Sharp VC-MH80 Service Manual page 41

Hi-Fi -AUDIO CIRCUIT-ADJUSTMENT
IMPORTANT NOTES ON Hi-Fi SECTION
1. Though adjustment procedures are written for
the left channel, those for the right channel are
basically the same.
-Words shown in the bracket " [
right channel only.
2. SERVICING OF THE Hi-Fi block
1) " RECORD MODE"
Under this condition record a stereo broadcast
on tape and adjust control.
2) " PLAYBACK MODE"
Under this condition, play a-Hi-Fi tape and
adjust control.
(You can select the audio output channels in
the playback mode by pressing the MENU on
the remoto control or the SET UP button on
pressing the (+) or (-) button.
The Audio Output mode will change in the
normally select Hi-Fi L+ R mode with the
pressing the ( +) or (-) button both the L and
mode track. The L and R indicators light up on
the multi-function display in this mode.)
CHECKING OF E-E LEVEL
Measuring AC milli-voltmeter
instrument
Mode E-E or Recording mode
Input signal 1 kHz, - 8dBs
Test point
Specification
1. Feed the audio signal shown in table to the left
channel of the AUDIO IN jack.
2. Connect an AC milli-voltmeter to left channel of
the AUDIO OUT jack and right channel of the
AUDIO OUT jack.
3. Put the unit in E-E or recording mode with the
m a k e s u r e t h a t t h e milli-voltmeter
specified value.
(Check the level is less than 2dB both Left
channel and Right channels.)
ADJUSTMENT
Measuring
instrument
Mode
Input signal
Test point
Controls
Specification
1. Put the unit in A/V input mode. Do not feed any
signal to the VIDEO IN JACK.
( D i s c o n n e c t a n y c a b l e f r o m v i d e o i n p u t
terminal.)
2. Put the unit in E-E or recording mode and
connect a frequency counter to test points
3. Put the unit in NTSC mode with the adjust R6310
the counter reads specified value:
4. In the next place put the unit in PAL mode with
the adjust R6308 [R6365] (PAL carrier frequency
control) so that the counter reads specified
value.
ADJUSTMENT OF LINEAR AUDIO BIAS
CURRENT
Measuring
instrument
Mode
Input signal
Test point
Control
r e a d s
Specification
1. Connect the oscilloscope to test points TP6303
(GND) and TP6304 (Sig.).
(Use TP6304 for ground lead.)
2. Put the unit in recording mode with the adjust
R6343 so that the signal amplitude is 2.5mVrms.
41
OF
FM CARRIER FREQUENCY
Frequency counter
E-E or REC mode
Not required
R6310 [R6363] NTSC carrier
frequency control
R6308 [R63651 PAL carrier
frequency control
1.3 [ 1.7] MHz ? 5kHz (at NTSC
mode)
1.4 [1.8] MHz + 5kHz (at PAL
Oscilloscope
Record
Not required
TP6303 (GND) - TP6304 (Sig.)
R6343 Bias current control
2.5 + 0.1 mVrms
VC-MH80