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3.
If
ramp times vary significantly from specifica-
tions, the ramps should be adjusted by changing
the value of R63. A higher value of R63 results
in a faster ramp time.
4.7.4 READ DATA LEVEL ADJUSTMENT
1.
Connect oscilloscope probe to test point B on the
Transport
Elect~onics
board.
2.
Write short 0-1 binary pattern data blocks- on
track 1.
3.
While reading track 1, adjust potentiometerR25
. on the Transport Electronics board for 15 volts
p-p output as measured at test point B of the Read
Amplifier board.
4.7.5 INTERLOCK SWITCH CHECK AND
ADJUSTMENT
If
READY signal does not go true when the cartridge
is inserted:
1.
Remove Transport Electronics board (four nuts).
2.
Insert tape cartridge until it begins to engage
with the latching mechanism. Contacts on both
interlock switches should begin to open.
3.
Press cartridge inward until it locks in place.
Switch ,contacts should close completely. (This
can be checked by gently pressing the switch
contact toward the switch body. Aily movement
indicates contact is not completely closed.)
Adjustment
If contact will not close completely, loosen switch
mounting screw and readjust switch position for com-
plete contact closure.
4.8
TROUBLESHOOTING
Troubles that can arise in the Model 331 can usually
be classified as either mechanical or electrical. How-'
ever, the classification may often become confusing
because a basically mechanical problem can cause
what appears to be an electronic malfunction and vice
versa. In any case the problem should be thoroughly
analyzed before adjustments are changed.
Electronic troubleshooting is greatly facilitated by
the modular construction - a new card may be sub-
stituted and the effect observed.
~4
406-0331-400
4.8.1· COMPATIBILITY
Model 331 accepts and produces tapes conforming to
the ANSI standards. OccaSionally compatibility prob-
lems can arise. For example:
a.
Cartridges written by and acceptable to the
331 are not acceptable to another transport.
b.
Foreign cartridges cannot be read by the 331
but its own tapes can.
Tape speed and ramp times are important factors in
tape compatibility. These should be checked as de-
scribed under paragraph 4. 7, Checks and Adjust-
ments.
4.8.2 OTHER MALFUNCTIONS
Normal troubleshooting procedures should be used
to locate and isolate electronic malfunctions. The
first items to check are the power supply voltages
on the Transport Electronics board.
IMPORTANT
Power should be off before remov-
ing or inserting circuit boards.
Assuming the power supply voltages are correct,
Table 4-3 or 4-4 should help to isolate the malfunction.
4.9
PARTS REPLACEMENT
Removal and replacement of most items in the Model
331 are obvious. Certain items, such as the photo-
sensor assembly, require adjustment after installa-
tion. Adjustments and any precautions which should
be exercised are described in the following removal
and installation procedures.
4.9.1 PHOTOSENSOR ASSEMBLY REPLACEMENT
Removal
1.
Remove sensor cover (two screws).
2.
Detach sensor's molex connector.
(Carefully
pry it from its rec'eptacle with a small screw-
driver. Rocking connector back and forth can
ruin the contacts.)
3.
Remove two 3/32 inch Allen screws and detach
photosensor assembly from chassis.
Installation
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