Weird issue on Bizhub 751

[Cookr]

Had a call end of the day Friday for jamming from tray 2 on a BH 751 so I figured I would swing in and give it a quick check jamming was just worn feed tires but I noticed that it said there was no paper in tray 1 but the was weird thing is if i leave tray 2 open and make copies even though it says no paper it will still feed from tray 1 and when it runs out it says that there is a jam. Haven't done much it yet as it was the end of the day but I did switch out feed units and it still read no paper. Any thoughts?

Thanks

[Synthohol]

have had the same in the past and it was #9 broken.
but check if 18(s) are seated right.9or18.jpg

[Iowatech]

I have only worked on analog Konicas, so take this with a grain of salt please.
Still, if the machine can't detect when drawer 1 is out of paper, I'd be focusing on the sensor that detects that condition.
I don't know if that is part of the feed unit, sorry. But if it is you might check that the paper lift plate is in good shape, as usually the feeler for that sensor falls through an opening on the plate when the tray is empty.
Also, you might double check the connections for the feed unit you installed. On the machines I currently work on, I have found that there is a surprisingly small difference between a fully seated connector and one that is not, and that tends to be more apparent when I'm in a hurry.
And now, I cede the floor to people who have far more experience with this machine, and apologize if this was a waste of time.

[Synthohol]

and apologize if this was a waste of time.

not at all, thats what part #9 i pointed out does.

Cookr, i just reread your post and you said you swapped feed units but you didn't specify if the issue followed the unit or stayed in tray 1.
i didn't want to assume.

what does it read under state conformation - sensor check - 11-1? and 16-1? H paper present, L no paper.

[Cookr]

not at all, thats what part #9 i pointed out does.

Cookr, i just reread your post and you said you swapped feed units but you didn't specify if the issue followed the unit or stayed in tray 1.
i didn't want to assume.

what does it read under state conformation - sensor check - 11-1? and 16-1? H paper present, L no paper.

When I swapped units the problem stayed in tray 1. I am going back there today to spend some more time on it as I didnt have much time Friday so hopefully just something stupid i didnt notice

[allan]

Check for bent pins on that connector.

[Cookr]

Alright I've changed trays 1 & 2, swapped feed units from tray 2 to 1 and from 3 to 1 both times problem of reading no Paper stayed with tray 1. Here's what happens also I put 2 sheets in tray 1 then ran 5 copies on auto tray it took the two from tray 1 then switched to tray 2 for the rest and vise versa

Also in sensor check 11-1 reads H with paper and L without but 16-1 reads H either way

[Synthohol]

Ok. 16-1 was for paper limit (paper has lifted the takeup assy and stops lifting the tray.
I would reseat all the connectors on the prcb but first look behind the trays and in the elec sockets that electrically connect the tray to the copier.
Chech the pins on both the yray and inside the machine. Ive seen a small paper fragment stuck in there from a failed jam removal..
You may even swap the whole tray to see if its the machine or the tray causing the false signal..

[Cookr]

OK. I was back there this morning and re seated all the connectors on the PRCB no luck. Replaced the PRCB got C-C111 updated the firmware and got the machine to boot up still no paper detected in tray 1 checked all connectors in side the machine and on back of tray all look fine also changed the trays still no luck. I am lost on this one any more ideas? Thanks

Still don't understand why the machine will feed from tray one even though its says it has no paper.

[mo0651]

I would look in the puck in the back of machine where the drawer connectors slide into when closed. a small piece of paper in those can cause all kinds of trouble!