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Fisher 4025 Service Manual

Fisher 4025
12 pages
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Fisher 4025 Specifications

General IconGeneral
Tuning RangeFM, MW
Frequency Response20Hz to 20kHz
Input Sensitivity2.5mV (MM), 150mV (line)
Speaker Impedance8Ω to 16Ω
Signal to noise ratio70dB (line)
Semiconductors13 diodes

Summary

Required Test Equipment

Harmonic Distortion Check

Tuner Alignment

IF ALIGNMENT

Aligns FM IF circuit to center of ceramic filter bandpass.

PRELIMINARY DETECTOR ALIGNMENT

Adjusts generator output for proper detector curve shape.

FRONT END ALIGNMENT

Adjusts FM RF generator for maximum gain and symmetry.

FINAL DETECTOR ALIGNMENT

Adjusts detector alignment for zero point and minimum distortion.

FM OUTPUT

Adjusts VR1 for specified output level.

SIGNAL STRENGTH (0-5) METER ADJUSTMENT

Adjusts VR5 for front panel meter reading.

CENTER CHANNEL METER ADJUSTMENT (4060 only)

Adjusts meter needle for center channel indication.

MUTING LEVEL ADJUSTMENT

Adjusts VR6 to control muting threshold.

STEREO SEPARATION

Adjusts controls for maximum stereo separation.

AM IF

Adjusts T8 for maximum gain.

AM RF

Adjusts L8 (AM Osc) for maximum.

AM OUTPUT

Adjusts VR3 for specified output voltage.

AM SIGNAL STRENGTH METER ADJUSTMENT

Adjusts VR4 to set signal meter reading.

Chassis Parts List

Tuner Schematic (AII Models)

4060/674/895 Schematic

4020/4025/474/495 Schematic

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