Sony TC-366 - Record Bias Adjustment

(7) Turn the zenith adjusting screw by the same
angle of turns of the height adjusting screw
obtained in preceding procedure (6).
(8) After the adjustment, check the tape pass
adjustment again.
tape blank
AF
OSC REC Amp
OEE
azimuth: AUX 15kHz, -40d0B
track position: AUX (R) 1kHz, -10dB
LINE OUT
Record head azimuth and track
position adjustment setup
12-11. Record Head Phase Check
Fig. 12-15
Connection:
As shown in Fig. 12-16.
Switch Setting:
MONITOR switch......... TAPE
VR Setting:
AUX VOLUME.............. indicated on page 25
Procedures:
(1) Make the p.b. head phase check.
(2) Thread a blank tape.
(3) Deliver a 1.5 kHz signal of -10 dB (0.24V)
into the AUX INput jack and record the
signal on the blank tape.
(4) Be sure to obtain the Lissajous figure as
shown in Fig. 12-17.
oscilloscope
L — REC Amp.
tape, blank
AF
osc
AUX
1.5 kHz, -10 dB
LINE OUT
Fig. 12-16 Record head phase check setup
Phase difference
Ye
OW
no
difference
within
30°
more
than
30°
reverse
e
than
30"
“feverse:
Blase
good
wrong
Fig. 12-17 Lissajous figures
VTVM
12-12. Record Bias Adjustment
Connection:
As shown in Fig. 12-19.
Adjusting Parts:
C128 (C228) oo. ee eer See Fig. 12-2
Switch Setting:
MONITOR éwitth sieissndcaen, TAPE
TAPE SPEED switch ............. 19cm/s (7% ips)
VR Setting:
AUX and MIC VOLUME
Sedat etn Set, indicated on page 25
Procedures:
(1) Be sure that the trap coil adjustment has
been made.
(2) Thread a blank tape.
(3) Deliver a 1 kHz signal of -10dB (0.245V)
into the AUX INput jack.
(4) While recording the signal on the blank tape,
turn the trimmer capacitor C128 (C228)
clockwise slowly until the VTVM reads the
maximum value.
(5) Continue to turn the trimmer capacitor until
the VTVM reads a value 0.5 dB below the
maximum reading.
(6) Disconnect the VITVM and connect it across
the record head.
(7) Be sure that the VTVM reading is approxi-
mately 14V.
(8) Be sure that the VITVM reading decreases
by degrees, as the TAPE SPEED switch is
changed to 9.5cm/s and then 4.8cm/s.
(9) After the adjustment, apply lock paint to
the capacitors.
0.5dB
LINE OUT
level
ie 5c ee
bias level
counterclockwise ~q————-——-w=-_ clockwise
Fig. 12-18 Record bias characteristics