Printronix

P9212 Maintenance Manual page 105

d. If the 68010 LED blinks steadily at 1 blink per second, it means
e. If the 68010 LED blinks steadily 5 times per second, it means
4. The 68010 LED turns on, then off, but the printer doesn't work. Look at
the control panel display:
Troubleshooting
that the 68010 ROMs are bad. Turn off the printer, remove the CCB,
and check that all ROM chips are inserted in the correct position and
with all pins inserted correctly.
This check will catch out–of–order ROMs and all single and multiple
bit failures of floating–gate EPROMs (the type with the window, that
erase with ultraviolet light).
If a ROM chip was inserted backwards, discard it. Even if it operates
properly, a high current flowed through the backwards–biased
transistors, and its service life is probably shortened due to thermal
damage.
If ROMs appear correctly inserted, they may still be defective.
Sometimes bits "fade" to one when internal floating gates discharge.
This can occur from over–voltage programming, radiation damage,
too many EPROM erasures, etc. Install new program PROMs.
CCB RAM has failed. The most common cause of this failure during
maintenance is turning off the printer too briefly for the 64180 to
reset. The 64180 shares memory with the 68010, and writes to RAM
if it is not completely reset. Turn the printer off, wait at least 15
seconds, then recycle power before accepting this indication of CCB
RAM failure.
The RAM chips are at board coordinates N9 and P9. The sockets at
N8 and P8 are normally empty; this will not cause a RAM failure.
Inspect the RAM chips, sockets and traces for shorts or missing
chips. Damaged traces or sockets call for replacement of the CCB.
A remote possibility is failure of the 64180 in the start–up handshake
or in the code that programs the memory controller. Try changing the
64180 RTPU PROM.
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