Teac A-650 - Monitor Performance Testing; Minimum Input Level Checks; Specified Line Control Setting; Record VU Meter Calibration

6-3. MONITOR PERFORMANCE
6 3-1. MINIMUM INPUT LEVEL CHECKS
Preparations;
OSCILLATO R
1.
Switch Setting:
DOLBY NR
EQ
LIMITER
BIAS
OUT
IN
5.
6.
6-3-4. LED PEAK LEVEL INDICATOR CALIBRATION
6-3-2. SPECIFIED LINE CONTROL SETTING
9.
IM8mV) -6
(SOemvl -s
O-(2Mmv> -9
6-3-3. VU METER CALIBRATION -RECORD-
Specification. +3 VU ( CO)
LED Peak Level Indicator Setting
Fig. 6-1 0
11. Adjust VR 104/204 for +3 VU ( CD ) on the VU meter.
24
3.
4.
Specification:
Specified input level. — 9 dB (274 mV)
7.
8.
Apply a 400 Hz signal at — 9 dB (274 mV) to the LINE
IN jacks.
10. Set the LINE controls to obtain a reading of 580 mV
(-2.5 dB) on the VTVM. At this time, the physical
position of the LINE controls indicates the Specified
LINE Control Setting referred to in subsequent pro 
cedures.
Load any recordable tape.
Place the deck in the RECORD-PAUSE mode.
Set the MIC controls to maximum
Apply a 400 Hz signal at -67 dB ± 2 dB (274 pV ~-
435 pV) to the MIC jacks and check for 580 mV ( — 2.5
dB) on the VTVM connected to the CAL test points.
(Minimum Input Level checks for the MIC jack).
Apply a 400 Hz signal at -35 dB ± 2 dB (10.9 mV ~
17.3 mV) to the input terminals of the DIN connector
and check for 580 mV. (Minimum Input Level checks
for the DIN inputs).
After checking, reduce the MIC controls to minimum
to prevent noise insertion during subsequent pro 
cedures.
Set the LINE controls to maximum.
Apply a 400 Hz signal at — 19 dB ± 2 dB (69 mV ~
109 mV) to the LINE IN jacks and check for 580 mV.
(Minimum Input Level checks for the LINE inputs).
lights at
full intensity
LINE:
MIC:
DIN
NOTE
To prevent mis-measurcments for the following pro 
cedures. any connection cords other than those for
the respective input check must be removed.
For example: Do not connect the Microphone and
the DIN cords to respective input jacks when check 
ing for the LINE inputs.
IMPORTANT
After this setting is done, do not disturb the Specified
Control Setting of the LINE controls until the re 
maining checks and adjustments are completed.
LINE:
MIC:
t
I
INPUT LEVEL(dB)
J z Z j
Control Setting.
OUTPUT: Specified Setting (See 6-2-2)
Minimum Setting
Minimum Setting
12. Place DOLBY NR IN-OUT-IN/MPX switch to OUT
position, adjust VR108 so that the PEAK level indica 
tor lights as shown in Fig. 6-10, when a 400 Hz signal is
applied at required level to the left channel LINE IN
jack. Keep the right channel LINE IN jack discon 
nected from the AF oscillator.
13. For the right channel, repeat the above procedure
except adjust VR208. Keep the left channel LINE IN
jack disconnected from the AF oscillator.
14. After setting both channels, make sure the indicator
reacts the same as above when required signal is simul 
taneously applied to both channels.
ATTENUATOR
Specified
input level
Specifications:
-19 dB ± 2 dB (69 mV ~ 109 mV)
-67 dB ± 2 dB (274 pV ~ 435 pV)
-35dB± 2 dB (10.9 mV ~ 17.3 mV)
• goes off completely
I
I
I
PEAK LEVEL indicator
Fig. 6-9 Connection