Laser fuser thermal switches?

[T i m]

Hi all,

I fault found (what I believe is) an open cct thermal switch in the
fuser of a 'faulty' Samsung CLX 3175 laser printer I was recently
given.

https://dl.dropboxusercontent.com/u/5772409/Thermal%20switch.jpg

One is marked 170/0 100209 and the other is unmarked.

Because it looks like there are two in series, as a test I shorted one
out and the printer fired up and seemed to work ok. ;-)

So, am I right in thinking there are two in series as a failsafe and
they are used as an overtemp and that the actual temperature might be
managed by a thermister and finer / electronic (PWM?) controls?

I believe I could buy a new fuser at a reasonable price and that would
obviously come with a pair of new thermal switches but as the fuser is
otherwise working it would be nice if I could simply replace this
faulty device (and if so from where please)?

Cheers, T i m

 

I think the fuser temperature is pretty much determined by its current draw (resistance) and any control is simply on or off. Looks like those are just to kep it from burning the house down.

Why there are two is a mystery to me. Maybe it consists of two elements in series and if one shorts it would trigger ? Something like that ?

 

T i m <news@spaced.me.uk> wrote:

I fault found (what I believe is) an open cct thermal switch in the
fuser of a 'faulty' Samsung CLX 3175 laser printer I was recently
given. [...]

So, am I right in thinking there are two in series as a failsafe

This is probably true.

> and they are used as an overtemp

Could be an overtemp, could be a normal operating control. Sometimes
there will be an "operating" thermostat at X degrees C in series with
a "limit" thermostat at (say) X+20 degrees C. In this configuration,
sometimes the operating thermostat is designed to turn on and off
indefinitely, but the limit thermostat is more of a thermal fuse - it
opens the circuit once and stays open forever after that.

and that the actual temperature might be managed by a thermister and
finer / electronic (PWM?) controls?

Maybe. It could be that the electronic control has also failed for some
reason, such that the printer appears to work in a short test, but if
you leave it on for a long time or run a long print job, it might
overheat again. If you do replace the switch, it's probably a good idea
to run the first several print jobs while you/someone is nearby, to shut
off the printer in case of excitement.

I believe I could buy a new fuser at a reasonable price and that would
obviously come with a pair of new thermal switches but as the fuser is
otherwise working it would be nice if I could simply replace this
faulty device (and if so from where please)?

That looks like the Korean interpretation of a Klixon 7BT2 thermostat.
They are available in a variety of mounting options and terminal types,
but all with pretty much the same size body.
http://www.sensata.com/klixon/thermostat-precision-7bt2.htm

The White-Rodgers 3L11 series is similar, but the ones I can find
quickly all have a mounting foot, which you may not need in your
application. These are distributed in small quantities by Mouser (US):
http://www.mouser.com/ProductDetail/White-Rodgers/3L11-325/?qs=sGAEpiMZZMusbZ2pNxAMx%2f729FK%252btZH%2fyKEVnol6%252b%2f4%3d
(or search 3L11-325 at mouser.com)

Cantherm R53 series also appears to be similar. These are distributed
in small quantities by Digi-Key (US):
http://www.digikey.com/product-detail/en/CS715025Z/317-1553-ND
The ones Digi-Key sells come with a mounting flange, but it looks like
it would be easy to remove this with pliers.

Hopefully the "170" in the part number on yours means 170 C, but it
would be good to find out for sure.

It looks like your two thermostats have been joined by spot-welding the
terminals; you may have to replace both thermostats and come up with a
way to join the terminals on your own - a really short jumper wire,
perhaps.

In the US, these are all over the place inside home refrigerators,
clothes dryers, etc. An appliance repair shop will probably have some,
but they will probably only know them by the manufacturer part number
and not just the fact that it's for 170 C or whatever.

Standard disclaimers apply: I don't get money or other consideration
from any companies mentioned.

Matt Roberds

 

The main reason I figured the temperature is self regulating is that the fuser is one of those parts that are different on a 120 volt unit or a 240 volt unit. It probably just kicks on with a relay.

I could be wrong, but I doubt they could get precise enough temperature control out of one of those little bimetal jobs to assure consistent print quality.

Of ocurs eI could be wrong, but there is still usually a different part for 24 volt operation, whereas most modern power supplies switch automatically.. Some don't even need to switch, they just have good enough regulation to run fine anywhere from 50 - 250 VAC.

 

[T i m]

On Mon, 13 Jan 2014 12:06:21 -0800 (PST), jurb6006@gmail.com wrote:

>I think the fuser temperature is pretty much determined by its current draw (resistance) and any control is simply on or off.

Ok.

> Looks like those are just to kep it from burning the house down.

;-)

>Why there are two is a mystery to me. Maybe it consists of two elements in series and if one shorts it would trigger ? Something like that ?

Don't think so in this case as these thermal switches are connected in
series and with no other connections etc, and I can only see the ends
for one heater / lamp?

https://dl.dropboxusercontent.com/u/5772409/Fuser.jpg

I think the two in series is as you say and a safety thing ... and as
only one is marked they are possibly both the same temperature rating.

I have seen n/c thermal switches and assuming 170 marking is the
temperature in Centigrade, I could potentially get a similar
replacement but they are set in holes and facing the fuser roller so
the dimensions could be reasonably critical.

I guess I could just run the printer, turning it on and off as
required and if it seems reliable / useful, treat it to a new fuser in
any case?

