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2) Load the deck with a blank test tape YTT-8013.
3) Adjust the signal generator to provide 400 Hz,
-10 dBV {0.3 V) reference ¡nput.
4) Record reference ¡nput signal of 400 Hz,
-10 dBV (0.3V) and then playback the tape
just recorded; the playback output level at the
TAPE OUT jack should be -10 dBV (0.3 V).
If not, adjust the trim pot on the REC PLAY
PCB for the channel to be adjusted.
Trim pots to be adjusted:
R143: Channel 1, 2, 5, 6
R243: Channel 3, 4, 7, 8
1-5-6. Overall Frequency Response
1) Adjust the test set-up as mentioned under
"1-5-5 Recording Level" (Items 1 through 5).
2) Decrease the i nput signal level by 10 dB from
the reference level or set it to -20 dB (0.1 V).
3) Vary the input signal frequency over a range
óf 30 Hz to 16 kHz and record the fre-
quencies, and then reproduce the signáis
just recorded. Measure the reproduced output
leveis at the proper test frequencies, and
make sure that the frequency response is
within the specified limit shown.
4) If the specified frequency response cannot be
obtained by adjusting the REC EQ coil L103
and/or L203, readjust the Bias Level Setting
vvithin its specified range by refering to
"1-5-4. Recording Bias Adjustment". If the
bias leve! is readjusted, the recording level
adjustment will be upset, so repeat the
recording level adjustment again as described
in "1-5-5. Recording Level Adjustment".
(<101
+ 6 -]
+ 4
+ 2
O
-2 -
-4 -
)(
1-6-7. Overall S/N Ratio
1) Set and adjust the test set-up as mentioned
under "1-5-6. Overall Frequency Response".
2) Record the reference input signal, and then
remove the ¡nput plug and continué the re
cording with no signal applied.
3) Reproduce both the reference signal and no
signal just recorded and read the level dif-
ference between the outputs.
4) The dirrerence (S/N) should be higher than
50 dB for each channel, when measured
through a 20 Hz to 20 kHz filter.
5) If the S/N is out of the limit;
* Erase, record/reproduce head and tape path
with a tape eraser.
*Check for normal erasing ratio.
* Readjust the bais traps.
*Recheck the S/N by using another test tape.
1-5-8. Overall Distortion
1) Set and adjust the test setup as mentioned
under "1-5-6. Overall Frequency Response".
2) Vary the signal frequency of the reference in
put signal to 1 kHz, and record and reproduce
the frequency.
3) Measure the distortion; it should be less than
1 %.
4) If not:
* Readjust the bias voitage.
*Try to erase the erase head and record/re
produce head or replace the head(s).
OSCILLOSCOPE
OSCILLATOR
DISTORTION
ANALYZER
SPKR
AMP
AC VOLTMETER
ATTENUATOR
O
o
• • •
UNIT
under TEST
FIg. 1-5-3. Distortion Measurement Set-Up
1-5-9. Erasing Ratio
1) Connect test equipment as shown in Fig. 1-5-1.
and adjust the controls and switches as men
tioned
under "1-5-6. Overall
Frequency
Response".
2) Adjust the signal generator to provide 1 kHz,
O dB (1 V) and record it. Playback the signal
just recorded and read and note the output
level.
3) Rewind the tape up to the beginning of the
tape just recorded. Remove the plug from the
P(3M BUSS IN jack and then record no signal
on the tape just recorded with 1 kHz signal.
4) Rewind the tape just recorded with no
signal and reproduce it. Read the output level
with the level meter sensitivity increased.
1 - 24
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