Atari XMM801, Field Service Manual, Page: 26 / 49

CONDITION 1 : While Printer is stopped after power on and home
positioning of Head and sound of Buzzer.
Without the Host and paper.
Al Dip Switches on Centronics Parallel Interface
Board are on.
REF.7-7 Check signals to the Carriage Motor.
-At power-on Time if Head is located at home position,
Pin 3,6,11,14 of IC6 should show just few pulses,
refer to FIG.h just few pulses then stop.
While the head is moving, this pulse remains.
REF.7-8 Check signals for the head which is at Home Position.
-Level on Pin 21 of CPU (7811) should be:
When Head is on home position -------- level low.
When Head is not on home position ---- level high.
REF.7-9 Check if the contents of ROM (27128) are correct.
-Replace the ROM and see the trouble has been solved.
-If no ROM for replacement, follow the next steps of
Flow Chart.
REF.7-10 Check on Carriage Driver Circuits.
Pin 2,7,10,15 of IC6 show the step motor drive pulses
refer to FIG.i.
REF.7-11 Check for Dot Strobe.
-While the head is moving by hand or by power, Pin 20
of CPU (7811) should show the pulse, refer to FIG.k.
-While the head is moving by hand or by power, leg of
R37 should show the pulse, refer to FIG.j.
CAUTION: Moving the head by hand should not be done
for long time, just few seconds only.
REF.7-12 Check for Printer Mechanism.
-If trouble is on head, replace it and test.
-If trouble is not on head, try to replace whole
printer mechanism, then check. Before replacing it,
see thoroughly the mechanism to see for any mechanical
damage.
NOTE: Repair of printer mechanism is not
recommendable.
Special service manual for mechanism repair
will be provided.
REF.7-13 The head should return to home position at power on
time, even so the head is originally located at home
position it should be moved to right and returned to
home position automatically at Power On.
REF.7-14 Test print should be done when the main power switch
Is turned on, while the LF switch is also pressed
down.
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