HCD-GPX6/GPX7
21
21
SECTION 5
ELECTRICAL ADJUSTMENTS
DECK SECTION
1. Demagnetize the record/playback head with a head
demagnetizer.
2. Do not use a magnetized screwdriver for the adjustments.
3. After the adjustments, apply suitable locking compound to the
parts adjust.
4. The adjustments should be performed with the rated power
supply voltage unless otherwise noted.
5. The adjustments should be performed for both L-CH and R-
CH.
6. Switches and controls should be set as follows unless other-
wise specified.
REC BAIS ADJUSTMENT
Setting:
Procedure:
1.
Connect a digital voltmeter (AC range) to TP101 (L), TP201
(R) and TP (GND) on the MAIN board.
2.
Insert a tape.
3.
Press the
I
/
1
button to turn the power on, and press the
[FUNCTION]
button to select TAPE function.
4.
Press the
[ REC]
button twice to start recording.
5.
Adjust RV101 (L-ch), RV201 (R-ch) on the MAIN board so
that the digital voltmeter reads AC 6.15 V.
6.
Connect an oscilloscope or frequency counter to TP101 (L),
TP201 (R) and TP (GND) on the MAIN board.
7.
Confirm that the frequency is 82 kHz
±
3 kHz.
Adjustment Location:
MAIN board
digital voltmeter
(AC range)
TP101 (L), TP201 (R)
TP (GND)
– MAIN BOARD (Conductor Side) –
RV201
RV101
TP (GND)
REC BIAS ADJUSTMENT
(R-CH)
(L-CH)
TP201 (R)
TP101 (L)
CD SECTION
Note:
1.
CD Block is basically designed to operate without adjustment. Therefore,
check each item in order given.
2.
Use YEDS-18 (3-702-101-01) unless otherwise indicated.
3.
Use an oscilloscope with more than 10M
Ω
impedance.
4.
Clean the object lens by an applicator with neutral detergent when the
signal level is low than specified value with the following checks.
S-CURVE CHECK
Procedure :
1. Connect an oscilloscope to TP (FE) and TP (VC) on the CD
board.
2. Press the
I/
1
button to turn the power ON.
3. Load a disc (YEDS-18) and actuate the focus search. (In
consequence of open and close the disc tray, actuate the focus
search)
4. Confirm that the oscilloscope waveform (S-curve) is
symmetrical between A and B. And confirm peak to peak level
within 2.0
±
0.5 Vp-p.
Note:
•
Try to measure several times to make sure than the ratio
of A : B or B : A is more than 10 : 7.
•
Take sweep time as long as possible and light up the
brightness to obtain best waveform.
Connecting Location: CD board
RFAC LEVEL CHECK
Procedure :
1. Connect an oscilloscope to TP (RFACO) and TP (VC) on the
CD board.
2. Press the
I/
1
button to turn the power ON.
3. Load a disc (YEDS-18) and playback.
4. Confirm that oscilloscope waveform is clear and check if RFAC
signal level is correct or not.
Note:
Clear RFAC signal waveform means that the shape “
◊
” can be
clearly distinguished at the center of the waveform.
Connecting Location: CD board
CD board
Oscilloscope
TP(FE)
TP(VC)
symmetry
S-curve waveform
within 2.0
±
0.5 Vp-p
A
B
TP(RFACO)
CD board
oscilloscope
TP(VC)
RF signal waveform
VOLT/DIV : 200mV
TIME/DIV : 500ns
level : 0.7
±
0.3 Vp-p
– CD BOARD (Conductor Side) –
TP
(VC)
TP
(FE)
TP
(RFACO)
IC101
z
