Advertisement
Check and Adjustment of the Head Amplifier Section
Item
1. Head azimuth
1) Play back the end part of the test tape VT703 (10 kHz).
2) Adjust the head azimuth screws so that the output becomes
adjustment
maximum in both the normal and reverse directions. After
adjustment, lock the screws with screw bond without fail.
Measuring output terminal: Speaker terminal, 3 load resistance
Difference between L-ch and R-ch: Within 3 dB
Difference between FWD and REV directions: Within 4 dB
2. Tape speed
1) Play back the end part of the test tape VT712 (3 kHz).
adjustment
2) Adjust VR37 so that the frequency counter reads 3015
in playback in the normal direction.
(Reference value)
Speed difference
Measuring output terminal: Speaker terminal
between the
Make sure that speed difference between the normal and
normal and
reverse directions is 60 Hz or less by reading of the frequency
reverse directions
counter. (With the beginning part of the test tape)
Wow and flutter
Play back the end part of the test tape VT712 (3 kHz).
Make sure that the wow and flutter meter reads 0.25 % (WRMS)
or less.
1) Set a blank cassette tape (Type I: AC225) and enter the set into
3. Recording /
the recording pause mode.
playback
frequency
2) Cancel the pause mode and start recording. Repeat to input the
characteristic
1 kHz and 10 kHz reference signals alternately from the CD test
adjustment
disk to record the signals on the blank tape.
3) While playing back the repeatedly input 1 kHz and 10 kHz
reference signals, adjust VR31 so that output distortion between
the 1 kHz and 10 kHz signals is -1 dB
(Reference value)
1) Set a blank cassette tape (Type I: AC225) and enter the set into
Recording bias
the recording pause mode.
frequency
2) Make sure that the bias frequency at the bias test point on the
head amplifier P.C. board is 70
(Reference value)
1) Set a blank cassette tape (Type I: AC225) and enter the set into
Erasing current
the recording pause mode.
2) After connecting a 1
cancel the pause mode and start recording. Connect the
electronic voltmeter to both the terminals and measure the
erasing current.
Check/Adjustment Method
1 dB.
9 kHz.
resistor to the erasing head in series,
UX-F70MD/UX-F72MD
Standard
Adjusting
Value
Point
Head
Maximum
azimuth
output
screw
15 Hz
3015
VR37
60 Hz or less
0.25 %
(WRMS) or
less
VR31
-1dB
70
Erasing
current: 60
mA (Type I
tape)
15Hz
1dB
9kHz
1-39
Advertisement
