JVC SR-VS30U Service Manual page 14

4.4 Mechanism adjustment
Before using test tapes, tape transporting past should be demagnetized.
* Adjustments required after head replacement are marked with an asterisk(*).
Item Conditions
* Adjusting Test tape : VT704
Head or VT705 (12.5 kHz)
azimuth
Adjusting 1. Test tape :
tape speed VT712 (3 kHz)
(motor speed) After adjustment
of normal speed,
then adjust high
speed.
2. For high speed
adjustment, set
the deck for play
mode and short
circuit between
B7101 and GND.
Checking Test tape : VT712 (3
wow and kHz)
flutter
Torque gauge :
Checking
play back TW2111 (FWD)
torque TW2121 (REV)
Checking Torque gauge :
back TW2111 (FWD)
tension TW2121 (REV)
Checking Tape : AC-225
FF/REW
time
1-14 (No.MB061)
Adjustment and Confirmation
1. Connect an electronic voltmeter to the LINE
OUT terminals.
2. Play back the VT704 (12.5 kHz) test tape.
3. Adjust the head angle with the screw (FWD
and REV) until the reading of the electronic
voltmeter becomes maximum for both
channels (phase difference must be "0".)
Repeat the adjustment in FWD and REV
4. modes as well as for the decks A and B.
1. Connect a frequency counter to the LINE OUT
terminals.
2. Perform normal speed adjustment first, and
3. then do high speed adjustment.
Play back the VT712 test tape.
Adjust for decks A. :
Adjust VR701 for normal speed at 3000 Hz,
and VR702 for high speed at 6000 Hz.
4. Adjust for decks B. :
Adjust VR703 for normal speed at 3000 Hz,
and VR704 for high speed at 6000 Hz.
Difference in FWD and REV frequencies must
be less than 48 Hz.
1. Connect a wow and flutter meter to the LINE
OUT terminals.
2. Play back the VT712 test tape.
3. Check to see if the reading of the meter is
within 0.17 % (WRMS).
Employ a torque testing cassette tape
(TW2111[FWD] / TW2121[REV]) for the
checking, or remove the cassette cover and use
a torque gauge.
Employ a torque testing cassette tape
(TW2111[FWD] / TW2121[REV]) for the
checking, play the torque gauge and read the
back tension value to confirm that the back
tension is 1 - 5 g cm.
Play back AC-225 tape in FF/REW mode, check
that the FF/REW time during tape running from
begin to end.
Standard value Adjust point
Maximum Screws
(FWD, REV)
Deck B
FWD
Deck A
FWD
Normal speed: Deck A :
Deck A,B ; Normal ; VR701
3000 15 Hz High ; VR702
High speed: Deck B :
Deck A,B ; Normal ; VR703
6000 30 Hz High ; VR704
Less than 0.17 %
(WRMS)
27 - 70 g cm
1 - 5 g cm
Less than 120 sec
REV Adj.
REV Adj.