Method of verifying preamplifier circuit functions, and magnetic record regeneration apparatus using the same

1. A preamplifier circuit of a magnetic record regeneration apparatus with a write system which sends write currents corresponding to write data to a magnetic head performing writing and readout of data into and from a recording medium and a read system which receives readout currents of the magnetic head, comprising, in the write system:

a write driver;

a current-voltage conversion circuit for converting the write current from the write driver into a corresponding voltage;

a waveform shaping circuit for converting the output voltage from the current-voltage conversion circuit into a full-wave rectified waveform;

a peak-hold circuit for holding a peak value of the output from the waveform shaping circuit;

a filter circuit for outputting an average voltage of the output from the waveform shaping circuit; and

a determination circuit for determining that the write driver is abnormal based on each output status of the peak-hold circuit and the filter circuit.

2. The preamplifier circuit of a magnetic record regeneration apparatus of claim 1 ,

wherein the determination circuit determines that the write driver is abnormal when an AND logic does not approved between the outputs of the peak-hold circuit and the filter circuit.

3. The preamplifier circuit of a magnetic record regeneration apparatus of claim 1 ,

wherein the determination circuit has first comparative detection means for outputting an error if the output of the peak-hold circuit deviates from a range relative to a first reference voltage, and second comparative detection means for outputting an error if the average voltage output of the filter circuit deviates from a range relative to a second reference voltage, and

wherein it is determined that the write driver is abnormal when either the first comparative detection means or the second comparative detection means output an error.

4. The preamplifier circuit of a magnetic record regeneration apparatus of claim 1 , further comprising:

a changeover switch provided on the input side of the write driver;

means for converting the write data into an analog signal and returning the write data to the read system when the changeover switch prevents the write data from being input to the write driver; and

a determination circuit for determining whether the read system is normal or abnormal from the returned analog signal, the determination circuit comprising:

a circuit for obtaining an envelope curve of the returned analog signal; and

a comparison circuit for comparing the level of the obtained envelope curve with a predetermined reference value,

wherein it is determined from the comparison in the comparison circuit that the read system is abnormal when the level of the envelope curve is smaller than the reference value.

5. The preamplifier circuit of a magnetic record regeneration apparatus of claim 2 , further comprising:

a changeover switch provided on the input side of the write driver;

means for converting the write data into an analog signal and returning the write data to the read system when the changeover switch prevents the write data from being input to the write driver; and

a determination circuit for determining whether the read system is normal or abnormal from the returned analog signal, the determination circuit comprising:

a circuit for obtaining an envelope curve of the returned analog signal; and

a comparison circuit for comparing the level of the obtained envelope curve with a predetermined reference value,

wherein it is determined from the comparison in the comparison circuit that the read system is abnormal when the level of the envelope curve is smaller than the reference value.

6. The preamplifier circuit of a magnetic record regeneration apparatus of claim 3 , further comprising:

a changeover switch provided on the input side of the write driver;

means for converting the write data into an analog signal and returning the write data to the read system when the changeover switch prevents the write data from being input to the write driver; and

a determination circuit for determining whether the read system is normal or abnormal from the returned analog signal, the determination circuit comprising:

a circuit for obtaining an envelope curve of the returned analog signal; and

a comparison circuit for comparing the level of the obtained envelope curve with a predetermined reference value,

wherein it is determined from the comparison in the comparison circuit that the read system is abnormal when the level of the envelope curve is smaller than the reference value.

7. A magnetic record regeneration apparatus, comprising:

a magnetic head for performing writing and readout of data into and from a recording medium; and

a preamplifier circuit with a write system which sends write currents corresponding to write data to the magnetic head and a read system which receives readout currents of the magnetic head, the preamplifier circuit comprising, in the write system:

a write driver;

a current-voltage conversion circuit for converting the write current from the write driver into a corresponding voltage;

a waveform shaping circuit for converting the output voltage from the current-voltage conversion circuit into a full-wave rectified waveform;

a peak-hold circuit for holding a peak value of the output from the waveform shaping circuit;

a filter circuit for outputting an average voltage of the output from the waveform shaping circuit; and

a determination circuit for determining that the write driver is abnormal based on each output status of the peak-hold circuit and the filter circuit.

8. The magnetic record regeneration apparatus of claim 7 ,

wherein the determination circuit determines that the write driver is abnormal when an AND logic does not approved between the outputs of the peak-hold circuit and the filter circuit.

9. The magnetic record regeneration apparatus of claim 7 ,

wherein the determination circuit includes first comparative detection means for outputting an error if the output of the peak-hold circuit deviates from a range relative to a first reference voltage, and second comparative detection means for outputting an error if the average voltage output of the filter circuit deviates from a range relative to a second reference voltage, and

wherein it is determined that the write driver is abnormal when either the first comparative detection means or the second comparative detection means output an error.

10. The magnetic record regeneration apparatus of claim 7 , wherein the preamplifier is further comprised of:

a changeover switch provided on the input side of the write driver;

means for converting the write data into an analog signal and returning the write data to the read system when the changeover switch prevents the write data from being input to the write driver; and

a determination circuit for determining whether the read system is normal or abnormal from the returned analog signal, the determination circuit comprising:

a circuit for obtaining an envelope curve of the returned analog signal; and

a comparison circuit for comparing the level of the obtained envelope curve with a predetermined reference value,

wherein it is determined from the comparison in the comparison circuit that the read system is abnormal when the level of the envelope curve is smaller than the reference value.

11. A method of verifying normality of a preamplifier circuit in a magnetic record regeneration apparatus having a write system which sends write currents corresponding to write data to a magnetic head performing writing and readout of data into and from a recording medium and a read system which receives readout currents of the magnetic head, the method comprising the steps of:

converting the write current from the write driver in the write system into a corresponding voltage;

converting the converted voltage into a full-wave rectified waveform;

holding a peak value of the converted full-wave rectified waveform;

outputting an average voltage of the converted full-wave rectified waveform; and

determining that the write system is abnormal based on the peak value and the average voltage.