Electrical Adjustments (Vcr); Adjustment Procedure - Aiwa VX-T147 Service Manual

(VCR SECTION)

3. ADJUSTMENT PROCEDURE

Read and perform these adjustments when repairing
the circuits or replacing electrical parts or PCB assemblies.
CAUTION
When replacing IC's or transistors, use a silicon grease.
(To prevent the damage to IC's and transistors.)
3-1: PG SHIFTER (HEAD SWITCHING) ADJUSTMENT
CONDITIONS
MODE-PLAYBACK
Input Signal-Alignment Tape (JG001C) or Similar
INSTRUCTIONS
1. Unplug the AC plug for more than 30 minutes to set the
clock to the non-setting state. (To release the Back-Up
immediately, take the short circuit between C101 and
GND at the Power Off.) Then, set the volume level to
minimum.
2. Connect CH-1 on the oscilloscope to TP4001 and CH-2
to TP4501.
3. Playback the alignment tape. (JG001C)
4. Press and hold the Tracking Auto button more than 2
seconds to set the tracking to center position.
5. Press the VOL. DOWN button on the set and the
channel button (3) on the remote control simultaneously
until the indicator REC disappears. If the indicator REC
disappears, adjustment is completed.
(If the above adjustments doesn't work well:)
6. Press the VOL. DOWN button on the set and the
channel button (3) on the remote control simultaneously
until the indicator REC disappears.
7. When the REC indicator is blinking, press both VOL.
DOWN key on the set and the channel button (4) on the
remote control simultaneously and adjust the Tracking
+/- button until the arising to the down of the Head
Switching Pulse becomes 6.5 ± 0.5H.
8. Press the Tracking Auto button.
ELECTRICAL ADJUSTMENTS
CH-2
6.5H
CH-1
Fig. 3-1-A
CH-2
CH-1
6.5H
Fig. 3-1-B
3-2: VCO COIL
NOTE
For adjusting of VCO, connect input and output terminals
of sweepmarker generator to the circuit as shown below,
then adjust it.
Sweepmarker
Generator
Output
Input
CONDITION
MODE-STOP
INSTRUCTIONS
1. Connect the output of sweepmarker generator to pin 5
of IC6001.
2. Connect the input of sweepmarker generator to pin 17
of IC6001.
3. Connect a 10K ohm variable resistor to IF AGC terminal
(pin 4 of IC6001), 9V line and ground, then adjust to
make the waveform of the oscilloscope readable.
4. Adjust L6011 until the waveform marker (39.5MHz)
becomes as shown in Fig. 3-2.
3-3: AFT COIL
CONDITION
MODE-STOP
INSTRUCTIONS
1. Connect the output of sweepmarker generator to pin 5
of IC6001.
2. Connect the input of sweepmarker generator to pin 3 of
CP6115.
3. Adjust L6012 until the waveform marker (39.5MHz)
becomes as shown in Fig. 3-3.
4. Disconnect the sweepmarker generator and the
oscilloscope.
5. Connect the generator (39.5MHz) to the pin 4 of
CP6115 through 2.2K ohm and connect the DC
voltmeter to pin 3 of CP6115.
6. Adjust L6012 until the DC voltage at pin 3 of CP6115 is
3.8V ± 0.1V.
D2-2
0.022µF
75K
47K IN60 45PF
IN60
100PF
39.5MHz
TP
GND
TP
GND
Fig. 3-2