Homebrew_PCBs

Hi Stefan,

My buddy gave me an old (about 3 years) laser printer. He believe the
fuser is good so I might have a fuser to hack! I will start pulling
the printer apart tonight if I don't get called out of town again. I
recall you mentioning certain critical parts I need to keep from the
rest of the printer so I won't butcher it up too bad. Can you refresh
my memory as to what else I need from the printer?

Also, what sort of motor did you use to drive your fuser? I remember
you saying it takes about 1 minute to pass a board through, so I am
guessing you are using some sort of gear motor.

Thanks!

Chris

On Fri, 02 Dec 2005 14:47:10 +0100, lcdpublishing
<lcdpublishing@...> wrote:

> Hi Stefan,
>
>
> My buddy gave me an old (about 3 years) laser printer. He believe the
>
> fuser is good so I might have a fuser to hack! I will start pulling
>
> the printer apart tonight if I don't get called out of town again. I
>
> recall you mentioning certain critical parts I need to keep from the
>
> rest of the printer so I won't butcher it up too bad. Can you refresh
>
> my memory as to what else I need from the printer?
>
>
> Also, what sort of motor did you use to drive your fuser? I remember
>
> you saying it takes about 1 minute to pass a board through, so I am
>
> guessing you are using some sort of gear motor.
>
>
> Thanks!
>
>
> Chris

There must be a triac in there and a optocoupler, which are useful. But
you could also use any solid state relais to make the thermostat. If you
follow the power wires of the fuser (the ones that go to the lamp inside
the roller) those will lead you to the interesting PCB. Also keep the
thermistor with the fuser (two thin wires coming out of it). You just need
to keep the thermistor with the wires, the electronics using it are
usually no good.

For a motor i use a chicken grill motor. Mine is a belt-drive with about 2
to 1 ratio, but direct drive would be OK, especially with the smaller
diameter rollers of a fuser.

I have the schematic for the simple thermostat somewhere, i'll dig it
out...

You'll want some type of thermometer that can measure the temperature of
the hot fuser roller to set it up, i suggest a thermocouple sensor on a
multimeter with temp. range or maybe a optical thermometer (although i
dunno how well they work on the fuser surface).
You can use browning of paper and stuff, but it's really better to know
for sure.

ST

There are a number of large components on the Circuit board near the
connection point to the fuser. Several, what I believe are solid
state relays - a triac w/heatsink (I think), some transformers etc.

The optocoupler I am not sure of. There are a number of opto-
switches (the slotted devices used to sense something between
them). I don't think this is what you are referring to though so I
will study the PCB some more to see if I Can find something that
looks like an Optoisolater chip.

On the fuser itself, there are the power wires going in one end of
the unit. On the opposite end, there are two groups of wires going
in - I am assuming one of those two sets of wires is the
thermostat. I didn't want to mess with it too much till I found out
what I should be keeping and such.

The unit seems to accept a PCB board without trouble and by turning
the shaft by hand, it will pass right through.

I do have a photo-type thermometer that I use all the time around
the shop - goes up to 400 degrees F so that should work good. I
will have to scrounge a motor somewhere. It is winter here now so
the retailers have all the grill stuff packed away - but, with
Christmas getting close, as soon as that is over, the summer stuff
will be back on the shelves again.

> There must be a triac in there and a optocoupler, which are

useful. But

> you could also use any solid state relais to make the thermostat.

If you

> follow the power wires of the fuser (the ones that go to the lamp

inside

> the roller) those will lead you to the interesting PCB. Also keep

the

> thermistor with the fuser (two thin wires coming out of it). You

just need

> to keep the thermistor with the wires, the electronics using it

are

> usually no good.
>
> For a motor i use a chicken grill motor. Mine is a belt-drive with

about 2

> to 1 ratio, but direct drive would be OK, especially with the

smaller

> diameter rollers of a fuser.
>
> I have the schematic for the simple thermostat somewhere, i'll dig

it

> out...
>
> You'll want some type of thermometer that can measure the

temperature of

> the hot fuser roller to set it up, i suggest a thermocouple sensor

on a

> multimeter with temp. range or maybe a optical thermometer

(although i

> dunno how well they work on the fuser surface).
> You can use browning of paper and stuff, but it's really better to

know

> for sure.
>
> ST
>

What model/brand printer is that?