Cheers, T i m

 

[T i m]

On Mon, 13 Jan 2014 20:31:01 +0000 (UTC), mroberds@att.net wrote:

T i m <news@spaced.me.uk> wrote:
I fault found (what I believe is) an open cct thermal switch in the
fuser of a 'faulty' Samsung CLX 3175 laser printer I was recently
given. [...]

So, am I right in thinking there are two in series as a failsafe

This is probably true.

and they are used as an overtemp

Could be an overtemp, could be a normal operating control. Sometimes
there will be an "operating" thermostat at X degrees C in series with
a "limit" thermostat at (say) X+20 degrees C. In this configuration,
sometimes the operating thermostat is designed to turn on and off
indefinitely, but the limit thermostat is more of a thermal fuse - it
opens the circuit once and stays open forever after that.

Ah, that makes sense and was another option I considered (and the code
on the pair could have been a Samsung part number for the two devices
combined as a 'solution' (they are cold welded together with a
bridging plate).

and that the actual temperature might be managed by a thermister and
finer / electronic (PWM?) controls?

Maybe. It could be that the electronic control has also failed for some
reason, such that the printer appears to work in a short test, but if
you leave it on for a long time or run a long print job, it might
overheat again.

The paper certainly comes out pretty warm but then I think this is the
case when they have upped the page rate? The paper isn't curled etc,
if that says anything?

If you do replace the switch, it's probably a good idea
to run the first several print jobs while you/someone is nearby, to shut
off the printer in case of excitement.

Hehe. I have probably put 60 pages though it whilst testing today and
it seems to have survived that ok. However and as I mentioned just,
the paper did feel pretty warm (I can put the IR thermometer on it and
see what sort of temps are going on).

I believe I could buy a new fuser at a reasonable price and that would
obviously come with a pair of new thermal switches but as the fuser is
otherwise working it would be nice if I could simply replace this
faulty device (and if so from where please)?

That looks like the Korean interpretation of a Klixon 7BT2 thermostat.
They are available in a variety of mounting options and terminal types,
but all with pretty much the same size body.
http://www.sensata.com/klixon/thermostat-precision-7bt2.htm

<checks link> Thanks for that, plenty of choice there. I did have a
quick look for a Service Manual as there may well be some calibration
/ temperature measurements in there but as yet, only have the parts
section (with exploded diagrams).

The White-Rodgers 3L11 series is similar, but the ones I can find
quickly all have a mounting foot, which you may not need in your
application. These are distributed in small quantities by Mouser (US):
http://www.mouser.com/ProductDetail/White-Rodgers/3L11-325/?qs=sGAEpiMZZMusbZ2pNxAMx%2f729FK%252btZH%2fyKEVnol6%252b%2f4%3d
(or search 3L11-325 at mouser.com)

Cantherm R53 series also appears to be similar. These are distributed
in small quantities by Digi-Key (US):
http://www.digikey.com/product-detail/en/CS715025Z/317-1553-ND
The ones Digi-Key sells come with a mounting flange, but it looks like
it would be easy to remove this with pliers.

Again, that was something I also considered.

Hopefully the "170" in the part number on yours means 170 C, but it
would be good to find out for sure.

I guess I could test the remaining working one with a DMM, heat gun
and IR thermometer?

It looks like your two thermostats have been joined by spot-welding the
terminals; you may have to replace both thermostats and come up with a
way to join the terminals on your own - a really short jumper wire,
perhaps.

Understood.

In the US, these are all over the place inside home refrigerators,
clothes dryers, etc. An appliance repair shop will probably have some,
but they will probably only know them by the manufacturer part number
and not just the fact that it's for 170 C or whatever.

Also understood. I have changed such (and thermal fuses) on a few
things now.

Standard disclaimers apply: I don't get money or other consideration
from any companies mentioned.

Understood. ;-)

As the fuser comes as an assembly and therefore no sub-part
information is available, I might just run the printer as-is for a
while (switching on and of as required) and if it proves reliable,
then maybe treating it to a new fuser in any case. At least that way I
might be able to see if there are any more useful markings on the new
one and if so, see if they are indeed just in duplicate (switch +
switch) or as you say, something more final, like switch + thermal
fuse (and have the old fuser for other spares). ;-)

Cheers and thanks for all the links etc.

T i m.

 

[Jeff Liebermann]

On Mon, 13 Jan 2014 19:57:41 +0000, T i m <news@spaced.me.uk> wrote:

I fault found (what I believe is) an open cct thermal switch in the
fuser of a 'faulty' Samsung CLX 3175 laser printer I was recently
given.

What is "faulty" about the Samsung CLX 3175 printer?
Are you getting an error message on the front panel?
Is it perhaps a "Deve Home Sensor Error" message?

--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[T i m]

On Mon, 13 Jan 2014 15:15:11 -0800, Jeff Liebermann <jeffl@cruzio.com>
wrote:

On Mon, 13 Jan 2014 19:57:41 +0000, T i m <news@spaced.me.uk> wrote:

I fault found (what I believe is) an open cct thermal switch in the
fuser of a 'faulty' Samsung CLX 3175 laser printer I was recently
given.

What is "faulty" about the Samsung CLX 3175 printer?

Nothing now. ;-)

>Are you getting an error message on the front panel?

I was.

>Is it perhaps a "Deve Home Sensor Error" message?

