Teac A-2300SD - Track-to-Track Cross Talk Rejection; Channel-to-Channel Cross Talk Rejection; Optimum Erasure Measurement; Dolby Encoder Check (Playback)

9-26 TRACK-TO-TRACK CROSS TALK
REJECTION
Following is the measurement procedure at 7-1/2 ips using
the TEAC standard tape, Type YTT-8013:
1. Thread a blank tape or the YTT-8013 tape on the unit.
2. Apply a 125 Hz signal at -8 dB to the right channel
LINE IN jack.
3. Make a 30 second recording of the 125 Hz signal.
4. Interchange the left and right reels and re thread tape
on the unit.
5. Connect a VTVM to the right channel OUTPUT jack.
6. Playback the recorded signal portion of tape and
monitor the level on the VTVM.
7. The reading should be -35 dB or less.
9-27 CHANNEL-TO-CHANNEL CROSS TALK
REJECTION
Following is the measurement procedure at 7-1/2 ips using
the TEAC standard tape, Type YTT-8013;
1. Apply a 1 kHz signal at the operating level of -8 dB,
to the left channel LINE IN jack.
2. Install a short-circuiting plug to the right channel LINE
IN jack.
3. Make a 30 second recording on both channels, then
rewind to beginning of this recording.
4. Connect a VTVM or equivalent, to the right channel
OUTPUT jack through a 1 kHz Narrow Band Pass
Filter.
5. Put unit in PLAY mode and monitor the “no signal”
right channel on the VTVM.
The reading should be -45 dB or less.
9-28 OPTIMUM ERASURE MEASUREMENT
1. Apply a 1 kHz signal at 10 dB above the operating
level of -8 dB, to the left channel LINE IN jack.
2. Make a 30 second recording of the above signal and
rewind to begining of this recording.
3. Disconnect the 1 kHz signal source (A.F oscillator)
from the LINE IN jack.
4. Connect a VTVM or equivalent, to the left channel
OUTPUT jack, through a 1 kHz Narrow Band Pass
Filter
5. Set the unit output switch to “TAPE monitor”.
6. Put unit in the REC mode and “record” (erase) over
this previous recording; then rewind to begining again.
7. Put unit in PLAY mode and monitor the left channel
output on the VTVM.
8. Difference in output level, compared to the above
recording level, should be more than -68 dB.
9. Repeat the same procedure on the right channel.
9-29 DOLBY ENCODER CHECK (PLAYBACK)
1. Place the DOLBY NR SW to IN, FM/COPY SW to IN,
and the MONITOR SW to SOURCE position.
2. Turn the FM/COPY LEVEL L and R (VR-501/504)
on the back panel to maximum.
3. Apply a 100 Hz signal at-38 dB at the LINE IN jacks.
4. Adjust FM/COPY LEVEL L and R for -30 dB at
OUTPUT jacks.
5. Change the Input signal frequency to 5 kHz at-48 dB.
The OUTPUT level should read -50 dB ±1 dB.
6. If readings are not within limits, recheck adjustments of
DOLBY ENCODER PC Board.
9-30 DOLBY DECODER CHECK
6. Place the DOLBY FM/COPY SW to OUT, DOLBY NR
SW to OUT, REC BIAS SW and REC EQ SW to #1
position, tape SPEED SW to 7-1 /2 ips (HIGH) position.
7. Thread a blank TEAC YTT-8013 on the unit.
8. Record approx. 10 seconds each of a 1 kHz signal at
-28 dB and a 10 kHz signal at—48 dB.
9. Rewind the tape, playback the recorded signals but
while watching the VTVM set the DOLBY NR SW to
IN position.
10. Comparing the outputs between DOLBY NR SW-OUT/
IN, check at 1 kHz for a decline of 5 dB; at 10 kHz for
decline of 10 dB.
11. If readings are not within limits, recheck and adjust
DOLBY DECODER PC Board.
9-31 DOLBY NR CHECK
12. Place the DOLBY FM/COPY SW to OUT, DOLBY NR
SW to IN position. REC BIAS SW and REC EQ SW to
#1 position, tape SPEED SW to 7-1/2 ips (HIGH).
13. Apply signals swept from 40 Hz to 22 kHz at -38 dB to
LINE IN jacks and record.
14. Change the tape SPEED SW to the 3-3/4 ips (LOW)
position.
15. Apply signals swept from 40 Hz to 1 6 kHz at—38 dB.
16. Check for best response. No further adjustment is
provided.
19