2-19
Note 7:
IIt is advised to use a new cassette tape or an unre-
corded part of a used cassette tape for recording. If a
damaged tape is used for recording, it results not only
in an error of the error rate measurement (measure-
ment result becomes considerably higher than the real
value) but also in loss of the reliability of adjustment.
Note 8:
Switch off the VITERBI function in the playback mode,
because it can be switched off in the playback mode
only. If the VITERBI function is switched off in the play-
back mode, the switched-off status is automatically
cancelled when playback is discontinued. Therefore,
it is required to switch off the VITERBI function in every
playback operation.
2.3.7 Measurement method of P.B. EQ. (error rate)
Neither error rate jig (YTU93083) nor frequency counter is
needed. Error rate is shown on the service support in three
ways of video CH1, CH2 and total. When measuring error
rate by channel, total the video and audio error rates on the
same channel.
If the minimum error rate does not approximate to the stand-
ard value (see Note 7) in spite of repeated adjustments, clean
the head and tape transport system. If cleaning has no ef-
fect on improvement of the error rate, it is thinkable that there
is a failure in the head or the preamp shield, or the P.B. EQ.
(error rate) is incompletely adjusted. In such the case, try to
proceed in P.B. EQ. adjustment with the alignment tape prior
to adjustment of “head REC current”. In other words, if there
is something abnormal in the playback system, the indica-
tion of the error rate is meaningless. Therefore, it is recom-
mended to perform the “P.B. EQ. (error rate) adjustment”
roughly with the alignment tape after completion of the “lin-
earity adjustment” (to adjust error rate to be almost approxi-
mate to the standard value), because it facilitates the adjust-
ment of the “head REC current”.
Note 5:
IThe value of the “head REC current” specified on the
software is not always optimum.
Note 6:
In the strict sense of the word, “approximation to the
standard value” means a value that is slightly lower than
the specified value. Specified values are as follows.
CH1 or CH2: Less than 1,500 (less than 3,000 in total
of CH1 and CH2) with the VITERBI function off.
Difference between channels: Less than 10 times be-
tween CH1 and CH2.
2.3.6 P.B. EQ. (error rate) adjustment (for SP and LP)
Procedure of P.B. EQ. (error rate) adjustment is shown by
the following flowchart.
Yes
No
Record the built-in color bar signal (or EE picture) for
about 5 minutes.
While playing back the recorded signal, adjust the
P.B. EQ. of the “VTR deck” of the “Remote control
utility” in the SP and LP modes respectively.
SP mode: VITERBI off, LP mode:VITERBI on.
When the minimum error rate that is lower than the
standard value is observed as a result of the adjustment,
it is considered that the error rate adjustment is complete.
Note 8
Note 6
Note 6
Check to see if the
measured error rate is minimum
(approximation to the standard value)
or not.