No, it was something about cycling the power (that made no difference)
but a Goggle search from that suggested a fuser fault (as one of the
main causes).

The fuser was indeed cold and (as it turned out) because of what looks
like a thermal switch (or fuse) that had gone o/c. Shorting said
device with some copper wire removed the error message and allowed the
printer to return to a working condition. ;-)

That said, because I don't know of the type / function of the o/c
device, I now may not have either:

1) The extra safety functionality (thermal fuse)

2) The right running temperature (two different temperature threshold
devices in series and the lower temp unit has failed).

As what is probably and aside I'm also seeing a horizontal band across
the page. It could be off the OPC drum. I'll have to measure the
circumference but it looks about right.

Cheers, T i m

 

[T i m]

On Mon, 13 Jan 2014 15:11:46 -0800 (PST), jurb6006@gmail.com wrote:

>The main reason I figured the temperature is self regulating is that the fuser is one of those parts that are different on a 120 volt unit or a 240 volt unit.

Understood.

> It probably just kicks on with a relay.

I think I read somewhere that someone had changed a thyristor (triac?)
on the SMPS but it could be used in the same on/off way of course.

This is the PSU:

https://dl.dropboxusercontent.com/u/5772409/Samsung%20PSU.jpg

The input (240V in this case (UK)) is in the bottom left and the
output to the fuser on the bottom right.

I could be wrong, but I doubt they could get precise enough temperature control out of one of those little bimetal jobs to assure consistent print quality.

That was what I was thinking and why I wondered if the thermistor
(that also sits over the fuser roller and beside the thermal switches
/ fuse) may control it more finely. Mind you, even the temperature
range you might see with something with the hysteresis of a bi-metal
switch may not be sufficient to affect the ability to fuse toner (I
don't know if that is the case etc).

Of ocurs eI could be wrong, but there is still usually a different part for 24 volt operation,

There is indeed (assuming you meant 240V there). I have seen them both
in the parts list and the voltage would (of course) affect both the
rating of the heater / lamp and the thermal switch (working voltages,
although they would probably be 240 in either case).


> whereas most modern power supplies switch automatically. Some don't even need to switch, they just have good enough regulation to run fine anywhere from 50 - 250 VAC.

Clever aren't they. ;-)

Cheers, T i m

 

[Jeff Liebermann]

On Mon, 13 Jan 2014 23:27:47 +0000, T i m <news@spaced.me.uk> wrote:

No, it was something about cycling the power (that made no difference)
but a Goggle search from that suggested a fuser fault (as one of the
main causes).

Duz this sound familiar?
<http://www.fixyourownprinter.com/forums/printer/72871>
See 2nd to last comment near bottom of page. That's my favorite fix
of mechanical thermostats.

The fuser was indeed cold and (as it turned out) because of what looks
like a thermal switch (or fuse) that had gone o/c. Shorting said
device with some copper wire removed the error message and allowed the
printer to return to a working condition. ;-)

Finding the exact replacement has been a bit of a challenge. This is
the best I can do for now:
<http://www.alibaba.com/product-gs/982359539/PT056_Replacement_for_Samsung_4623_1666.html>
which isn't going to be easy to obtain. The CLX-3175FN manual shows
the part as a 4712-001027 but that's a single thermostat, not a
double. Incidentally, on the exploded view of the fuser, there's an
thermistor-NTC which is what probably controls the temperature.

As what is probably and aside I'm also seeing a horizontal band across
the page. It could be off the OPC drum. I'll have to measure the
circumference but it looks about right.

If the fuser wasn't getting hot, but the mechanism was still moving,
then you could have a nice pile of toner piled up in or under the
fuser. Remove and clean.

Note: I don't fix or like Samsung printers.

--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[T i m]

On Mon, 13 Jan 2014 16:51:27 -0800, Jeff Liebermann <jeffl@cruzio.com>
wrote:

On Mon, 13 Jan 2014 23:27:47 +0000, T i m <news@spaced.me.uk> wrote:

No, it was something about cycling the power (that made no difference)
but a Goggle search from that suggested a fuser fault (as one of the
main causes).

Duz this sound familiar?
http://www.fixyourownprinter.com/forums/printer/72871
See 2nd to last comment near bottom of page. That's my favorite fix
of mechanical thermostats.

Hehe! Sfunny, it sounding like there was something 'loose' in one or
both of them but now I know how easy it is to get the fuser out (easy
but fiddly / slightly tedious with all the plugs you need to
disconnect to free the fuser wires (although that might be easier now
<g&gt). I'll try the 'impact reset' test and the good thing is you can
check the result there and then (with yer DMM).

The fuser was indeed cold and (as it turned out) because of what looks
like a thermal switch (or fuse) that had gone o/c. Shorting said
device with some copper wire removed the error message and allowed the
printer to return to a working condition. ;-)

Finding the exact replacement has been a bit of a challenge. This is
the best I can do for now:
http://www.alibaba.com/product-gs/982359539/PT056_Replacement_for_Samsung_4623_1666.html

That's the badger!

>which isn't going to be easy to obtain.

I wonder if they would send me a sample? ;-)

The CLX-3175FN manual shows
the part as a 4712-001027 but that's a single thermostat, not a
double.

Yes, I've since spotted that. The problem is though, if they are both
thermal switches and of different temperatures (the second / higher to
be used more as a failsafe in case the first / normal switch sailed
unsafe) then we don't know which one on mine is still functional?

