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Section VI
6-58.
TROUBLESHOOTING TABLE
6-59.
Table 6-3 lists trouble symptoms with possible
causes and procedures.
6-60.
TEST A
6-61.
This test exercises:
Both motor drive circuits
Both motors and encoders
The servo chips
Error light circuit
Gate arrays
Microprocessor
ROM
a.
Load a sheet of paper.
b.
Manually move the pen carriage near the center
of its travel.
c.
Hold the ENTER pushbutton down while setting
the LINE swit.ch to ON. The ERROR light should
remain ON.
d.
Press the - cursor pushbutton.
1.
ERROR light should turn ON and OFF conti-
nuously (approximately one second for each
state).
2.
Pen carriage should move left and right about
6.4 mm (0.25 in.) continuously.
Model 7475A
3.
Paper should move back and forth about
6.4 mm (0.25 in.) continuously.
6-62.
TESTB
NOTE
Test may be stopped by pressing
ENTER and resumed by press-
ing - . Plotter will not operate in
any other mode until power has
been turned OFF and ON.
6-63.
This test helps to isolate problems to motors/
encoders or logic circuits when a failure is accompanied
by the ERROR light flashing ON/OFF at about one
second per cycle. An oscilloscope is required.
a.
Disconnect the interface cable for this test.
b.
Hold down each of the four cursor directional
pushbuttons, one at a time.
If
a control stops the
ERROR light from flashing (stays either ON or
OFF while the button is held down) the failure is
associated with one of the following general areas.
t -
X saturation line
}
Paper Drive
I -
X error line
- - Y saturation line
} Pen Drive
- - Y error line
Table 6-3. Troubleshooting
SYMPTOMS
POSSIBLE CAUSES/PROCEDURES
Does not respond to any front-
Rear-panel line fuse (see Table 1-3).
panel controls. ERROR light is
Power supplies. Check voltages and
OFF with PAPER lever in
power supply fuses on PCA
LOAD position.
4MHzclock
GateArrayB
Responds to front-panel controls
I/O connector not seated properly (may
but not to external controller.
produce an error indication at controller).
Test I/O circuits by sending:
"SP1;SP2" from controller.
Does not operate properly.
Go to Test B in this section.
ERROR light flashes (PAPER
lever
in
HOLD) about 1 second
per ON/OFF cycle.
Pen up/down does not operate.
Check fuse (A1F2) and pen supply voltage.
Check solenoid continuity.
Paper slips while plotting.
Pinchroller worn. Replace both pinchrollers.
Pinchroller arm spring loose or broken.
Diagonal lines not straight:
Especially near horizontal lines
Defective pen drive motor/encoder assembly
Especially near vertical lines
Defective paper drive motor/encoder
assembly
Deposits on gritwheels, pinchrollers or
slider rod. Clean slider rod and pinch-
rollers with a dry wiper.
6-8
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Table of Contents
Troubleshooting
