Teac A-3440 - Optimum Erasure Measurement; Channel Separation; Bias Leakage Check; Distortion Check

11-6 OPTIMUM ERASURE MEASUREMENT
Tape SPEED SELECTOR SW . HIGH (15 ips)
. Thread the YTT-8013 test tape on the deck.
2. Apply a 1 kHz signal at 10 dB above the specified level
of —12 dB (195 mV) to LINE IN jack 1.
3. Make a 30 second recording of the above signal and re-
wind to the beginning of the recording.
4. Disconnect the 1 kHz signal source from the LINE IN
jack.
5. Connect a VTVM to the OUTPUT jack 1 through a 1 kHz
Narrow Band Pass Filter.
6. Set the OUTPUT SELECT SW to PLAY position.
. Put deck in the RECORD mode and “record” (erase)
over this previous recording, then rewind to beginning
again.
8. Put deck in PLAY mode and monitor the Channel 1
output on the VITVM.
9. The difference in output level compared with the above
recording level should be more than 65 dB.
10. Repeat this procedure for the other channels.
—y
~
NOTE: Do not overlook filter loss when making this meas-
urement.
OSCILLATOR
ATTENUATOR
DECK
under TEST
Fig. 8-13 Test Connections for Erase Measurement
11-7 CHANNEL SEPARATION
OUTPUT SELECT SW........... PLAY
TAPE SPEED SELECTOR SW HIGH (15 ips)
FUNCTION SELECT SW......... all ON
NOTE: Be sure that the Line and Level controls are still
at their specified positions.
1. Apply a 1 kHz signal at —8 dB (308 mV) to channels 2,
3 and 4.
2. Place deck in the Record mode.
3. While recording measure the output from channel | with
a VTVM connected through a 1 kHz bandpass filter. The
level should be —48 dB or better. (Spec. 40 dB)
4. Depress the STOP button.
OSCILLOSCOPE
ATTENUATOR
Tape2-1
Fig. 8-14 Test Connections for Channel Separation Check
11-8 BIAS LEAKAGE CHECK
OUTPUT Level Control ..... Maximum
6. Remove the Head Housing. Connect a VIVM to the OUT-
PUT jack.
7. Place the OUTPUT SELECT SW to PLAY position.
. Put the deck in the Record mode.
9. Adjust TRAP L101 for minimum bias leakage reading at
the OUTPUT jack. Reading should be —48 dB or less with
the OUTPUT SELECT SW in any position.
11-9 DISTORTION CHECK
1. Thread the YTT-8013 test tape on the deck.
2. Apply a 1 kHz signal to the LINE IN jack at 0 VU.
3. With the Line and Output Level Controls set to the
specified position, place the deck in the record mode for
approx. 30 seconds.
4. Rewind and play this recorded section of the tape.
. The distortion read on the distortion analyzer should
be 1.0%, or less.
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