JVC PC-X250 Service Manual page 9

Electrical Performance
Measurement
ITEMS
conditions
Adjustment of Mode:Forward or
recording bias reverse mode
current Recording mode
(Reference Test tape
Value) TDK-60
Measurement output
termial
:Both recording and
headphone terminals
Adjustment of Reference frequency
recording and :1KHz and 8KHz
playback (REF.:-20dB)
frequency Test tape
characteristics TDK-60
Measurement input
terminal
:OSC IN
Reference Values for Electrical Function Confirmation Items
Measurement
Items
conditions
Recording Forward or reverse
bias Test tape
frequency TDK-60
Measurement
terminal : BIAS TP on
P.C. board
Measrrnment methed
1 With the recording and playback
mechanism, load thd test tapes
TDK-60 , and set the mechanism to the recording
and pausing condition in advance .
2 After connecting 100 in series to the
recorder head, measure the bias current
with a valve voltmeter at both of the
terminals
1 with the recording and playback
mechanism, load the test tapes (TDK-60)
and set the mechanism to the
recording and pausing condition in
advance
2 While repetitively inputting the reference
frequency signal of 1KHz and 10KHz from
OSC IN, record and playback the tape.
Measrrnment methed
1 While changing over to and form BIAS 1
and 2, confirm that the frequency is
changed
2 With the recording and playback
mechanism, load the test tape.
(TDK-60 ) , and set the
mechanism to the recording and pausing
condition in advance.
3 Confirm that the BIAS TP frequency on the
P.C. board is 61KHz +/-1KHz
PC-X250
Standard Adjusting
Values positions
4.5 A
+/-0.5 A
Output
deviation
between
1KHz and
8KHz
:-1dB +/-2dB
Standard Adjusting
Values positions
61KHz
+/-1KHz
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