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DN--730R
ADJUSTING AND CHECKING THE
MECHANISM SECTION
1. ReplacincTthe Pinch Roller (36)
Before replacincl" tl_e pinch roller, clean the tape contact surface
o[ the pinch roller and the capstan shaft.
Most causes of poor tape transport can be traced to dirty pinch
roller and capstan shaft.
Remove the clips that press the pinch roller and pull the pinch
roller forward to remove it.
After replacing, run a padless C-90 tape to check for tape curls
at the tape guide section of the head.
2. Checking the Pressure Force of the Pinch
Roller (36).
In the playback mo_d.e_hpok a. spring weight opto the bracket at
the center o; the pinch roller. After separating the pinch roller
from the capsta'q s_'aft, allow fl_e pinch roller to contact the caps-
t_n shaft again. Check to make sure the spring weight reads be-
twveen 250-- 350 g when the pinch roller starts to rotate
Replace the pinch roller (36) when it does not conform to the
slandard specification values.
Capstan shaft
li
Pinch roller
: i
_._ 250 -- 350 g
,
(1)
Replacing the Record/Playback Head (14)
How to remove _e RiP HEAD.
1) Remove securing screw (1) and azimuth adjusting
screw (1) from the record/playback head
2) Remove the soldered head wire and disassemble the
mech_,nical unit to remove the record:playback head.
(2) How to assemble the R,,P HEAD.
Reverse the above 1 procedures for removrng the R,"P
HEAD
" Solder the HEAD WIRE according to the diagram
mechanism (re('ordingiplayback head)
4. Replacing the ERASE HI'AD (15)
(1) Unscrew the erase head holding screws (53).
(2) By unsoldering the HEAD W RES can be taken off the
mechanism unit.
(3) When the replacement is completed, secure the screws
with the screw lock
____F--ZZ_-:±-J
5. Checking the Take-up Torque
Load the cassette type torque meter ',SONY TW21:11 ).
Check to make sure that the aver3ge torque meter reading is
within 30-70 g-cm during playback. If it is not within thi,_; range.
check the voltage (approx. 4V) of th_ reel motor. If the voltage is
low, the torque will be weak: if it is high, the torque will be strong
6. Checking the FFand RE\_/ Torques
Load the cassette type torque meier (SONY TW2231). Check to
make sure the torque meter indicates within 90--180 g-cm at
the end of FF and REW.
7. Checking the Back Tension Torque During
Record/Playback
Load the cassette type torque meter (SONY TW2i11): check
to make sure the torque meter read_ between 2 --6 g-cm during
playback and that there is no unevenness
If it is not within this range, replace the reel ass'y (5) or Washer.
8. Checking the FF and REW Times
Load a C-60 cassette tape (DENOI'4 GR-2/60); check to make
sure the tape is fast forwarded o: rewound within 110 sec-
onds. if it is not within this range, rheck sections 5 and 6.
9. Checking the Existence of a Cassette
Housing and the Operation of the Erase
Prevention, Metal and Chrome Switch
Confirm that the sensor arm properl !, detecting the tape type de-
tection holes on the cassette housin(.;
BROWN
BLUE