JVC MX-DVB10, Service Manual

Page: 29 / 131

MX-DVB10
1-29
Items Measurement
conditions
Measurement method
Standard
values
Adjusting
positions
1. With the recording and playback mechanism,
load the test tapes (AC-225 to TYP ), and set the
mechanism to the recording and
pausing conditions 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.
3. After resetting the [PAUSE] mode, start recording.
At this time, adjust VR101 for LcH and VR201 for
RcH so that the recording bias current values
become 4.0 A (TYP ).
1. With the recording and playback mechanism, load
the test tape (AC-225 to TYP ), 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 test tape.
3. While recording and playing back the test tape in
TYP , adjust VR101 for LcH and VR201 for RcH
so that the output deviation between 1kHz and
10kHz becomes -1dB 2dB.
Adjustment of
recording bias
current
(Reference
value)
Adjustment of
recording and
playback
frequency
characteristics
*Mode : Forward or
reverse mode
*Recording mode
*Test tape
: AC-225
Measurement output
terminal
:Both recording and
headphone terminals
Reference frequency
:1kHz and 10kHz
(REF:-20dB)
Test tape
:TYP AC-225
Measurement input
terminal
:OSC IN
AC-225
:4.20 A
Output
deviation
between
1kHz and
10kH
:-1dB 2dB
LcH
:VR101
RcH
:VR201
LcH
:VR101
RcH
:VR201
Electrical performance
Items Measurement
conditions
Measurement method
Standard
values
Adjusting
positions
1. With the recording and playback mechanism.
load the test tape (AC-225 to TYP ), and set the
mechanism to the recording and pausing
conditions in advance.
2. Confirm that the BIAS TP frequency on the
P.C. board is 100kHz 6kHz.
1. With the recording and playback mechanism,
load the test tapes (AC-225 to TYP ), and set the
mechanism to the recording and pausing condition
in advance.
2. After setting to the recording conditions, connect
1M in series to the eraser head on the recording
and playback mechanism side, and measure the
eraser current from both of the eraser terminal.
Recording
bias frequency
Eraser current
(Reference
value)
*Recording and
playback side forward
or reverse
*Test tape
:TYP AC-225
*Measurement
terminal BIAS TP on
P.C. board
*Recording and
playback side forward
or reverse
*Recording mode
*Test tape
:AC-225
Measurement terminal
Both of the eraser
head
100kHz
+9kHz
-7kHz
TYP
:75mA
Reference values for electrical function confirmation items