About the solid state relais, the right triac must be right between one of
the fuser lamp wires and mains power, so if you follow the wires you must
hit it. Check the part number if it is a triac to be sure. By following
the third leg of the triac (usually with a thinner trace going to it) you
must hit the optocoupler. Best to take out the whole board, there's
usually a resistor between opto and mains you'll need. Ideally trace the
circuit from the opto output the the triac and associated components so
you know how you need to assemble it later on. The triac mightn't have a
heatsink.

You'll also need some form of low power DC supply like 5V or 12V or
whatever for the thermostat, so if there are components in there you like,
take them.

There's a old writeup about the fuser at
<http://trethan.at.tf/pub/fuser/fuser_as_laminator.html>, it's over a year
old and full of typos, maybe i'll get around to update it one of these
days. But basically you see the most simple circuit you need to put on the
opto input, the opto output and triac stuff is best left like it was in
the printer.

ST


On Fri, 02 Dec 2005 18:57:10 +0100, lcdpublishing
<lcdpublishing@...> wrote:

> There are a number of large components on the Circuit board near the
>
> connection point to the fuser. Several, what I believe are solid
>
> state relays - a triac w/heatsink (I think), some transformers etc.
>
>
> The optocoupler I am not sure of. There are a number of opto-
>
> switches (the slotted devices used to sense something between
>
> them). I don't think this is what you are referring to though so I
>
> will study the PCB some more to see if I Can find something that
>
> looks like an Optoisolater chip.
>
>
> On the fuser itself, there are the power wires going in one end of
>
> the unit. On the opposite end, there are two groups of wires going
>
> in - I am assuming one of those two sets of wires is the
>
> thermostat. I didn't want to mess with it too much till I found out
>
> what I should be keeping and such.
>
>
> The unit seems to accept a PCB board without trouble and by turning
>
> the shaft by hand, it will pass right through.
>
>
> I do have a photo-type thermometer that I use all the time around
>
> the shop - goes up to 400 degrees F so that should work good. I
>
> will have to scrounge a motor somewhere. It is winter here now so
>
> the retailers have all the grill stuff packed away - but, with
>
> Christmas getting close, as soon as that is over, the summer stuff
>
> will be back on the shelves again.

Hi Stefan,

THe printer is an HP2200dse.

I will trace out the traces backwards from the power connect for the
fuser. I looked over you schematic and I think I see what is going
on and what to look for. If needed, I will post some pictures of
the PCB if I get lost, but I think I understand it.

BTW, is this isolator needed for the same reason I needed one on my
spindle driver that fried my computer last year?




--- In Homebrew_PCBs@yahoogroups.com, "Stefan Trethan"
<stefan_trethan@g...> wrote:

>
> What model/brand printer is that?
>
> About the solid state relais, the right triac must be right

between one of

> the fuser lamp wires and mains power, so if you follow the wires

you must

> hit it. Check the part number if it is a triac to be sure. By

following

> the third leg of the triac (usually with a thinner trace going to

it) you

> must hit the optocoupler. Best to take out the whole board,

there's

> usually a resistor between opto and mains you'll need. Ideally

trace the

> circuit from the opto output the the triac and associated

components so

> you know how you need to assemble it later on. The triac mightn't

have a

> heatsink.
>
> You'll also need some form of low power DC supply like 5V or 12V

or

> whatever for the thermostat, so if there are components in there

you like,

> take them.
>
> There's a old writeup about the fuser at
> <http://trethan.at.tf/pub/fuser/fuser_as_laminator.html>, it's

over a year

> old and full of typos, maybe i'll get around to update it one of

these

> days. But basically you see the most simple circuit you need to

put on the

> opto input, the opto output and triac stuff is best left like it

was in

> the printer.
>
> ST
>
>
> On Fri, 02 Dec 2005 18:57:10 +0100, lcdpublishing
> <lcdpublishing@y...> wrote:
>
> > There are a number of large components on the Circuit board near

the

> >
> > connection point to the fuser. Several, what I believe are solid
> >
> > state relays - a triac w/heatsink (I think), some transformers

etc.

