JVC HX-Z1, Service Manual

Page: 30 / 54

HX-Z1
30
4.6.3 Electrical Performance
4.6.4 Reference Values for Electrical Function Confirmation Items
Items Measurement conditions Measurement method Standard
Values Adjusting
positions
Adjustment of
recording
bias
current
(Reference
Value) • Mode: Forward or reverse
mode
• Recording mode
• Test tape
: AC-514 to TYPE 2
and AC-225 to
TYPE1
Measurement output
terminal
: Both recording and head-
phone terminals
(1) With the recording and playback mechanism,
load the test tapes (AC-514 to TYPE 2 and AC-
225 to TYPE 1), and set the mechanism to the
recording and pausing condition in advance.
(2) After connecting 100OHM in series to the re-
corder head, measure the bias current with a
valve voltmeter at both of the terminals.
(3) After resetting the [PAUSE] mode, start record-
ing. At this time, adjust VR31 for Lch and VR32
for Rch so that the recording bias current val-
ues become 4.0µA (TYPE 1) and 4.20µA
(TYPE 2).
AC-225
: 4.20 µA
AC-514
: 4.0 µA VR31
Adjustment of
recording and
playback
frequency
characteris-
tics Reference frequency
: 1kHz and 10kHz
(REF.: -20dB)
Test tape
: AC-514 to TYPE 2
Measurement input terminal
: OSC IN (1) With the recording and playback mechanism,
load the test tapes (AC-514 to TYPE 2), and set
the mechanism to the recording and pausing
condition in advance.
(2) While repetitively inputting the reference fre-
quency signal of 1kHz and 10kHz from OSC IN,
record and playback the rape.
(3) While recording and playback the test tape in
TYPE 2, adjust VR31 for Lch and VR32 for Rch
so that the output deviation between 1kHz and
10kHz becomes
-1dB 2dB.
Output
deviation
between
1kHz and
10kHz
: -1dB 2dB VR31
Items Measurement conditions Measurement method Standard
Values Adjusting
positions
Recording
bias
frequency Forward or reverse
• Recording mode
: TYPE 2(AC-514)
• Measurement
terminal : BIAS TP on
P.C. board (1) While changing over to and from BIAS 1 and 2,
confirm that the frequency is changed.
(2) With the recording and playback mechanism,
load the test tape.
(AC-514 to TYPE 2), and set the mechanism to
the recording and pausing condition in ad-
vance.
(3) Confirm that the BIAS TP frequency on the
P.C. board is 100kHz 6kHz.
100 kHz
6 kHz
Eraser
current
(Reference
value) Forward or reverse
• Recording mode
• Test tape
: AC-514 to TYPE 2
and AC-225 to
TYPE 1
terminal : Both of the
eraser head terminals (1) While recording and playback mechanism,
load the test tapes (AC-514 to TYPE 2 and AC-
225 to TYPE 1), and set the mechanism to the
recording and pausing conditions in advance.
(2) After setting to the recording conditions, con-
nect 1W in series to the eraser head on the re-
cording and playback mechanism side, and
measure the eraser current from both of the
eraser terminals.
TYPE 2
: 120 mA
TYPE 1
: 75 mA