The HPLJ4 should display a constant green Ready light and a constant red On Line light to indicate that it is ready to accept print jobs. Additionally, it should display the word "READY" on its LED display. During printing or PostScript translation, the green Ready light will blink on and off. With large or complicated files, this light may blink for several minutes. One should let the job complete if this is happening.
If a job has been sent to the printer but did not print, first make sure that the file sent was a PostScript file. No other file format will make it out of the printer. A common mistake is to send and ASCII file to the printer. The file will result in an error, and nothing will be output. To get around this problem, one should translate the file with the a2ps command, and send this output to the printer (see the online manual page for a2ps for instructions on how this is done). Other files that behave in this manner are those that are not pure Adobe PostScript. Often these come from MacIntosh applications and reference macro files that do not exist. In any case, have a small trusted PostScript file handy to send to the printer in order to determine if the printer is really stuck.
If at this point you feel that the printer is really stuck, you should type the lpq command at the UNIX prompt. A good indication that it is indeed stuck is that there are jobs waiting in the queue, but nothing is happening at the printer. It is sometimes the case that only one machine cannot access the printer, but most other times several or all machines cannot access the queue. For this reason, all of the machines should be looked at with the lpq command.
Resetting or turning the printer off and then back on will sometimes restart printing which will resume processing of the printer queues. First try resetting by holding down the shift button, and then pressing the reset button. If this does not resume printing, then cycle power on the printer. Allow a couple seconds after turning the printer off before turning it back on again. If printing still does not resume, try unplugging the 12V power to the Lantronix EPS1 device. This will always cause a test sheet to be printed, so do not be fooled into believing that you have fixed the printer. Wait until the test sheet prints to see if jobs in the queue(s) start printing.
If at this point the printer is still stuck, more drastic measures are required. Note: I have never had to reboot a UNIX machine to solve a printing problem, so stick with the prescribed method below. VMS machines sometimes require rebooting.
START:
Foreach of (muon tau charm truth up beauty) do
1. Become the root user by typing the "su" command, and
supply the root password. Alternatively, the system
manager can set up the "sudo" command to allow you to
run specified commands as root. Once this is set up, type
"sudo 'command'" to run the specified 'command'. The command
must contain necessary arguments. Example: If the "kill"
command has been set up for you to use with sudo, type
"kill PID" to kill the process id number PID. sudo prompts
you for your password to make sure that it recognizes you.
2. Find the lpd process(es) that are running by typing
"ps ax | grep lpd". This will return the PID number in the
first field. Often there are two lpd processes running.
Foreach (PID number found in step 2 above) do
1. Type "kill -9 PID" (or "sudo kill -9 PID" if you only have sudo privs).
repeat
3. Restart only one lpd process by typing either:
"/usr/lib/lpd" (for DECstations -- charm, truth, up, beauty) or
"/usr/lbin/lpd" (for Alphas -- muon, tau).
4. Check to see if printing has restarted:
a) look at the printer ready light. If it is blinking, then the
printer has been successfully restarted.
b) If the queue you are testing is empty, send a test PostScript
file to the printer to see if it prints.
if (the printer has not restarted) then
a) type:
"lprm -; lpc restart all"
# this step removes all entries from the
# queue. Often it is necessary to type
# "control-c" after each of these commands
# to regain the command prompt.
b) repeat step 4. above
c) if (the printer has not restarted) then goto START
else continue
endif
endif
repeat
The above algorithm should restore printing on all machines. If for some reason you find yourself going through the START label more than twice, it might be helpful to first clear all of the queues on every machine ("lprm -; lpc restart all"), and then proceed trough the algorithm one more time.