Specifications

4–21Troubleshooting
CCB Diagnostic Checks
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. Turn the printer off.
2. Open the card cage and reseat the CCB and Mech Driver boards.
3. Turn the printer on. Wait at least 15 seconds; while you are waiting
watch the DPU LED at location A2 on the CCB and watch the display on
the control panel. (NOTE: IC locations are shown in Appendix C. The
DPU LED is also identified as “68010,” though some boards may be
silk–screened as “68000.”)
a. When the CCB is operating correctly, the control panel displays
“Diagnostic Tests in Progress,” and the DPU LED turns on for 1 to15
seconds, then turns off. The DPU 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. Turn power off and return the printer to
normal operation.
If the DPU LED turns on and off as described above, but the printer
does work properly, or fails later, go to step 4.
(“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 DPU LED to fault isolate this
message.)
b. If the DPU LED never turns on, it means the 68010 did not
execute the first software instruction in its ROM. Go to step 5.
c. If the DPU 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 6.