Printronix P4280, Maintenance Manual

Page: 52 / 298

3–26 Troubleshooting
e. If the failure persists, replace the common controller board
(CCB).
7. The 68010 LED lights, but never turns off. Look at the control panel
display:
a. If the top line of the display is blank, the control panel is
probably unplugged or defective. Do the corrective actions listed
in step 5.a.
b. If the display has a single line of black squares on the top
line, the 64180 has failed. Turn off the printer, remove the CCB,
and check the 64180 RTPU PROM at location H8 for bent pins,
pins not inserted, or backwards insertion. Discard any PROMs
that were inserted backwards. Their transistors were reverse
biased, and even if they work their service life has been
shortened by thermal damage. Replace the 64180 RTPU PROM.
Check that the 64180 is correctly inserted and completely seated
in its socket.
c. If the display reads “Diagnostic Test in Progress” and 68010
LED has been on for 20 seconds or more but is not blinking,
it means the 64180 cannot communicate with the 8032 on the
Mech Driver board. Turn off the printer, reseat the cable in J2 of
the CCB and on the Mech Driver board. Check the 8032 on the
Mech Driver, its PROM, and its clock jumper (E1–E2) for
correct insertion, bent pins, etc. (See page 5–60.) Reseat the
jumper and socketed parts. If the problem persists, replace the
Mech Driver’s PROM and the CCB/Mech. Driver cable
assembly W1.