Teac A-650 - Recording Performance Adjustments (Continued); Record Bias Setting for Various Tapes

6-4-2. RECORD BIAS SETTING
Preparations:
Connection: See Fig. 6-11 on page 25.
Switch Setting:
3.
DOLBY NR
BIAS
EQ
LIMITER
4.
OUT
OUT
OUT
1
1
5.
6.
7.
7 kHz,
400Hz
OPTIMUM VALUE
BIAS CURRENT ---- =►
7 kHz
4dB
400 Hz
REQUIRED VALUE
BIAS CURRENT
T- 509
Bias Adjustment (Hi-Fi tape)
Fig. 6-14
26
Load a TEAC MTT-505B test tape.
Adjust VC602/601 in a counter clockwise direction
until the capacitor leaf springs open completely.
Apply and record two tone signals in turn; a 1 kHz
signal and a 7 kHz signal, both at — 42 dB (6.15 mV).
Rewind and play this recorded section and note the
VTVM indication.
Turn VC602/601 clockwise slightly and record another
section of tape.
Rewind over this section and play the tape again and
note the VTVM indication.
Repeat this operation of recording, rewinding, playing,
and adjusting until no difference in playback level
between these two signals is obtained.
LINE:
MIC:
O
Ld
CO
Z
o
Q.
CO
UJ
or
g
3
O
LxJ
CO
z
o
co
UJ
or
Hi-Fi TAPE
18. Load a TEAC MTT-501 test tape with the BIAS/EQ
switches set to the “ 3 ” position and with the DOLBY
NR IN-OUT-IN/MPX switch set to IN.
19. Apply and record 2 tone signals, in turn; a 400 Hz tone
at -39 dB (8.69 mV) and a 10 kHz tone at -39 dB.
20. Rewind and play this recorded section.
21. Compare the differences between the output level of
the 400 Hz signal and that of the 10 kHz signal.
22. The output level of the 10 kHz signal must be 4 dB
above the 400 Hz signal level.
23. Adjust VC606/605 to achieve this, continuing the
process of recording-rewinding-playing-adjusting.
Control Setting:
OUTPUT: Specified Setting (See 6-2-2)
Specified Setting (See 6-3-2)
Minimum Setting
CrO 2 TAPE
1.
2.
Fe-Cr TAPE
8. Set BIAS/EQ switches to position #2.
9. Load MTT-501 test tape.
10. Adjust VC604/603 counter clockwise until capacitor
leaf springs open completely.
11. Connect a 1 kHz, -15 dB input signal.
12. Record a ten second section of tape, rewind and play
that section and note VTVM indication.
13. Adjust VC604/603 slightly clockwise.
14. Repeat this operation of recording, rewinding, playing,
and adjusting until the peak value on the VTVM is
obtained.
15. After the preceding adjustment is done, install the
MTT-504 tape.
16. Apply and record two tone signals alternately, a 1 kHz
signal and a 7 kHz signal, both at -42 dB (6.15 mV).
17. Further adjust VC604/603 slightly until identical read 
ings at both frequencies are found using the process of
adjusting, recording rewinding and playing back the
tape.
T-580
Fig. 6-13 Bias Adjustment (CrOj & Fe-Cr tape)