Installing & using a LaserJet 4 Plus duplexer

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Jonathan Sachs

A few weeks ago I asked about the advisability of buying a used duplexer,
and the responses were encouraging. In another forum I asked about
installation, since used gadgets tend to come without instructions, and I
was assured that there is nothing to it: put the printer on top, plug it in,
and go.

My duplexer just arrived, and I'm finding that it isn't quite as simple to
use as that.

There are "instructions" printed on the bottom plate of the duplexer's paper
tray. Unfortunately they are the type of pictographic instructions that are
comprehensible only to people who can't read.

As far as I can interpret them, here is what I'm supposed to do.

1. Insert the rear and right paper detents in the appropriate positions for
the length and width of the paper to be used.

2. Insert paper in the tray. (I thought this was a holding tray for paper
that has been printed on one side but has not yet been printed on the other.
The pictograph seems to indicate otherwise, but if I understand it
correctly, I'm baffled about where half-printed paper actually goes.)

3. Press the paper down to ensure that all of the sheets are underneath the
retaining clip in the left front corner of the tray.

4. Adjust the left-hand knob at the front of the paper tray. (What to adjust
it for unclear -- it's labeled with a two-headed arrow, but there is no hint
about what it does.)

5. Adjust the right-hand knob at the front of the paper tray. (This one is
clear; it has positions labeled Letter, Legal, Exec, and A4.)

6. (Presumably, not shown in the "instructions"): push the tray in.

Can anyone clarify what I'm supposed to do to use this thing, once I install
it?
 
Jonathan said:
A few weeks ago I asked about the advisability of buying a used duplexer,
and the responses were encouraging. In another forum I asked about
installation, since used gadgets tend to come without instructions, and I
was assured that there is nothing to it: put the printer on top, plug it in,
and go.

My duplexer just arrived, and I'm finding that it isn't quite as simple to
use as that.

There are "instructions" printed on the bottom plate of the duplexer's paper
tray. Unfortunately they are the type of pictographic instructions that are
comprehensible only to people who can't read.

As far as I can interpret them, here is what I'm supposed to do.

1. Insert the rear and right paper detents in the appropriate positions for
the length and width of the paper to be used.

2. Insert paper in the tray. (I thought this was a holding tray for paper
that has been printed on one side but has not yet been printed on the other.
The pictograph seems to indicate otherwise, but if I understand it
correctly, I'm baffled about where half-printed paper actually goes.)

3. Press the paper down to ensure that all of the sheets are underneath the
retaining clip in the left front corner of the tray.

4. Adjust the left-hand knob at the front of the paper tray. (What to adjust
it for unclear -- it's labeled with a two-headed arrow, but there is no hint
about what it does.)

5. Adjust the right-hand knob at the front of the paper tray. (This one is
clear; it has positions labeled Letter, Legal, Exec, and A4.)

6. (Presumably, not shown in the "instructions"): push the tray in.

Can anyone clarify what I'm supposed to do to use this thing, once I install
it?
Click to expand...
Can your email account take a pretty large attachment?


About 4.5 megs


HP LJ 4 4plus 4m 4m plus 5 5m 5n Service Manual.Pdf


Reply by e-mail and don't forget to CUTHERE in the address.

Jim
 
Can your email account take a pretty large attachment?

About 4.5 megs

HP LJ 4 4plus 4m 4m plus 5 5m 5n Service Manual.Pdf
Click to expand...

If not, I have one he can download.

But it won't magically turn a 500 sheet paper tray into a duplexer.
 
But it won't magically turn a 500 sheet paper tray into a duplexer.
Click to expand...

You're right. I didn't realize what was wrong because I haven't seen a
duplexer before, but this ain't it. Back to the seller I go.
 
Further adventures with buying a duplexer...

I contacted the seller and informed him that he had unintentionally shipped
a lower paper cassette instead of a duplexer. He was very cooperative and
shipped the duplexer immediately. We agreed that the cost of returning the
lower paper cassette exceeded its value, so I would keep it.

The duplexer arrived today. I installed it with the lower paper cassette.
The process was very easy, as promised. I have two problems, though.

First, the darn thing doesn't work. Whenever the paper transport mechanism
is operating the duplexer makes a loud Clack-Clack-Clack noise which does
not sound normal. When the paper should feed into the duplexer's "switchback
assembly," it just bumps into the back instead, resulting in a paper jam and
an accordion-folded sheet of paper.

I have my own theory about what is happening, but I would like to hear
informed opinions before I state it.

My second problem is that I can't figure out how to turn the thing off. Now
that I have configured the print driver to "duplexer installed," it tries to
use the duplexer every time I print something. I assumed that installing the
duplexer would cause another control to appear in the Print dialog box to
let me select whether to use it or not, or else the drop-down list of paper
sources would be expanded to include "Upper Cassette with Duplexer," etc. No
such luck. I can't find the control -- where is it?
 
