Teac A-300 - Electrical Checks and Adjustments (Continued); Input Level Checks and Recording Performance Notes

4, Apply a 400 Hz signal at —19 dB (86.9 mV) to the
LINE IN jacks and check for -2.5 dB + 3 dB (411 mV
to 818 mV).
5. Then if the level difference between channels is more
than 2 dB, adjust R22 so that the level difference
become less than 2 dB between channels. (Minimum
Input Level checks for the LINE inputs).
6. Set the LINE controls to minimum and the MIC
controls to maximum.
7. Apply a 400 Hz signal at —67 dB (346 yV) to the MIC
jacks and check for 2.5 dB + 3 dB. (Minimum Input
Level checks for the MIC jack).
8. Remove the MIC input and apply a 400 Hz signal at
~—35 dB (13.8 mV) to the input terminals of the DIN
connector and check for —2.5 dB + 3 dB.
(Minimum Input Level checks for the DIN inputs).
9, For the following test, set the MIC controls to mini-
mum, remove the DIN connector and then connect
input signal to the LINE IN jacks.
6-3. RECORDING PERFORMANCE
NOTE: 1. Before marking any adjustments of the record-
ing circuit, be sure that the tests in the preceding
performance sections have been accomplished.
The preceding performance should be properly
adjusted, otherwise record calibration will be
inaccurate.
2. The adjustments and checks for NORMAL tape
usually may be omitted unless the technician
wishes to confirm that they also are within
specifications except for the sections where
these tape are designated.
6-3-1. BIAS TRAP ADJUSTMENTS
NOTE: The AC Voltmeter used in this procedure must
have load impedance of 1M ohm or more.
1. Connect the AC Voltmeter to the BIAS TRAP test
point.
Load any recordable tape.
3. Place the deck in the REC PAUSE mode with no signal
applied.
4. Adjust L103/L203 for a minimum reading.
nN
14
6-2-2. SPECIFIED LINE CONTROL SETTING
Specification: Specified input level: —9 dB (275 mV)
10. Apply a 400 Hz signal at —9 dB (275 mV) to the LINE
IN jacks.
11. Set the LINE controls to obtain the reading of 580 mV
(—2.5 dB) on the AC Voltmeter. Then check that
OUTPUT level on the deck is —5 dB + 1 dB 388mV
to 489 mV). At this time, the physical position of the
LINE controls indicates the Specified LINE Control
Setting referred to in subsequent procedures.
NOTE: After this setting is done, do not disturb the Speci-
fied Control Setting of the LINE controls until
the remaining checks and adjustments are com-
pleted.
6-2-3. VU METER CALIBRATION CHECKS
Specification: +3 VUt 1 VU
12. Make certain that indication on the VU Meter on the
deck is +3 VU+1 VU.
Preparations:
AC Voltmeter
Tpd LI03/L203
Q106/0206
Fig. 6-9 Connection
Switch Setting:
Pee ee eed
Control Setting:
OUTPUT: Specified Setting (See 6-1-2)
MIC, LINE: Minimum