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djustment of the APC (NT%)
Measuring
Frequency counter
instrument
I
Mode
Playback
Tape used
Alignment tape (VROATSV)
(stair-case waveform)
TP504
Test point
Adjusting point
Specification
1. Insert the alignment tape and place,the unit to
the playback mode.
2. Connect the frequency counter to TP504. Adjust
C518 (APC control) so that the counter reading
be 3.579545MHz + 20Hz.
n
ADJUSTMENT OF AUDIO CIRCUIT
Figure 2-13. AUDIO PWB
Measuring
VTVM
instrument
Mode
Playback
Input signal
Alignment tape
(VROATSV)
(1 -kHz level control signal)
Test point
Audio output signal
Adjusting point
R610 (playback level control)
Specification
- 9 t l d B s
1. Play back the alignment tape (I-kHz level control
signal).
2. Hook up the VTVM to the audio output terminal.
3. Adjust R610 (playback level control) so that the
output level be - 9 + 1 dBs.
C h e c k i n g o f e r a s e v o l t a g e a n d o s c i l l a t i o n
frequency
Measuring
Oscilloscope
instrument
Mode
Recording
Input signal
Test point
Adjusting point
Specification
Erase voltage; Over 40 Vp-p
Oscillation frequency; 70 fi 5
1. Place the unit to the record mode.
2. Hook up the oscilloscope to both ends of the full-
erase head.
3. Make sure the erase voltage is over 40 Vp-p.
4 . B e s u r e t h a t t h e o s c i l l a t i o n f r e q u e n c y i s
70 5 5kHz.
Figure 2-14.
Adjustment of bias current
Measuring
VTVM
instrument
Mode
Recording
Input signal
Test point
TP601 (SIG), TP602 (GND)
Adjusting point
R630 (bias current control)
Specification
260 + 1 OuA (2.6mV + 0.1 mV)
1. Place the unit to the record mode.
2. Connect the VTVM to TP601 (SIG) and TP602
(GND).
3. Adjust R630 (bias current control) so that the bias
current be 260 t 1 OyA (2.6 + 0.1 mV).
5 Useddiv
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