> >
> >
> > The optocoupler I am not sure of. There are a number of opto-
> >
> > switches (the slotted devices used to sense something between
> >
> > them). I don't think this is what you are referring to though

so I

> >
> > will study the PCB some more to see if I Can find something that
> >
> > looks like an Optoisolater chip.
> >
> >
> > On the fuser itself, there are the power wires going in one end

of

> >
> > the unit. On the opposite end, there are two groups of wires

going

> >
> > in - I am assuming one of those two sets of wires is the
> >
> > thermostat. I didn't want to mess with it too much till I found

out

> >
> > what I should be keeping and such.
> >
> >
> > The unit seems to accept a PCB board without trouble and by

turning

> >
> > the shaft by hand, it will pass right through.
> >
> >
> > I do have a photo-type thermometer that I use all the time around
> >
> > the shop - goes up to 400 degrees F so that should work good. I
> >
> > will have to scrounge a motor somewhere. It is winter here now

so

> >
> > the retailers have all the grill stuff packed away - but, with
> >
> > Christmas getting close, as soon as that is over, the summer

stuff

> >
> > will be back on the shelves again.
>

On Fri, 02 Dec 2005 19:40:20 +0100, lcdpublishing
<lcdpublishing@...> wrote:

>
>
> BTW, is this isolator needed for the same reason I needed one on my
>
> spindle driver that fried my computer last year?

Yea, more or less. it isolated the thermisotor and pot and supply from
mains, which isn't all designed to be at that potential, 'specially the
thermistor. Often it will be a phototriac which does the firing of the
triac the right way without hassle at a zero crossing.

ST

Stefan, This one you will appreciate - please read.

I was looking over the PCB for the printer trying to find the opto
and the triac. I am studying it like crazy - components on one
side, traces on back side trying to figure it out. It's not a dense
board by any means, I am just stupid. Anyway, to figure out what is
what, I would go to mouser and digikey and type in the part numbers
of the various components - didn't help at all.

So, while just staring at the PCB I noticed something interesting in
the legends - the board is divided into two sections -primary and
secondary. There are three, 4 pin DIPs bridging that outline and
one big transformer. After thinking about that for a moment, I
realized that those 3 small ICs are going to be the optos which
isolate the primary from the secondary !

Kinda neat how HP laid out the board like that. I will try to get a
photo of it.

chris



--- In Homebrew_PCBs@yahoogroups.com, "Stefan Trethan"
<stefan_trethan@g...> wrote:

>
> On Fri, 02 Dec 2005 19:40:20 +0100, lcdpublishing
> <lcdpublishing@y...> wrote:
>
> >
> >
> > BTW, is this isolator needed for the same reason I needed one on

my

> >
> > spindle driver that fried my computer last year?
>
>
> Yea, more or less. it isolated the thermisotor and pot and supply

from

> mains, which isn't all designed to be at that

potential, 'specially the

> thermistor. Often it will be a phototriac which does the firing of

the

> triac the right way without hassle at a zero crossing.
>
> ST
>

It's good that you amazed by it, but a lot of boards are laid out in that
way with the sides labeled.
The optos are probably feedback for the SMPS, one might just be the one
controlling the fuser.
You'll probably also find a ferrite transformer or two straddling this
demarcation line.

When checking part numbers, don't use suppliers pages use google or
datasheet search pages they'll find much more.

ST



On Sat, 03 Dec 2005 14:51:42 +0100, lcdpublishing
<lcdpublishing@...> wrote:

> Stefan, This one you will appreciate - please read.
>
>
> I was looking over the PCB for the printer trying to find the opto
>
> and the triac. I am studying it like crazy - components on one
>
> side, traces on back side trying to figure it out. It's not a dense
>
> board by any means, I am just stupid. Anyway, to figure out what is
>
> what, I would go to mouser and digikey and type in the part numbers
>
> of the various components - didn't help at all.
>
>
> So, while just staring at the PCB I noticed something interesting in
>
> the legends - the board is divided into two sections -primary and
>
> secondary. There are three, 4 pin DIPs bridging that outline and
>
> one big transformer. After thinking about that for a moment, I
>
> realized that those 3 small ICs are going to be the optos which
>
> isolate the primary from the secondary !
>
>
> Kinda neat how HP laid out the board like that. I will try to get a
>
> photo of it.
>
>
> chris
>