Sharp RT-100H Serviceanleitung Seite 8

BIAS CURRENT AND
ENCY ADJUSTMENT OF RECORD AMPLIAER
(See Figure 8-1 )
1. Connect electronic voltmeter, across axesistor R102 (or
R202), between the test point TPIOI
ground.
Cdnnecf•än oscilloscope and a frequency counter to the
2.
outpåt terminalsof electronicvoltmeter.
3. There are two tape selector switches: one is SW4 named a
naméd a metal 'tape ON/OFF •switch. To allow the unit to
play a normal tape, set SW4 at NORMAL position and SW5
at OFF position, respectively.
Place the unit in record mode,
4.
Adjust bias oscillation
5.
frequeqcy becomes 105 kHz.
SetmetaltapeON/OFFswitch SW5 to ON position,
6.
7. Adjust semi-yariableresistorSVR301. (and VR302) so that
the electronic voltmeter
8.
lhen, change metel tape ON/OFF
position.
g.
Seethat the electronicvoltmeterreading varie$• ast?bulated
Table 8-1, as normal/Cr02
changesits position [NORMAL or Cr02 ] ,
SW4
Tape in use
NORMAL NORMAL
cr02 cr02
RECORD 'AMPLIFIER ERASE
(See Figure 8-2 and Table 8-2)
I. Connect electronic voltmeter,
between the test point
2. Set.metal tape ON/OFF switch SW5 to ON position.
Note:
If this switch SW5 is set ON once, it overcomes the function of
NORMAL/Cr02 tape selector switch SW4 whichever position
it may beset at.
3. Place the unit in record mode, and see that the electronic
voltmeter is reading as follows.
Tape SW4
METAL
RECORD/PLAYBACK HEAD
(See Figure 8-3)
1. Connect electronic voltmeter between the test point TPI 03
(or TP203) and ground.
2. To allow the unit to play a normal tape, set NORMAL/
Cr02 tape selector switch SW4 at NORMAL position and
metal tape ON/OFF •switch,SW5at OFF pöSition.
Also set Dolby NR switch SW3 at OFF position.
3. Put a test tape (TEAC,MTT—114, 1 0kHz,250pWb/mm,
—IOdB recorded) into the unit and play it back.
4. Adjust the head azimuth adjusting screw so that the
electronic voltmeter reaches its maximum
phase difference between the channels.
Note:
It is now recommendableto usean oscilloscopeto-check that
there will be the samephasefor the right and left channels.
ELECTRICAL
BIAS OSCILLATION
(or TP201) and
coil L303 so that the bias oscillation
reads 93mV to 110mV.
switch SW5 to OFF
tape selector switch SW4
SW5
Voltmeter
OFF 45mV
OFF 63mV to 76mV
Table 8-1
VOLTAGE CHECK
across a resistor
TP301 and ground.
SW5
Voltmeter
ON 180mV to 250mV
Table 8-2
AZIMUTH ADJUSTMENT
reading, with no
ADJUSTMENT
FREQU-
PLAYBÄCK FREQUENCY CHARACTERISTIC CHECK
(See Figure 8-4)
I. Connect electronic voltmeter between thé test point TP102
(or TP202 ) and ground.
To allow the unjt to play a normal tape,.set NORMAL/
2.
Cr02 tape selectorswitch SW4at NORMALpositionand
metal t ape ON/OFF switch SW5 atOFF po$tiqn.
Also set Dolby NR switch SW3 at OFF position.
3. Put test tape (TEAC MTT-217Er
is SWS
2SÖpWbiF•nin, —iÖdB,-recorded)—
playback frequency characteristic— into the unit, and play
it båék.
Seé that the electroniC voltmeter is showingthe deviation
4.
of two different input signals•(63Hzand 10kHz) againstthe
1kHz input, as tabulaied Table 8-3.
Frequency
With 63Hz' input
With 10kHz input
reads
G t"id
R301
reads
Tet
usefui for the check of
Deviation against 1kHz input
shown by electronic
NORMAL'
—3dB to +5dB
-5dB to +4dB
Table 8-3
Electronic
Voltmeter
TP10i,TP201
Figure 8-1
Electronic
voltmeter
-TP'OI
8-2
Electronic
voltmeter
Meda i, "203
Grau
R • cod/
Record/PIayback
Figure 8-3
Electropiq
voltmetør
1
Mod.
G ram d
Had
Figure 8-4
voltmeter
cr02
—3dB to +5dB
-9dB to OdB
Head
O•ell oscape'