20 Jul
2006
20 Jul
'06
4:25 p.m.
Tony Duell wrote:
The *consumer* manual's big selling point is the description of
printing errors. E.g. "if the print anomaly occurs every
XXX inches, this is the cause; if YYY inches, that is the cause;
I just put calipers on each of the rollers (including the drum from an
empty toner cartridge) and worked it out
Hi,
I've got a Laserjet III that's intermittently throwing Service 50 errors.
Fusing lamp tests good as per
<http://www.fixyourownprinter.com/reference/guides/fuser/sx>. I assume this
means the AC power module has fried itself.
It might do. It might be a lot of other things too.
I'll give a basic overview of what goes on in the various modules, I can
dig out the schematics (which are not in the HP service manual, this is a
somewhat useless document, therefore!), if you want to go further. etc. It also helps with part numbers for replacements
(which,
I believe, the OP was seeking).
The PrinterWorks web site has exploded diagrams of the mechanical stuff,
with part numbers (you guys have it easy, when I started doing there,
there wasn't a web..)
I think it also lists signals (i.e. supplies) available at each of
the various connectors in the machine. For some reason, these
printers had lots of *cable* problems (I suspect the problems
were in the *connectors* on the cables)
Odd.. I've only had connection problems when I've forgotten to plug stuff
back in....
3) A circuit to cotnrol the cooling fan that you
can ignore for the moment.
I have a note about replacing the "upper fan" in an LJ3 with
this type of problem. So, I expect they are related -- if only
indirectly (perhaps loading down a supply when faulty? I'd have to check if the thermistor is PTC or NTC
to see
how that might confuse the MCU)
I am pretty sure that the thermistor resistance decreases with increasing
temperature. But the thermistor circuit runs off the 5V line anyway (see
the value of having full schematics to all the boards....)
-tony