Specifications

3–21Troubleshooting
Diagnostic Check of Microprocessors
This procedure checks the operation of the microprocessors and IC chips on
the Common Controller (CCB) and Mechanism Driver boards. Do the steps
in the order presented.
1. Set the power switch to O (off).
2. Remove the paper guide assembly (page 5–42).
3. Reseat the CCB and Mech Driver boards in the card cage.
4. Set the power switch to 1 (on). Wait at least 15 seconds; while you are
waiting watch the 68010 LED at location A2 on the CCB (some boards
may be silk–screened as “68000”) and watch the display on the control
panel. (NOTE: IC locations are shown on page 5–52.)
a. When the CCB is operating correctly, the control panel displays
“Diagnostic Tests in Progress,” and the 68010 LED turns on for
1 to15 seconds, then turns off. The 68010 LED turns off after the
68010 successfully tests itself, RAM, 68010 ROM, and
communication with the 64180 CPU. The more RAM or ROM
installed in the printer, the longer the LED is on, but it always
turns on then off when the CCB is functioning correctly. If the
printer turns on normally, the CCB is okay. Install the EMI shield
and return the printer to normal operation.
If the 68010 LED turns on and off as described above, but the
printer does work properly, or fails later, go to step 5.
(“Dynamic RAM Fault” on the display can mean the 64180 has
waited 15–20 seconds without getting its handshake from the
68010. The following substeps use the 68010 LED to fault
isolate this message.)
b. If the 68010 LED never turns on, it means the 68010 did not
execute the first software instruction in its ROM. Go to step 6.
c. If the 68010 LED stays on for 30 seconds but never blinks, it
means RAM and ROM for the 68010 are okay, but the 64180 is
not executing instructions. Go to step 7.
d. If the 68010 LED blinks steadily at 1 blink per second, it means
that the 68010 ROMs are bad. Turn off the printer, remove the