Electrical Adjustments - Sony Walkman PCM-M1 Service Manual

14. Move down the TG1 guide (by turning it clockwise), and
confirm that the RF waveform loses parallel shape, then return
the SG1 guide to original position. When the original
waveshape cannot be restored (Fig. 8), repeat steps 5 to 8.
(note) Do not adjust the SG1 and TG1 guides at the same
time.They must be testified and adjusted
independently.)
Be sure to complete adjustment of either one of the
guides, then start adjustment on the other guide.
15. Confirm that the waveform during the FWD mode is obtained
in the following modes.
Confirm also that the waveform in the FF/REW mode conforms
to the waveform shown in Fig. 9.
FWD STOP FWD
STOP FF FWD
EJECT FWD
• Confirmation of torque
Preparation:
Remove the cassette lid from the holder.
[ 1 FWD mode]
1. Establish a test mode.
2. Select and set a test mode code 40.
3. Insert a torque meter TW-7131.
4. Establish the 1 FWD mode by pressing the VOLUME key.
5. Observe and confirm the torque meter reading.
FWD takeup torque: 5 to 9 g•cm
FWD back tension: 3 to 6.5 g•cm
[ 1 REV mode]
1. Establish a test mode.
2. Select and set a test mode code 40.
3. Insert a torque meter TW-7131.
4. Establish the 1 REV mode by pressing the VOLUME key.
5. Observe and confirm the torque meter reading.
REV takeup torque: 5.5 to 8.5 g•cm
REV back tension: 11.5 to 17 g•cm
• Confirmation of T-reel lock
1. Enter the test mode.
2. Set the test mode code to 32 using the MODE key. Then press
the ENTER key.
3. Find the tape of a 120-minute tape. Insert the tape to the
machine.
4. Press the STOP key. Confirm that any number of either 0, 1, 2,
3 or 4 appears in the display window when the EJECT key is
pressed.
If a number of 5 or higher appears, replace the Limiter (F reel)
Assy (X-3373-741-1) and check the T-reel lock again.
CUE FWD REV FWD
STOP REW FWD STOP
• Confirmation of speed
[Capstan FG]
1. Connect a frequency counter to TP508 (CFG).
2. Establish a test mode.
3. Select and set the test mode code 40.
4. Insert a test tape TY-30B.
5. Establish the 0.5 FWD then 1 FWD modes by pressing the
VOLUME key and take reading of frequency counter
respectively.
Mode
0.5FWD
1FWD
[Drum FG]
1. Connect a frequency counter to TP507 (DFG).
2. Establish a test mode.
3. Select and set the test mode code 40.
4. Insert a test tape TY-30B.
5. Establish the 0.5 FWD then 1 FWD modes by pressing the
VOLUME key and take reading of frequency counter
respectively.
Mode
0.5FWD
1FWD

3-3. ELECTRICAL ADJUSTMENTS

• Voltage check
1. Establish a test mode.
2. Select and set the test mode code 40.
3. Measure DC voltage at the respective test points using VOM
and confirm that the DC voltages satisfy the specifications.
Test point
REG3.5V (TP602)
3.5V (TP605)
MIC L (TP101)
MIC R (TP201)
• Switching pulse (SWP) adjustment
Note: Be sure to perform the tape pass adjustment when rotary
drum is replaced.
Preparation: Oscilloscope
– 24 –
Frequency
311Hz 5Hz
622Hz 5Hz
Frequency
400Hz 1Hz
800Hz 1Hz
Specifications
3.5V
3.5V
1.9V 0.3V
1.9V 0.3V
Frequency band width:
100 MHz or more
CH-1: AC 100 mV/DIV
CH-2: AC 2 V/DIV
0.2 msec/DIV
TRIG:CH-2