Incidentally, on the exploded view of the fuser, there's an
thermistor-NTC which is what probably controls the temperature.

Yes, I think I offered / suggested such elsewhere (but didn't know if
it was just to provide feedback to the controller board to say 'Warmed
up'?

As what is probably an aside I'm also seeing a horizontal band across
the page. It could be off the OPC drum. I'll have to measure the
circumference but it looks about right.

If the fuser wasn't getting hot, but the mechanism was still moving,
then you could have a nice pile of toner piled up in or under the
fuser. Remove and clean.

Whilst I didn't check that (in my euphoria re finding the 'fault' and
the potential of checking it again), I'm not sure the print error is
of the right interval for the circumference of the fuser rollers. I
see a horizontal line / mark at about 2" down a sheet of A4 and again
at about the same from the bottom. It may be fading with use.

Note: I don't fix or like Samsung printers.

I've not experienced them till now (normally HPLJ here and still have
a trusty P2015dn on our LAN) and so this is the first one I've looked
at. Hundreds of years ago I worked for Kodak on their microfiche/film
cheque processing machines so I have some experience with this sort of
thing. In comparison though, there was much more 'metal' in the Kodak
stuff. ;-)

Cheers and thanks again for all your help.

T i m

 

[Jeff Liebermann]

On Tue, 14 Jan 2014 08:44:28 +0000, T i m <news@spaced.me.uk> wrote:

Duz this sound familiar?
http://www.fixyourownprinter.com/forums/printer/72871

I'll try the 'impact reset' test and the good thing is you can
check the result there and then (with yer DMM).

I rarely see broken mechanical thermostats. More commonly, on HP
printers, I see accumulated toner residue piled up between the fuser
roller and the thermostat. Usually, there's some type of film between
the two, which prevents scratching the drum. I don't think I've ever
seen a blown thermostat on an HP which makes me wonder if replacing
the 170C thermostat with an identical Samsung part is a good idea.

Yes, I've since spotted that. The problem is though, if they are both
thermal switches and of different temperatures (the second / higher to
be used more as a failsafe in case the first / normal switch sailed
unsafe) then we don't know which one on mine is still functional?

I don't have a schematic, but I'll guess(tm) that they are running
some serious heater current through the thermostat, causing the
contact to possibly arc. A few protective arcs under load, and the
contacts will build up a layer of oxidized copper which makes a fair
insulator. This is the power supply relay contacts of an HP LJII with
a similar problem:
<http://www.learnbydestroying.com/jeffl/pics/drivel/slides/hp-relay.html>
The little back dots make great insulators.

Adding a 2nd thermostat sounds like a retrofit to fix the problem.
There should be a service note on how to do it, somewhere. My
guess(tm) is that two of the single thermostats will fit, if you can
find them.

Incidentally, on the exploded view of the fuser, there's an
thermistor-NTC which is what probably controls the temperature.

Yes, I think I offered / suggested such elsewhere (but didn't know if
it was just to provide feedback to the controller board to say 'Warmed
up'?

I'm sure it goes to the laser engine controller or power supply.
That's the way it's usually done on printers that I'm more familiar
with, such as HP.

I've not experienced them till now (normally HPLJ here and still have
a trusty P2015dn on our LAN)

Retch. The P2015dn and similar printers are my worst nightmare. There
are YouTube videos on how to replace the fuser that should give you a
clue as to how difficult and time consuming that series of printers
are to repair. I have three of that series printers that are on the
shelf awaiting repair of the formatter board, which suffers from lousy
soldering:
<https://www.youtube.com/watch?v=x1acw-7kMws>
<https://www.youtube.com/watch?v=F1q2lmoLUzc>

>Cheers and thanks again for all your help.

Good luck and I still don't like Samsung printers.

--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[T i m]

On Tue, 14 Jan 2014 09:48:15 -0800, Jeff Liebermann <jeffl@cruzio.com>
wrote:

On Tue, 14 Jan 2014 08:44:28 +0000, T i m <news@spaced.me.uk> wrote:

Duz this sound familiar?
http://www.fixyourownprinter.com/forums/printer/72871

I'll try the 'impact reset' test and the good thing is you can
check the result there and then (with yer DMM).

I rarely see broken mechanical thermostats. More commonly, on HP
printers, I see accumulated toner residue piled up between the fuser
roller and the thermostat. Usually, there's some type of film between
the two, which prevents scratching the drum. I don't think I've ever
seen a blown thermostat on an HP which makes me wonder if replacing
the 170C thermostat with an identical Samsung part is a good idea.

Unfortunately without knowing the function / specification of both
parts I'm not sure I have a choice? By that I mean if I was doing such
for someone else, rather than what I might do for myself.

Yes, I've since spotted that. The problem is though, if they are both
thermal switches and of different temperatures (the second / higher to
be used more as a failsafe in case the first / normal switch sailed
unsafe) then we don't know which one on mine is still functional?

I don't have a schematic,

I have some block / logic diagrams but no schematic. ;-(

It does say this of the fuser though ... (in case it helps).

