If the minimum error rate does not approximate to the stand-Note 7:IIt is advised to use a new cassette tape or an unre-
ard value (see Note 7) in spite of repeated adjustments, cleancorded part of a used cassette tape for recording. If a
the head and tape transport system. If cleaning has no ef-damaged tape is used for recording, it results not only
fect on improvement of the error rate, it is thinkable that therein an error of the error rate measurement (measure-
is a failure in the head or the preamp shield, or the P.B. EQ.ment result becomes considerably higher than the real
(error rate) is incompletely adjusted. In such the case, try tovalue) but also in loss of the reliability of adjustment.
proceed in P.B. EQ. adjustment with the alignment tape priorNote 8:Switch off the VITERBI function in the playback mode,
to adjustment of Ohead REC current�. In other words, if therebecause it can be switched off in the playback mode
is something abnormal in the playback system, the indica-only. If the VITERBI function is switched off in the play-
tion of the error rate is meaningless. Therefore, it is recom-back mode, the switched-off status is automatically
mended to perform the OP.B. EQ. (error rate) adjustment�cancelled when playback is discontinued. Therefore,
roughly with the alignment tape after completion of the Olin-it is required to switch off the VITERBI function in every
earity adjustment� (to adjust error rate to be almost approxi-playback operation.
mate to the standard value), because it facilitates the adjust-
ment of the Ohead REC current�.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 threeNote 5:IThe value of the Ohead REC current� specified on the
ways of video CH1, CH2 and total. When measuring error
software is not always optimum.
rate by channel, total the video and audio error rates on theNote 6:In the strict sense of the word, Oapproximation to the
same channel.
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.
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 OVTR deck� of the ORemote control
utility� in the SP and LP modes respectively.
SP mode: VITERBI off, LP mode:VITERBI on.
Note 8
Check to see if the
measured error rate is minimum
(approximation tthe standard value) o
Noor not.
Note 6
Yes
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 6
2-19 |
ACEC
JVC
