AlanS

asked Apr 10, 2008 at 11:01am
Hp HP LaserJet 5MP

LJ5MP can't pickup from tray

Quite suddenly my HP 5MP will not pick up paper from the normal lower paper tray. One day working reliably, the next failed.

It will feed and print from the front multi-purpose tray.

I tried cleaning the pickup roller, and cleaning dust in general.

After looking at other posts, I also checked the oblique rollers, but they were clean and I found no scraps of paper.

If I try to print, after a few seconds of normal noise, the orange paper jam light comes on. However, no paper has even moved.

If I peer through the gap at the back, the pickup roller does not move down -- is it supposed to normally?

It doesn't seem to be related, but while checking it over I found one of the catches on the rear door had snapped off. But as paper still feeds past it from the MP tray, I doubt it is the problem.

I have seen the plastic pickup roller shaft break. If the roller isn't turning, that's what I would suspect. Take the tray out and lift up on the black plastic flag dangling next to the pickup roller. Then send a print job to it (you can just hit the button on the top). You'll be able to see what is happening a lot better. You can try grabbing the roller and see if you can feel it trying to turn.
by moe on Apr 10, 2008 at 12:48pm Add comment
Thanks Moe.

The pickup roller doesn't move at all.
The front door/MP tray does move up a bit while it's trying to print -- is that just an fallback after the normal pickup failed or could it be somehow stuck in just using MP tray?

How do I get to the pickup roller to check if the shaft is broken? How much does this part cost, approx?

- AlanS
OK, I think we're focusing on the wrong thing. It looks like the MF is trying to pickup even though there isn't any paper in the tray. That would by why the lower roller never turns. Did you by any chance take the top off? The paper sensor flag hangs down from the top and has been known to fall off.
by moe on Apr 10, 2008 at 8:13pm Add comment
An easy way to test if you do not see the black plastic flag is that in the center of the bar that lifts up will be a small cutout. Stick a popsicle stick or flat blade screwdriver in that slot if nothing is there now while you press the button for a self test and see if the paper not picks up from the paper tray. If it does you have lost the little flag that hangs from the top cover.
by dmzcompute on Apr 10, 2008 at 8:42pm Add comment
Sorry I was away from my PC for a few days.
Unfortunately the printer didn't repair itself, so....

Thanks for your responses.

> moe (4/10/08 8:13 PM)

Well, I had the printer upside down for a while, but that was after it failed to print.

I'm afraid I can't work out what you're referring to:
"The paper sensor flag hangs down from the top"
-- The top of what?


> dmzcompute (4/10/08 8:42 PM)
" the black plastic flag is that in the center of the bar that lifts up"

-- Sorry, still lost. What "bar"?


I have the HP manuals:
the "HP LaserJet 5P/5MP, 6P/6MP Printer Service Supplement"
I guess you have these to hand.
It has a part list and diagrams with HP ref numbers.
Can you advise what parts, by HP's name or number, you're referring to?
by AlanS on Apr 16, 2008 at 1:13am Add comment
RB1-5939-000CN.
by dmzcompute on Apr 16, 2008 at 5:18am Add comment
Okay, I do see RB1-5939-000CN, ("Arm, Tray 1 sensor"). It seems to be okay, moves freely.



by AlanS on Apr 16, 2008 at 6:39am Add comment
The question is when you try to print from the bottom tray does the roller in the manual feeder turn. If it does then that sensor may not be all the way down where it blocks the light of the sensor it intersects. In other words if the sensor light is received by the other end it thinks tray 1 has paper and attempts to draw from tray 1. That is why I told you to put a screwdriver tip down in the slot that flag rests so as to block the light and see if it works. Just because the flag moves freely does not mean it is far enough down to block the sensor light.
by dmzcompute on Apr 16, 2008 at 4:29pm Add comment
When I try to print with the lower tray loaded and nothing on the MP tray, the roller on the MP tray turns; the paper guide plate lifts up two times (trying to feed paper in) the pickup roller on the lower tray does not move.

Should the paper guide plate be moving when there is no paper on the tray?

Does that mean the problem is the sensor on the MP tray?

I'm a bit handicapped because I never looked closely at this when it was working correctly, so I don't know what "normal" operation is.






by AlanS on Apr 17, 2008 at 12:57am Add comment
PROGRESS!

dmzcompute's suggestion as to the cause seems correct, though I could not affect the sensor with a screwdriver or stick.

However, when I changed the Windows printer properties paper source from "Automatically Select", is it has been for the last couple of years, to "Tray 2 (Paper Cassette)", it prints!

Changing it back to "Automatically" and it tries, and fails, to print from the MP tray.

This seems consistent with the printer detecting paper in the MP tray when it is in fact empty.

