6-5 Peak Level Meter Adjustments; 6-5-1 Peak Level Meter Calibration; Record; Playback - Teac C-1 Service Manual

10.
11.
$2:
13.
OSCILLOSCOPE
OSCILLATOR O
@®®
AC Voltmeter
DECK
under TEST
oureuT
1%
T~1367
Fig. 6-9 Connection
Set the RECORD controls to obtain a reading of —5 dB
(436 mV) on the AC voltmeter.
Change the AC voltmeter connection to test point | on
the DOLBY ENCODER, of both L- and R-channels, and
set the NR SYSTEM switch to the DOLBY position.
Check that the level at test points is within —2.5 dB +0.5
dB (548 mV to 615 mV).
The determined physical position of the RECORD
controls thus set indicates the specified RECORD control
setting referred to in subsequent procedures.
IMPORTANT: After this setting has been made, do not
disturb the specified control setting of
the RECORD control until the remaining
checks and adjustments are completed.
6-5 PEAK LEVEL METER ADJUSTMENTS
6-5-1 PEAK LEVEL METER CALIBRATION
(INDICATION AND LINEARITY)
— RECORD —
. With the conditions given in paragraph 6-4-2, adjust R867/
R868 so that the meters indicate O dB.
. Change the input level to —39 dB (8.69 mV) and adjust
R869/R870 so that meters indicate —30 dB.
. Repeat these two adjustments until the following re-
querements are obtained.
. Set the input levels and check that the linearity at 0,
10, —20, —30 and —40 dB points on the meter scale
are within the following limits for each level range.
—5 dB to +5 dB=+1 dB
—20 dB to -6 dB + 2.5 dB
—21 dB and over = +3.0 dB
6-5-2 PEAK LEVEL METER CALIBRATION
— PLAYBACK —
Specification: 0 dB ( OO )
5.
6.
7,
Load and play a TEAC MTT-150 test tape.
and confirm that the meter also reads 0 dB.
6-6 RECORDING PERFORMANCE
NOTE: Before making any adjustments of the recording
circuit, be sure that all tests in the above perform-
ance sections have been accomplished. PLAYBACK
and MONITOR performance must be properly
adjusted, otherwise record calibration will be in-
accurate.
6-6-1 BIAS TRAP ADJUSTMENTS
AC Voltmeter
TP 2(R-ch)
gre 1 ON OSC PCB
t
Fig. 6-10 Bias trap adjustment setup
T.P3(L-ch) ON OSC PCB
ves
RECORD
7 HEAD
17-1489
NOTE: The AC voltmeter used in this procedure must have
input impedance of 1M ohm or more.
1. Load a blank tape.
2. Place the deck in the RECORD-PAUSE mode with no
signal applied.