First, the darn thing doesn't work. Whenever the paper transport mechanism
is operating the duplexer makes a loud Clack-Clack-Clack noise which does
not sound normal. When the paper should feed into the duplexer's "switchback
assembly," it just bumps into the back instead, resulting in a paper jam and
an accordion-folded sheet of paper.

I have my own theory about what is happening, but I would like to hear
informed opinions before I state it.
Click to expand...

I've not had a duplexer go wrong, but it sounds as if the paper
transport at the back of the duplexer isn't pulling the paper out of the
fuser. Not sure if that's a belt or a separate motor.. Another
possibility is that a sensor isn't detecting the paper and turning the
transport on. Third idea is that the printer is failing ton recognise
the duplexer.

Does it offer Duplex as an option unde the Print menu on the control
panel on the actual printer? If it doesn't, could be the duplexer isn't
seated properly on its serial connector underneath (the four pin plug).

I appreciate you can't yet get a test print, and even if it's a crumpled
one it'll be blank because the duplexer always prints the second side
first, so you won't see the test print until after the page has gone
through the duplexer and back through the print engine for the second
time.

If you can see Duplex as an option, turn it off because (depending on
operating system and printer driver) that may override any software
choice (see below).
My second problem is that I can't figure out how to turn the thing off. Now
that I have configured the print driver to "duplexer installed," it tries to
use the duplexer every time I print something. I assumed that installing the
duplexer would cause another control to appear in the Print dialog box to
let me select whether to use it or not, or else the drop-down list of paper
sources would be expanded to include "Upper Cassette with Duplexer," etc. No
such luck. I can't find the control -- where is it?
Click to expand...

You don't say which operating system; it varies. I can check on XP (if I
can get the machine out; I use it rarely), on Windows 3.1 (Yes!) and on
OS/2. On the latter two it's a set of three radio buttons to select long
edge binding, short edge binding (inverted page on reverse) or simplex.

I wouldn't expect it to be a paper source selection, though. More a
printing option.

(I take it you're in the USA, and not Jonathan Sachs the English chief
rabbi?)
 
I've not had a duplexer go wrong, but it sounds as if the paper
transport at the back of the duplexer isn't pulling the paper out of the
fuser. Not sure if that's a belt or a separate motor.
Click to expand...

According to the service manual (p.A-3) it's a motor: "As the paper exits
the fuser, the Switchback Solenoid (1) is activated. The Switchback Solenoid
moves the Switchback Input Paper Guide (2), routing the paper into the
Switchback mechanism. The Switchback Stepper Motor (3) then pulls the paper
out of the printer into the switchback assembly.
Does it offer Duplex as an option unde the Print menu on the control
panel on the actual printer? If it doesn't, could be the duplexer isn't
seated properly on its serial connector underneath (the four pin plug).
Click to expand...

No, no duplex option there at all. Your suggestion occurred to me, and I
checked the bottom of the printer to be sure that it was properly aligned
and fully seated on the duplexer. As far as I could tell, it was.

I had to remove the duplexer to make the printer work at all; removing power
from it and configuring the driver to ignore it did not help. I will put it
back on when I have a theory to test. The four-pin plug is a possibility,
but before I pursue it I will need to know how it's possible (if it's
possible) for the plug to fail to connect when the printer appears to be
correctly aligned and seated. (And how to fix it, of course, if that does
not become obvious when the problem is identified.)
You don't say which operating system; it varies. I can check on XP (if I
can get the machine out; I use it rarely), on Windows 3.1 (Yes!) and on
OS/2. On the latter two it's a set of three radio buttons to select long
edge binding, short edge binding (inverted page on reverse) or simplex.
Click to expand...

It's WinXP. Sorry I didn't state that.
(I take it you're in the USA, and not Jonathan Sachs the English chief
rabbi?)
Click to expand...

Oy veh. No, I'm not the chief rabbi of England (and I think he spells it
with a K, although I won't swear to it). I was astonished when I first heard
of him, though. One more of us, in addition to Jonathan Sachs the inventor
of Lotus 1-2-3 (who is a former college roommate of a friend) and Jonathan
Sachs who works for Microsoft, and another one who was a music student at
the college I attended at the same time I was there. I am not Jonathan
Sachs, as the joke goes, but another person with the same name.
 
Here's a random idea: after accidentally sending me a lower paper cassette
instead of a duplexer, could the seller have accidentally sent me the wrong
duplexer? For a LaserJet 4, for example, instead of a LaserJet 4 Plus?
 