I'm still foggy on exactly where the paper sensor in question is, how it works and if this is fixable.
by AlanS on Apr 23, 2008 at 3:05am Add comment
Lets try and explain it this way. The sensor is the item the black flag the part in question above swings thru. Best way I can describe it is if you are in a tunnel and at some point there is a light beam going accross the road and when your card goes thru the beam you block it. Well in the printer's case the beam has to be blocked all the time except when paper is in the tray. That black arm rests in the center of the sensor which is like the tunnel without a top and blocks any light from going accross. My screwdriver test is putting the screwdriver bit in the actual sensor opening to stop the light just in case the black flag that hangs down is not doing it. Your issue has to be the black flag and nothing else since the sensor is working for if it were not then the roller would not turn. Light is going accross and is being received. The flag is not doing the job and is somehow in the wrong position where it does not block the beam of light.
by dmzcompute on Apr 23, 2008 at 5:05am Add comment
I understand the theory -- it's just the practical problem of locating the components in question.

So if you can be patient with me: exactly where is the beam and the sensor? Are they accessible? Which part of the arm is supposed to block this?

Is there perhaps a diagram you can refer me to?

I did try poking a screwdriver in the slot below the arm, but with no obvious effect. The printer still apparently detected paper in the MP tray and tried to print to it.
by AlanS on Apr 23, 2008 at 6:56am Add comment
The sensor is an optical one. It has an LED on one side and a photocell in the other. The arm that hangs down blocks it until a piece of paper lifts it out of the path of the beam. If nothing is blocking the light, then the printer thinks there is paper present. Since the light is shining across, then you are probably not blocking the right thing. Forget the screwdriver. You can see the sensor, it is a black U shaped part that is directly below where the arm hangs down. Wad up a piece of paper and stick it down the opening.
by moe on Apr 23, 2008 at 8:30am Add comment
> You can see the sensor, it is a black U shaped part that is directly below where the arm hangs down. Wad up a piece of paper and stick it down the opening.

I can see the arm. I canot see a "black U shaped part".
What opening do you mean?

Is it in this diagram?:
http://www.printerworks.com

If so, what part number?

I guess "Photosensor PS5"?

But how do I get to it? Do I need to remove a panel?

I realise I may sound like an idiot to you, not seeing something apparently in front of me. - AlanS
I'm done. There are some people who just can't be helped and that is why printer repair shops exist. Maybe someone else has the patience to help someone who doesn't want to be helped.

BTW, I grabbed someone out of the office who doesn't work on printers. Showed him the post, stuck a 5P in front of him and asked him if he understood it and he had absolutely no problem following my instructions.
by moe on Apr 23, 2008 at 10:51am Add comment
Sorry. I submit however that being in the same room is a bit different than typing words.

I've spent hours explaining things about computers (and printers, for that matter) over the phone to less experienced people, so I know how frustrating this can be.

I got a quote last week. It would take me three hours travel by public transport to drag the printer to a repair shop and cost more than the printer replacement cost for the inspection charge. So if I can't fix it myself, it doesn't get fixed.

If you're still reading, this is what I see:

http://i281.photobucket.com/albums/kk223/AlanHK/DSCN0830.jpg

The arm is obvious enough, in the centre.
The only part that is "directly below" it is the shiny steel Paper Guide Plate. I do not see a "black U shaped part". I see a black rectangle to the right with two vertical slots. Is that what you mean?

If you don't want to spend any more time on this, fine, you have no obligation, but please don't insult me.
by AlanS on Apr 23, 2008 at 6:32pm Add comment
You are looking at the right part. The black thing hanging down is the FLAG. Below the flag is the U shaped sensor and the bottom the the flag is supposed to be in the middle of the U shaped sensor almost touching the bottom of it. My feeling is the flag is not low enough so it does not block the light. Are you sure you have the top cover all the way down because if you are even an 1/8th of an inch to high the FLAG will not block the led in the U shaped sensor the FLAG is sitting over.
by dmzcompute on Apr 23, 2008 at 7:10pm Add comment
Really, how difficult is it to wad up a piece of paper like Moe suggested and stick it down in the opening the flag goes down into? To further clarify the opening, that would be the rectangular cut in the metal plate. It's the only thing that even looks like an opening. That would most surely block the light from reaching the photocell and end this all to lenghty discussion that should have been resolved 2 weeks ago. To make it really clear what happens when you do that, the printer will definitely not see the MF tray anymore and be forced to pickup from the lower cassette tray.
by Anonymous on Apr 23, 2008 at 7:49pm Add comment
Anonymous:
> Really, how difficult is it to wad up a piece of paper like Moe suggested and stick it down in the opening the flag goes down into?

Not difficult at all. I did that two weeks ago, as I mentioned in my post of 16th April. It didn't work. I tried it just now. The printer still tries to feed from the MP tray.

dmzcompute:
>are you sure you have the top cover all the way down

I pushed the cover down while sending a test print and also while trying to block the slot below the flag. Still tried to feed from the MP tray.

Am I supposed to be able to see the "U-shaped sensor"? Because I still can't. Is it visible in my photo?



by AlanS on Apr 23, 2008 at 8:18pm Add comment
It is below the metal plate. The only way sticking a wad of paper down there and it still not working is if somehow and I have never seen it, the sensor itself has some how moved and is no longer being blocked by the flag. If you remove the top cover of the printer which is not easy the flag stays with the cover and then you get a better look at the hole in the plate and can clearly see the sensor below it. I do not know what else to tell you since the only way that manual feeder roller turns is if that sensor does not have its beam blocked.
by dmzcompute on Apr 23, 2008 at 8:53pm Add comment