"....Fuser Ass’y
This unit consists of Heat Roller, a Thermostat and a Thermistor. It
melts and fuses the toner, transferred
by the transfer roller onto the paper, by applying pressure and high
temperature to complete printing job.
* Heat Lamp : Kunckle Type
* Fusing system : 3-Roll Fusing type
- Heat roller : Pipe type (Lamp inside)
- Pressure roller
- Pressure roller Shaft
* Thermistor - Temperature-Measuring Device
* Thermostat - Critical Temperature-Detecting Device
* The life span – 100k(black)/color(25k)

Thermostat
When a heat lamp is overheated, a Thermostat cuts off the main power
to prevent over-heating.
- Non-Contact type Thermostat"

but I'll guess(tm) that they are running
some serious heater current through the thermostat, causing the
contact to possibly arc. A few protective arcs under load, and the
contacts will build up a layer of oxidized copper which makes a fair
insulator.

Understood.

This is the power supply relay contacts of an HP LJII with
a similar problem:
http://www.learnbydestroying.com/jeffl/pics/drivel/slides/hp-relay.html
The little back dots make great insulators.

Ouch.

Adding a 2nd thermostat sounds like a retrofit to fix the problem.

Not the problem of going o/c I assume?

There should be a service note on how to do it, somewhere. My
guess(tm) is that two of the single thermostats will fit, if you can
find them.

Oh, I'm sure they / I could cover that, if I can find the right fit
and spec parts.

Incidentally, on the exploded view of the fuser, there's an
thermistor-NTC which is what probably controls the temperature.

Yes, I think I offered / suggested such elsewhere (but didn't know if
it was just to provide feedback to the controller board to say 'Warmed
up'?

I'm sure it goes to the laser engine controller or power supply.
That's the way it's usually done on printers that I'm more familiar
with, such as HP.

The thermistor goes back to the main controller board that is for
sure. I need to have a closer look at the PSU to see if there are any
other connectors from the other boards. Otherwise there is only mains
in and the outputs to the rest of the unit and the fuser. Would the
fuser normally be running at full temperature when the (a) printer was
at idle?

I've not experienced them till now (normally HPLJ here and still have
a trusty P2015dn on our LAN)

Retch. The P2015dn and similar printers are my worst nightmare.

Oh. ;-( Well, I bought it cheap s/h as I wanted a networked b/w
duplex laser and so far <touching wood> it's been ok.

What would you recommend then to cover a similar SOHO, networked
(wired) duplex mono role then Jeff?

There
are YouTube videos on how to replace the fuser that should give you a
clue as to how difficult and time consuming that series of printers
are to repair.

I'm guessing that like many things (including cars) these days they
are designed to be disposable. ;-(

I have three of that series printers that are on the
shelf awaiting repair of the formatter board, which suffers from lousy
soldering:
https://www.youtube.com/watch?v=x1acw-7kMws
https://www.youtube.com/watch?v=F1q2lmoLUzc

Luckily I have a mate with all the reflow gear. ;-)

Cheers and thanks again for all your help.

Good luck and I still don't like Samsung printers.

Thanks and ;-)

Oh, I contacted the supplier of the thermostat pair you kindly found
me and they have replied saying 5 off (minimum quantity) will cost me
80 USD delivered. Now, that's less than the cost of a new fuser but at
least with a new fuser I get a new fuser (as well). ;-)

I've set the printer to idle after 5 mins and will plug it into a
power monitor so I can check to see what sort of current /
background_current it draws then decide from there if I'd want to
leave it on 24/7 or not (as is).

I have 2 x HPLJ 4's that I'm not sure what to do with. They are big,
heavy, non-duplex and neither work properly (electronics faults). I
understand they are (were?) workhorses but they are just so big by
todays SOHO b/w laser standards (one has a JetDirect card fitted).

Cheers, T i m

p.s. I can't seem to get this Samsung to connect via WiFi. It 'sees'
al the local WiFi networks but doesn't want to connect to any (all
mine). The thing that worries me is that although I put the WPA
passphrase in in lower case it displays it in the status printout in
upper?

 

[Jeff Liebermann]

On Tue, 14 Jan 2014 21:21:45 +0000, T i m <news@spaced.me.uk> wrote:

>I have some block / logic diagrams but no schematic. ;-(

See if the fuser heater current goes through the thermostat. I
suspect that it does, which means the thermostat has to disconnect
under load. Nice way to create a small arc.

>* Heat Lamp : Kunckle Type

A what?

Thermostat
When a heat lamp is overheated, a Thermostat cuts off the main power
to prevent over-heating.

Main power as in the AC line power? I doubt that. Probably just the
fuser heater power.

Adding a 2nd thermostat sounds like a retrofit to fix the problem.

Not the problem of going o/c I assume?

My wild guess(tm) is that the 170C was too low in temperature to stay
closed while the printer was being used as a printing press. The
manufacturer usually recommends a duty cycle, such as 20 mins print,
10 minutes rest, etc which of course, nobody follows. The thermostat
would probably open a few times during such heavy duty printing. The
thermostats are not meant to survive too many such cycles. Rather
than welding the contacts shut, which would be a safety problem, like
a common household circuit breaker, they're made to open at ever
decreasing temperatures, eventually resulting in a permanent open
circuit. Note: this is a guess, this is only a guess.

Would the
fuser normally be running at full temperature when the (a) printer was
at idle?

No. Most laser printers have 3 or 4 levels of power savings. Then
printing, the fuser heater power is full blast. Between print jobs,
usually for about 10 minutes, the power is at about 30% of full blast.
If the printer goes into standby, the fuser power is at about 5-10%
which is just enough to get the first page printed reasonably fast and
avoid major inrush current. In shutdown, the fuser power is totally
off. I have no idea what Samsung does in this printer.