Here's a random idea: after accidentally sending me a lower paper cassette
instead of a duplexer, could the seller have accidentally sent me the wrong
duplexer? For a LaserJet 4, for example, instead of a LaserJet 4 Plus?
Click to expand...

Don't think there *is* a duplexer for the LJ4.

In any case, the printer would complain. It certainly does if you fit
one of the earlier (LJ4 only) 500 sheet lower paper trays...
 
Jonathan Sachs said:
Here's a random idea: after accidentally sending me a lower paper cassette
instead of a duplexer, could the seller have accidentally sent me the wrong
duplexer? For a LaserJet 4, for example, instead of a LaserJet 4 Plus?
Click to expand...

See the parts catalog at TPW:
<http://www.printerworks.com/Catalogs/EX-Catalog/EX-AssblyContents.html#Duplex>
and
<http://www.printerworks.com/Catalogs/EX-Catalog/D10EXDuplexExtCovers.html>
"C3157A; Duplexer Upgrade; LJ 4+ / 4M+"
No listing for a duplexer for LJ4.
 
Does anyone have an idea what might be wrong? My gut feel is that the
duplexer is not truly broken, and I only need to change something in the
installation procedure or make some simple adjustment, but I don't know what
to look for.
 
Does anyone have an idea what might be wrong? My gut feel is that the
duplexer is not truly broken, and I only need to change something in the
installation procedure or make some simple adjustment, but I don't know what
to look for.
Click to expand...

Until the printer recognises the duplexer, forget about anything else.
That may not be anything mechanical, so check the wiring and the board
etc. in the duplexer, and for damage to the serial plug/socket (the 4
pin one).

I suspect that once it recognises it, the logic will turn on the
duplexer motor at the right time! If the printer doesn't know the
duplexer is there, it won't happen.
 
js: > the duplexer makes a loud Clack-Clack-Clack noise

Is the duplex power cord stub plugged into the
printer? The line cord plugs into the duplexer.
If the power cords are switched, the printer will
not recognize the duplexer (and it makes a
rythmic clicking sound).

If you can get the clack to go away, then take
the printer off-line, press
[Menu] once: "PRINTING MENU"
then
[Item] 8 times: "DUPLEX=OFF*"
(this sets the hardware duplex mode default)

And there was no duplexer for the original LJ4.
I bought an LJ4M+ precisely because of this.
 
Is the duplex power cord stub plugged into the
printer?
Yes.

If the power cords are switched, the printer will
not recognize the duplexer (and it makes a
rythmic clicking sound).
Click to expand...

It made that sound, although the power cords were correctly connected. (If
they were not, the duplexer would have been plugged into itself, and obvious
absurdity.) I gather that the printer did not recognize the presence of the
duplexer for some other reason.
If you can get the clack to go away, then take
the printer off-line, press [Menu] once...
Click to expand...

Whoa! That's a lot harder than maintaining two copies of the printer driver,
one configured for the duplexer and one not; but I considered that a kluge
which could not possibly have been the intended method of control.

Think about how using the printer's control panel would work in an office
environment, where the printer was meant to be used. Tom walks half-way
across the office to turn on duplex mode, and while he's walking back to his
office, Dick and Harry each print a hundred-page document that is NOT
supposed to be duplexed. Good? Not.

(Now, notice that Harry is Tom's boss.)

I discovered a new piece of evidence: with the printer mounted directly on
the 500-sheet cassette, I cannot make the cassette work. When I select
"Lower Tray" (an option which was in Print dialog box's "sources" list all
along), I get paper from the upper tray. When I select "Large Capacity"
(which was also there all along), I get paper from the manual-feed tray. The
printer does not seem to believe that the 500-sheet cassette is there,
either. That points to the printer as the problem. I looked at the
electrical connector on the printer, though, and I see nothing wrong. Can
you suggest anything further I might do without trying to play doctor on the
printer?
 
If you can get the clack to go away, then take
the printer off-line, press [Menu] once...
Click to expand...

Whoa! That's a lot harder than maintaining two copies of the printer driver,
one configured for the duplexer and one not; but I considered that a kluge
which could not possibly have been the intended method of control.

Think about how using the printer's control panel would work in an office
environment, where the printer was meant to be used. Tom walks half-way
across the office to turn on duplex mode, and while he's walking back to his
office, Dick and Harry each print a hundred-page document that is NOT
supposed to be duplexed. Good? Not.
Click to expand...

It's not suggested as a permanent measure. One normally operates by
having duplexing turned OFF at the control penel, then turning it ON
from software. But if it's on at the printer it might overrride the
software. Hence worth checking. But it's immaterial since that menu item
isn't appearing.
I discovered a new piece of evidence: with the printer mounted directly on
the 500-sheet cassette, I cannot make the cassette work. When I select
"Lower Tray" (an option which was in Print dialog box's "sources" list all
along), I get paper from the upper tray. When I select "Large Capacity"
(which was also there all along), I get paper from the manual-feed tray. The
printer does not seem to believe that the 500-sheet cassette is there,
either. That points to the printer as the problem. I looked at the
electrical connector on the printer, though, and I see nothing wrong. Can
you suggest anything further I might do without trying to play doctor on the
printer?
Click to expand...

