JVC DD-9 A - Adjustment by Computer Checker; Adjustment Conditions

DD-9A/B/C/E/J/U |
Item
7
Checking 4:
record/play-
back signal
distortion 2.
FL indicator becomes 0.
Checking 1.
signal to
noise ratio
inrecord/ }2.
ing/playback
Record a 1 kHz, 0 VU signal.
Play back the recorded part.
Measure the 0 VU recording output and
the non-signal recording output for com-
Parison using an electronic voltmeter.
Check to see if the value conforms to the
standard value.
Adjustment Adjusting re Remarks
point value
Record a1kHz, —4dBs signal to LINE IN SF/NORM tape; | Be sure to perform this ad-
terminals and perform recording with the Less than 2.5% | justment following — bias
SA/CrO2 tape; | current and recording level
Play back the recorded part. Check the Less than 3% adjustments.
output with a distortion meter to see if Metal tape;
the value conforms to the standard value. Less than 2%
sj
S/F NORM, Apply an output (—72 dBs)
Stop the input by disconnecting from the SA/CrO2 and to the MIC terminals with
terminal to perform non-signal recording. Metal tapes; the recording level
More than trols set to maximum so
42 dB that the FL indicator be-
con-
comes 0.
11. | Checking 1
erasing
coefficient
2
3
4
|
. Perform
. Apply a 1kHz signal to the LINE IN
terminals. Adjust the recording level con-
trols until the FL indicator becomes 0.
recording with the signal en-
hanced by 20 cB.
. Erase a part of the recording.
. Measure the output difference between
the erased part and non-erased part to
compare with an electronic voltmeter.
65 dB
More than] For the measuring, connect a
band pass filter between the deck
and the electronic voltmeter.
Input
(1kHz OVU
+ 20dB)
Tape deck
(recording,
erasing)
Band pass
filter
am)
Electronic
voltmeter
(1 kHz)
[V] Adjustment by computer checker
Use the checker for DD-9 (specified by JVC).
= Adjustment conditions (connection of checker, its switch positions, etc.)
Alligator clip
connecting
TEST SW
TEST PRO! TEST PRO| The places with-
Checking point
Post pin
point (com- SW 2 SW 1 out (__) are re- (computer board)
puter board) lated to the com-
puter board
1 Computer clock TG03 ey point (ICGO2,
2.4) SOU PURSE Die 54 OFF OFF OFF OFF (Checker)
set check
Computer oscil-
3 | lation adjust- 54 ON ON OFF OFF 55 2, 6
I
ment
ai
4 | A/D adjustment 54 ON ON ON ON A/D test point 2, 6
——_—_—_}_ ———
Sensitivity and |
medium-fre-
5 Seer eaualr 54 ON ON ON ON 111, 211 57,46
Zation level
switching
| operation
Bias adjustment OFF ON OFF ON “Tired nee 2,6
terminal)
—— + ———
Hiab Wrequency Remove bias cut
equalization
54
ON
ON
ON
OFF
(Record
head
hee
level switching terminal)
Operation L 2, 6
Co mputer play- When emitting sound
8 | back gain 53 ON/OFF ON OFF OFF 55 from LINE OUT, re-
adjustment move pin 9.
When adjusting, con-
nect pin 9.
2, 6
No. 4198
4