What would you recommend then to cover a similar SOHO, networked
(wired) duplex mono role then Jeff?

I like the HP 2300DTN printer.
<http://h20566.www2.hp.com/portal/site/hpsc/public/psi/manualsResults/?cc=us&sp4ts.oid=238800>
I own 3 of them, and have resold or arm twisted customers into buying
approximately 15 of them. The first page comes out in about 3
seconds. Duplex printing is handy to save paper, but is admittedly
slow. However, like all HP printers, these have a lifetime shortening
feature which I believe HP has ignored because it causes obscure late
term failures that sell many replacement printers. Here's the fix:
<http://www.learnbydestroying.com/jeffl/hp2200/hp2200.html>
I've also found the same sticky solenoid problem in all HP printers of
the same vintage (2200, 2230, 4100, 4150, 4200, 4250, 4300, etc).
Also, you might have problems with magnetized solenoids:
<http://www.learnbydestroying.com/jeffl/crud/hp2200-solenoid.wmv>
You'll need an antique 1/4" magnetic tape bulk eraser to fix that.
Otherwise, the 2300dtn have been a great printer.

I'm guessing that like many things (including cars) these days they
are designed to be disposable. ;-(

Todays design methodology is actually fairly simple and somewhat
economical. The manufacturer sets a target lifetime for the product.
He then cost reduces components and assembly techniques until
literally everything fails at the same time, somewhat after the target
lifetime. Anything that lasts longer than the target lifetime is
considered a waste of money and is further cost reduced. I can
critique HP's latest laser printer offerings on this basis, but I'm
late for a paying appointment.

>Luckily I have a mate with all the reflow gear. ;-)

I have a hot air SMT desoldering station. It doesn't work. The main
problem is that when the solder is hot enough to reflow, the blowing
air pushes the parts out of position. An IR reflow station is what
you want. However, I pizza oven or electric toaster oven is good
enough.
<https://www.sparkfun.com/tutorials/60>

Oh, I contacted the supplier of the thermostat pair you kindly found
me and they have replied saying 5 off (minimum quantity) will cost me
80 USD delivered. Now, that's less than the cost of a new fuser but at
least with a new fuser I get a new fuser (as well). ;-)

I think I can find a replacement single thermostat in the US for much
less. Later tonite...

>I have 2 x HPLJ 4's that I'm not sure what to do with.

eWaste.

p.s. I can't seem to get this Samsung to connect via WiFi. It 'sees'
al the local WiFi networks but doesn't want to connect to any (all
mine). The thing that worries me is that although I put the WPA
passphrase in in lower case it displays it in the status printout in
upper?

Temporarily clear the WPA encryption key from the wireless router and
see if it will connect with no pass phrase. If that works, try
entering a simple WPA2-AES pass phrase and see if that works. The
usual problem is that some devices enforce the 8 character minimum
pass phrase length, while others ignore it. The other common problem
are Apple Airport base stations that need a firmware update in order
to coexist with other devices. Yet another are web forms that don't
like spaces in the pass phrase. The encryption key can have spaces
but the web form transfers the spaces as garbage. Isn't compatibility
great fun?

Gone...


--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[T i m]

On Tue, 14 Jan 2014 15:30:00 -0800, Jeff Liebermann <jeffl@cruzio.com>
wrote:

On Tue, 14 Jan 2014 21:21:45 +0000, T i m <news@spaced.me.uk> wrote:

I have some block / logic diagrams but no schematic. ;-(

See if the fuser heater current goes through the thermostat. I
suspect that it does, which means the thermostat has to disconnect
under load. Nice way to create a small arc.

It does, both, they are in series with the heater / lamp.

* Heat Lamp : Kunckle Type

A what?

;-) Pass!

Thermostat
When a heat lamp is overheated, a Thermostat cuts off the main power
to prevent over-heating.

Main power as in the AC line power? I doubt that. Probably just the
fuser heater power.

Yup.

Adding a 2nd thermostat sounds like a retrofit to fix the problem.

Not the problem of going o/c I assume?

My wild guess(tm) is that the 170C was too low in temperature to stay
closed while the printer was being used as a printing press. The
manufacturer usually recommends a duty cycle, such as 20 mins print,
10 minutes rest, etc which of course, nobody follows.

Hehe.

The thermostat
would probably open a few times during such heavy duty printing. The
thermostats are not meant to survive too many such cycles. Rather
than welding the contacts shut, which would be a safety problem, like
a common household circuit breaker, they're made to open at ever
decreasing temperatures, eventually resulting in a permanent open
circuit. Note: this is a guess, this is only a guess.

Ok ...

Would the
fuser normally be running at full temperature when the (a) printer was
at idle?

No. Most laser printers have 3 or 4 levels of power savings. Then
printing, the fuser heater power is full blast. Between print jobs,
usually for about 10 minutes, the power is at about 30% of full blast.
If the printer goes into standby, the fuser power is at about 5-10%
which is just enough to get the first page printed reasonably fast and
avoid major inrush current. In shutdown, the fuser power is totally
off. I have no idea what Samsung does in this printer.

Well, I've set it to 'sleep' after 5 mins and after 30 mins you can
still feel warmth coming out of the paper exit port (I assume that to
also be a thermal vent for the fuser).

What would you recommend then to cover a similar SOHO, networked
(wired) duplex mono role then Jeff?

I like the HP 2300DTN printer.