Well, print a self test (select menu for tests, then self test, then
Enter). The self test sheet should indicate the presence of the LC tray.
If it doesn't, then it isn't seeing that tray either. As I noted before,
this isn't an option to check duplexer presence unless the duplexer
works! This is because you are never getting to print the reverse side,
which is in fact the 'first' side and the one the self test prints on.

If it isn't seeing the tray, look for damage to the plug/pins/whatever.
Either that or there is probably an internal fault (could be just a
broken wire to the plug).
 
Well, print a self test (select menu for tests, then self test, then
Enter). The self test sheet should indicate the presence of the LC tray.
If it doesn't, then it isn't seeing that tray either. As I noted before,
this isn't an option to check duplexer presence unless the duplexer
works! This is because you are never getting to print the reverse side,
which is in fact the 'first' side and the one the self test prints on.
Click to expand...

I tried that, and it says the LC tray is there. I'm not sure what
implications that has for my broken-connector theory, or why it isn't at
least trying to use the tray when I tell it to. (Or may it is trying to use
the tray, and taking paper from the printer's built-in tray is merely a
symptom of lack of success.)

Maybe if I can figure out how to make the LC tray work I will learn
something about how to make the duplexer work. The LC tray is easier to mess
with because at least installing it does not disable the printer.

I'm puzzled by the "paper source" menu, which lists:

Automatically Select
Auto Select
Upper Paper Tray
Manual Feed
Lower Paper Tray
Envelope Feed
Large Capacity

Never mind the mysterious distinction between the first two options, and
"Envelope Feed," which isn't installed; however the trays are named, the
list includes one more tray than the printer can possibly have! I'm curious
about what this means, and whether it's a clue to the problem.
 
I tried that, and it says the LC tray is there. I'm not sure what
implications that has for my broken-connector theory, or why it isn't at
least trying to use the tray when I tell it to. (Or may it is trying to use
the tray, and taking paper from the printer's built-in tray is merely a
symptom of lack of success.)
Click to expand...

This seems like a software problem, unlike the one with the duplexer.
Maybe if I can figure out how to make the LC tray work I will learn
something about how to make the duplexer work. The LC tray is easier to mess
with because at least installing it does not disable the printer.

I'm puzzled by the "paper source" menu, which lists:

Automatically Select
Auto Select
Upper Paper Tray
Manual Feed
Lower Paper Tray
Envelope Feed
Large Capacity

Never mind the mysterious distinction between the first two options, and
"Envelope Feed," which isn't installed; however the trays are named, the
list includes one more tray than the printer can possibly have! I'm curious
about what this means, and whether it's a clue to the problem.
Click to expand...

Looks like the wrong printer driver. You *have* got the LaserJet 4+
driver, not the 4P one?
 
This seems like a software problem, unlike the one with the duplexer.
Click to expand...

I'll accept that as a working theory, but I'm baffled about what to look
for. Ideas?
Looks like the wrong printer driver. You *have* got the LaserJet 4+
driver, not the 4P one?
Click to expand...

I'm using the driver for the "HP LaserJet 4M Plus," which is the specific
printer I have. It should be identical to the 4 Plus except for the
availability of PostScript. The 4 Plus driver is installed as well, and I
have used both, but I have not tried these tests with the 4 Plus driver.
 
I'll accept that as a working theory, but I'm baffled about what to look
for. Ideas?
Click to expand...

Not really; I don't use Windows...!
I'm using the driver for the "HP LaserJet 4M Plus," which is the specific
printer I have. It should be identical to the 4 Plus except for the
availability of PostScript. The 4 Plus driver is installed as well, and I
have used both, but I have not tried these tests with the 4 Plus driver.
Click to expand...

Yes, the 4M Plus is identical to the 4 Plus apart from a) PostScript
availability b) network connectivity, both of which are installable
options anyway.

I can't offer much more help on the Windows side....
 
Maybe if I can figure out how to make the LC tray work
I will learn something about how to make the duplexer work.
The LC tray is easier to mess with because at least
installing it does not disable the printer.
Click to expand...

Another possible trap awaiting is printer RAM. The
standard config for the LJ 4+ was 6MB, and at least
10 MB is required for duplex printing. Unless you
have at least 10, you may not be able to enable the
duplexer in driver setup menus.

This is apparently due to the out-of-order rendering
of the pages, requiring buffer for 4 pages (2 sheets).
 
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