HP LaserJet 4300 - damaged fusers


T

tcampbell_nc

I have a LJ 4300tn at a customer site that continues to have problems
with the fuser. I have replaced the fuser 4 times over the last
year.... each time due to output defects. I am replacing the fuser
with HP fusers (not remanufactured but new), and the customer iw
running paper that meets specifications. The current fuser is
developing a defect about 2 inches from the left edge, on the roller.
Presently it appears to be a "discoloration" that is placing a faint,
but noticable, line down the length of the page.

Our last repair to the printer was to replace the High Voltage
Transformer (50.3 Fuser error).

I have called HP, and, of course, the printer is no longer covered by a
warranty. I thought that I would ask here to see if anyone knows of an
issue with the 4300 that would cause repetative damage to new fusers.

Thanks
 
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A

ato_zee

I have a LJ 4300tn at a customer site that continues to have problems
with the fuser. I have replaced the fuser 4 times over the last
year.... each time due to output defects. I am replacing the fuser
with HP fusers (not remanufactured but new), and the customer iw
running paper that meets specifications. The current fuser is
developing a defect about 2 inches from the left edge, on the roller.
Presently it appears to be a "discoloration" that is placing a faint,
but noticable, line down the length of the page.

Our last repair to the printer was to replace the High Voltage
Transformer (50.3 Fuser error).

I have called HP, and, of course, the printer is no longer covered by a
warranty. I thought that I would ask here to see if anyone knows of an
issue with the 4300 that would cause repetative damage to new fusers.
A line or a smudge, suggests that it may be there
before the paper enters the fuser, possibly a toner cartridge/drum fault.
Things are usually diagnosed by switching off the printer mid-print
so you can stop the paper and examine it going into and leaving the
fuser.
http://www.eserviceinfo.com/
Appears to have a free download of the service manual.

Maybe the fuser temp. is out of limits, it's not unknown for triacs and
opto-couplers to fail. So is the fuser bulb cycling on/off, or is it on
more than it should be? There is usually a bi-metal over temp cutout
maybe it is temperature controlling on that.
 
M

Mr Manuals

A line or a smudge, suggests that it may be there
before the paper enters the fuser, possibly a toner cartridge/drum fault.
Things are usually diagnosed by switching off the printer mid-print
so you can stop the paper and examine it going into and leaving the
fuser.
http://www.eserviceinfo.com/
Appears to have a free download of the service manual.

Maybe the fuser temp. is out of limits, it's not unknown for triacs and
opto-couplers to fail. So is the fuser bulb cycling on/off, or is it on
more than it should be? There is usually a bi-metal over temp cutout
maybe it is temperature controlling on that.
I have a file up on one of my sites that 'may' be relevant to your
problem. Its for the 4250-4350 series, check it out at :
http://www.manuals4you.com/free.htm

Feel free to buy something while you're there.
Paul

Want to Fix Something?

http://www.manuals4you.com

http://www.justmanuals.com
Instant download after purchase
 
I

Irv

try printerrepair in yahoo groups.
some good guys participate there

good luck.
 
T

tcampbell_nc

A line or a smudge, suggests that it may be there
before the paper enters the fuser, possibly a toner cartridge/drum fault.
Things are usually diagnosed by switching off the printer mid-print
so you can stop the paper and examine it going into and leaving the
fuser.
http://www.eserviceinfo.com/
Appears to have a free download of the service manual.

Maybe the fuser temp. is out of limits, it's not unknown for triacs and
opto-couplers to fail. So is the fuser bulb cycling on/off, or is it on
more than it should be? There is usually a bi-metal over temp cutout
maybe it is temperature controlling on that.

I have checked the toner drum and the transfer roller... both are
clean. When I said that I have replaced the fuser, I should have
stated that I replaced a full maintenance kit. I am encouraged by your
comments on the fuser temp. You have, however, exceeded my level of
knowledge. Can you offer more details on your ideas?

How does one determine the cycling of the fuser bulb?

How does one determine the temperature (actual) and the temperature
that should be used?

Thanks

TC
 
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A

ato_zee

Can you offer more details on your ideas?

How does one determine the cycling of the fuser bulb?
Ideally visibly, even if you have to remove casing and cheat interlocks.
I suggested a site with the service manual, as did another reply.
Most fusers when idleing are on (heating) for about 20 sec in 2 mins.
How does one determine the temperature (actual) and the temperature
that should be used?
If you have to measure it, a thermocouple or thermistor based thermometer,
some are long thin (a few mm) tubes with the sensor in the tip.
With a bit on ingenuity you can usually trap the tip in place, under a screw
is common. Don't overtighten and damage the tip.
The manual will give the temperature, and how to set it, there
is usually a variable resistance somewhere on the controller
circuit board. The adjustment is to compensate for production
tolerances.
If (not unknown) the power control triac fails short circuit, there
is generally a bi-metal thermostat, otherwise a full power fuser
in contact with paper is a fire hazard. Particularly if someone
goes home at night with a print queue running, and the
printer is in the stationery storeroom. Hence the backup.

The fuser assy is quite simple, the controller for the fuser quite
complex, and part of one or more controller boards and
interlocks.
 
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