<Googles> It looks fairly 'chunky'?

http://h20566.www2.hp.com/portal/site/hpsc/public/psi/manualsResults/?cc=us&sp4ts.oid=238800
I own 3 of them, and have resold or arm twisted customers into buying
approximately 15 of them. The first page comes out in about 3
seconds. Duplex printing is handy to save paper, but is admittedly
slow. However, like all HP printers, these have a lifetime shortening
feature which I believe HP has ignored because it causes obscure late
term failures that sell many replacement printers.

Oh?

Here's the fix:
http://www.learnbydestroying.com/jeffl/hp2200/hp2200.html

Nice.

I've also found the same sticky solenoid problem in all HP printers of
the same vintage (2200, 2230, 4100, 4150, 4200, 4250, 4300, etc).
Also, you might have problems with magnetized solenoids:
http://www.learnbydestroying.com/jeffl/crud/hp2200-solenoid.wmv
You'll need an antique 1/4" magnetic tape bulk eraser to fix that.

Got one of those. ;-)

Otherwise, the 2300dtn have been a great printer.

I'm guessing that like many things (including cars) these days they
are designed to be disposable. ;-(

Todays design methodology is actually fairly simple and somewhat
economical. The manufacturer sets a target lifetime for the product.
He then cost reduces components and assembly techniques until
literally everything fails at the same time, somewhat after the target
lifetime. Anything that lasts longer than the target lifetime is
considered a waste of money and is further cost reduced. I can
critique HP's latest laser printer offerings on this basis, but I'm
late for a paying appointment.

Ok.

Luckily I have a mate with all the reflow gear. ;-)

I have a hot air SMT desoldering station. It doesn't work. The main
problem is that when the solder is hot enough to reflow, the blowing
air pushes the parts out of position. An IR reflow station is what
you want. However, I pizza oven or electric toaster oven is good
enough.
https://www.sparkfun.com/tutorials/60

Yeah, that's the sort of thing my mate has built / modded / bought
etc.

Oh, I contacted the supplier of the thermostat pair you kindly found
me and they have replied saying 5 off (minimum quantity) will cost me
80 USD delivered. Now, that's less than the cost of a new fuser but at
least with a new fuser I get a new fuser (as well). ;-)

I think I can find a replacement single thermostat in the US for much
less. Later tonite...

Oh, cool, thanks (but aren't we still unsure what role both devices
covered? Stat+backup stat. Stat+Overtemp Stat? Stat+Thermal fuse?

I have 2 x HPLJ 4's that I'm not sure what to do with.

eWaste.

Hmmm, shame.

p.s. I can't seem to get this Samsung to connect via WiFi. It 'sees'
al the local WiFi networks but doesn't want to connect to any (all
mine). The thing that worries me is that although I put the WPA
passphrase in in lower case it displays it in the status printout in
upper?

Temporarily clear the WPA encryption key from the wireless router and
see if it will connect with no pass phrase. If that works, try
entering a simple WPA2-AES pass phrase and see if that works. The
usual problem is that some devices enforce the 8 character minimum
pass phrase length, while others ignore it.

We have 8+ on all of them. I can do as you suggest but with a spare
router.

The other common problem
are Apple Airport base stations that need a firmware update in order
to coexist with other devices. Yet another are web forms that don't
like spaces in the pass phrase. The encryption key can have spaces
but the web form transfers the spaces as garbage. Isn't compatibility
great fun?

Isn't it just (not). ;-)

Gone...

<looks around>

Whoah, where did Jeff go ...?

Cheers, T i m

 

[Jeff Liebermann]

On Wed, 15 Jan 2014 01:41:27 +0000, T i m <news@spaced.me.uk> wrote:

My wild guess(tm) is that the 170C was too low in temperature to stay
closed while the printer was being used as a printing press. The
manufacturer usually recommends a duty cycle, such as 20 mins print,
10 minutes rest, etc which of course, nobody follows.

Hehe.

Before electronic filing, my tax preparer customers would run their
laser printers almost full time during late tax season. Five inch
thick returns were common. A floor fan blowing on the printer was
also common. All of them went through the same exercise. They would
buy a cheap laser printer, run it like a printing press, destroy it,
and then buy something more suitable.

HP is unique in that it has a built in safety feature to prevent
overheating and over use. It's the sticky solenoid and foam rubber
pad I mentioned in a previous rant. When the machine is cold, the
solenoids work normally. However, as the solenoid becomes hot from
use, the glue and foam rubber pad melts, causing the solenoid armature
to stick to the frame. The timing error usually produces a paper jam
which offers the user a chance to slow down while practicing
profanity.

There has been some suggestion the sticky foam safety feature is not
intentional, but I suspect otherwise. HP has used exactly the same
design for their sticky solenoid safety feature since the HP LJII
which suggests that it's a successful method of controlling the
printing duty cycle.

Well, I've set it to 'sleep' after 5 mins and after 30 mins you can
still feel warmth coming out of the paper exit port (I assume that to
also be a thermal vent for the fuser).

I use a Kill-a-watt AC power meter to measure power consumption in
various states. Occasionally, my measurements agree with the data
sheet. You might want to measure the standby and power save power
consumption, which offer clues as to the fuser power consumption.

I like the HP 2300DTN printer.

Googles> It looks fairly 'chunky'?

