Teac A-300 - Electrical Checks and Adjustments (Continued); Output Level, VU Meter, and Playback Frequency Response

6-1-2. SPECIFIED OUTPUT LEVEL SETTING
Specifications:
Specified output level: —5 dB (436 mV)
Maximum output level: —2.5 dB +2 dB (461 mV to
731 mV)
1. Lodand play a TEAC MTT-150 test tape.
Adjust R10/R20 for 580 mV (—2.5 dB) on AC Volt-
meter connected to the Dolby test points. (Fig. 6-4)
3. Change the AC Voltmeter connection to the OUTPUT
jacks as shown in Fig. 6-5.
4. Set the OUTPUT controls to maximum and confirm
that —2.5 dB +t 2 dB (461 mV to 731 mV) is obtained
at OUTPUT jacks.
5, Set OUTPUT controls again for —5 dB (436 mV) speci-
fied level.
The position of the OUTPUT controls will now be set
to the specified output level setting. Do not change the
setting of these controls for the remainder of this pro-
cedure unless otherwise indicated.
6-1-3. VU METER CALIBRATION
Specification: +3 VU
6. With the specified setting in paragraph 6-1-2, play the
MTT-150 test tape and adjust R70/R80 for +3 VU
indication on the VU Meters.
6-1-4. FREQUENCY RESPONSE —-PLAYBACK—
7. Load and play the MTT-316 test tape.
8. Play the 315 Hz section of the test tape to get a refer-
ence level on the AC Voltmeter. Then play the re-
quired test signals for comparison with the playback
Frequency Response Limits chart. (Fig. 6-6)
9. Adjust R11/R21 so that the readings obtained on the
AC Voltmeter will be within the response limits.
NOTE: If the response does not meet the specified re-
sponse limits, the head should be checked for
accumulated oxide or dirt. Then, if no dirt is
found, the head azimuth should be readjusted.
12
Preparations:
DECK under TEST
Fig.6-4 Connection
Switch Setting:
Pp [eon [our [Tare
Control Setting:
OUTPUT:
Set for convenient output level.
MIC, LINE: Minimum
ee
OSCILLOSCOPE
under TEST
Fig. 6-5 Connection
t +4
H TEST TAPE: MTT-316 (CrO, )
Lh 44 4
+
3
+
n
2
+
RESPONSE IN 45
%
=f
| -5
in ie |
405063 100125 315 500 1K 2K 4K SK6.3K 10K BOK
FREQUENCY iN Hz
Fig. 6-6 Playback Frequency Response Limits