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Means for Testing Direct Access Storage Device (DASD) Actuator Voice Coils

IP.com Disclosure Number: IPCOM000119443D
Original Publication Date: 1991-Jan-01
Included in the Prior Art Database: 2005-Apr-01
Document File: 1 page(s) / 44K

Publishing Venue

IBM

Related People

Siverling, MM: AUTHOR

Abstract

Described is a solution for problems when testing the voice coils for a high density magnetic disk drive actuator assembly. This method solves the following: It can determine if the coil is open circuited, wired with its leads reversed, has a short in its wiring, has too few or too many turns, or if the coil is shorted to the actuator body. This method does all this very expediently and accurately in one test. (See the figure.) The components to do it are readily available.

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Means for Testing Direct Access Storage Device (DASD) Actuator Voice
Coils

      Described is a solution for problems when testing the voice
coils for a high density magnetic disk drive actuator assembly.  This
method solves the following:  It can determine if the coil is open
circuited, wired with its leads reversed, has a short in its wiring,
has too few or too many turns, or if the coil is shorted to the
actuator body.  This method does all this very expediently and
accurately in one test.  (See the figure.)  The components to do it
are readily available.

      The method is to place a common precision inductor physically
so that it has high mutual coupling with the voice coil to be tested.
The two are then wired together so as to form an auto transformer.
The input A.C. signal is chosen to maximize the correlation of the
test result to the application.  The output is amplitude or peak
detected - A. to D.'d and presented to the computer doing the test.
If the coil is open or shorted, the output is diminished according to
the impedance of the defect.  If the coil leads are reversed and it
is phased wrong, the mutual inductance will have the wrong sign in
the equation for the output, and of course, an out-of-specification
reading is obtained in the test.  Too few or too many turns is
detected by using the equation of input multiplied by the transformer
turns ratio to obtain the output voltage.  Given that the actuator
body is at a different potential than...