It's bigger than your P2025 but not as big as a production printer
such as a 4150, 4250, or 4300. Certainly smaller than an 8000 series
printer. Two of mine show about 80,000 pages. The other is at about
10,000 because I replaced the formatter board. I replace most of the
rubber parts when I rebuild a printer. I get about 5000 pages per
toner cart. If you want better, you'll have to live with bigger.

I think I can find a replacement single thermostat in the US for much
less. Later tonite...

Oh, cool, thanks (but aren't we still unsure what role both devices
covered? Stat+backup stat. Stat+Overtemp Stat? Stat+Thermal fuse?

Yep. If my guess is correct about thermostat cycling due to excessive
use, putting in the wrong thermostat will make it worse if set to a
lower temperature, or melt the fuser if set to a higher temperature.
At this point, I would so some measuring with an IR thermometer or
thermocouple. My guess(tm) is that the operating temperature is too
close to the thermostat temperature.

--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[T i m]

On Wed, 15 Jan 2014 09:08:51 -0800, Jeff Liebermann <jeffl@cruzio.com>
wrote:

On Wed, 15 Jan 2014 01:41:27 +0000, T i m <news@spaced.me.uk> wrote:

My wild guess(tm) is that the 170C was too low in temperature to stay
closed while the printer was being used as a printing press. The
manufacturer usually recommends a duty cycle, such as 20 mins print,
10 minutes rest, etc which of course, nobody follows.

Hehe.

Before electronic filing, my tax preparer customers would run their
laser printers almost full time during late tax season. Five inch
thick returns were common.

Wow.

A floor fan blowing on the printer was
also common. All of them went through the same exercise. They would
buy a cheap laser printer, run it like a printing press, destroy it,
and then buy something more suitable.

The guy opposite has done similar with a few small Brother and Samsung
mono lasers. I think he has since been given something bigger. ;-)

HP is unique in that it has a built in safety feature to prevent
overheating and over use. It's the sticky solenoid and foam rubber
pad I mentioned in a previous rant. When the machine is cold, the
solenoids work normally. However, as the solenoid becomes hot from
use, the glue and foam rubber pad melts, causing the solenoid armature
to stick to the frame. The timing error usually produces a paper jam
which offers the user a chance to slow down while practicing
profanity.

Hehe.

There has been some suggestion the sticky foam safety feature is not
intentional, but I suspect otherwise.

<weg>

HP has used exactly the same
design for their sticky solenoid safety feature since the HP LJII
which suggests that it's a successful method of controlling the
printing duty cycle.

;-)

Well, I've set it to 'sleep' after 5 mins and after 30 mins you can
still feel warmth coming out of the paper exit port (I assume that to
also be a thermal vent for the fuser).

I use a Kill-a-watt AC power meter to measure power consumption in
various states. Occasionally, my measurements agree with the data
sheet. You might want to measure the standby and power save power
consumption, which offer clues as to the fuser power consumption.

Approximate values.
Warm-up power mostly 900W for about 30 seconds.
12 or 900W on a 7:1 duty cycle after that.
After 5 mins it sleeps to a constant 10W.

Printing 3 colour pages from standby:
Going from 45 (motor running) to 900+W (fuser on + motor running +
paper handling) for the duration of the print process then back to 12
- 900 (7:1 duty cycle) till standby.

I like the HP 2300DTN printer.

Googles> It looks fairly 'chunky'?

It's bigger than your P2025 but not as big as a production printer
such as a 4150, 4250, or 4300. Certainly smaller than an 8000 series
printer. Two of mine show about 80,000 pages.

!

My (new to me) Samsung:
Total Page Count : 3260 / 1976 Page(s) (Color/Mono)
Toner Page Count :
( Yellow / Magenta / Cyan / Black ) ( 998 / 995 / 994 /
731 ) Page(s)
Fuser Life : 14995 Page(s)
Transfer Roller Life : 5223 Page(s)
Tray Roller Life : 5236 Page(s)
Total Image Count : 15040 Image(s)
Imaging Unit Life : 15040 Image(s)
Transfer Belt Life : 15040 Image(s)
ADF Scan Page Count : 176 Page(s)
Platen Scan Page Count : 187 Page(s)

.... an I think it's done that over a few years.

The other is at about
10,000 because I replaced the formatter board. I replace most of the
rubber parts when I rebuild a printer. I get about 5000 pages per
toner cart. If you want better, you'll have to live with bigger.

Quite.

I think I can find a replacement single thermostat in the US for much
less. Later tonite...

Oh, cool, thanks (but aren't we still unsure what role both devices
covered? Stat+backup stat. Stat+Overtemp Stat? Stat+Thermal fuse?

Yep. If my guess is correct about thermostat cycling due to excessive
use, putting in the wrong thermostat will make it worse if set to a
lower temperature, or melt the fuser if set to a higher temperature.
At this point, I would so some measuring with an IR thermometer or
thermocouple. My guess(tm) is that the operating temperature is too
close to the thermostat temperature.

So, you feel the temperature is being controlled via the thermistor <>
controller <> PSU rather than the stats? That they are just there for
over temp?

I guess if I pop the side off (now I know how) I can (carefully, 240V)
monitor the feed to the fuser heater and see if it's 'switched' at
that point. If it isn't yet the machine current is still fluctuating
then it must be the stat that is managing the temperature (rightly or
wrongly etc)?

Cheers, T i m

p.s. The guy who can supply the stats can also supply the complete new
fuser and I'm currently awaiting his reply on that.