is measured in a similar manner and a ratio .mu.=(average value Ca of a several measured capacitance value of the object of testing/(average value Cga of the corresponding measured capacitance values of the good product) is calculated. If Ci<Cgj(1-.DELTA.e0) or Ci>Cgj(1+.DELTA.e0), the measured capacitance values Ci and Cgjare excluded from the objects of calculation of the average values. If Cj<.mu..Cgj(1-.DELTA.e) or Cj>.mu..Cgj(1+.DELTA.e), a wiring j is judged to be defective and the resistance measuring method is employed to judge the details of the defect. The tolerance rate .DELTA.e0 and .DELTA.e are 0.15 and 0.02 respectively.