Checking Of Audio (Low Frequency) Circuit - Sharp GF-500 Service Manual

BIAS OSCILLATOR FREQUENCY CHECK
1. Make connection of instruments as shown in Fig. IO-l.
2. Set the function selector switch to "tape" and the beat
cancel switch to " A" .
3 . P l a c e t h e u n i t i n r e c o r d m o d e , a n d c h e c k t h a t t h e
frequency counter reads 90 +5kHz.
Changing the beat cancel switch from " A" to " 6" position,
see that the frequency counter reading changes by +4 -
cancel switch set at " C" position, see that it changes by -3
P L A Y B A C K A M P L I F I E R S E N S I T I V I T Y C H E C K
1. Make connection of instruments as shown in Fig. 10-2.
2. Set the function selector switch to "tape", the volume
control knob to " lO/max" , and the treble/bass tone control
knob to " center" position.
3. Play a test tape (TEAC, M T T - 1 1 8 , IkHz, 250pWb/mm,
4. See that the electronic voltmeter reads about 1.8V.
R E C O R D AMPLIFIER SENSITIVITY CHECK
2. Check for the input voltage available when the level
indicator " OVU" lights up. See Table 10.
For the radio (high frequency) Circuit adjustment, refer to the GF-54542 Service Manual
Record Mode
Figure IO-I
Test Tape
MTT-118
Head
Figure IO-2
Phono input
Line input
External mic input
Table IO
Oscilloscope
1.99 - 3.9mV
( - 5 0 ?3dB, OdB = I V )
39.8 - 79mV
( - 2 5 ?3dB, OdB = I V )
1.58 m 3.16mV
( - 5 3 +3dB, OdB = 1V)