why doesn't my hp laser jet 4050tn recognize tray 2 anymore?

[jrhender]

My printer is no longer recognizing tray 2 anymore.  I swapped 2 and 3, but I still get "tray 2 open" and less often a message to load paper into tray 1.

I don't see anything in there that might be blocking it from fully closing, but it won't print from tray 3 while it shows 2 is open, either.

[Repairatrooper]

Can you clarify trays because sometimes HP number conventions confuse people.

Tray 1 is the drop down manual tray

Tray 2 is the first paper drawer

Tray 3 is the last drawer.

From your description and model number it sounds like you have the printer with 2x250 sheet trays built into the printer. There is a board that contains microswitches that detect paper tray insertion and paper size. Over time these switches wear out and you need to either replace the switches or the board.

[jrhender]

Your analysis of tray setup is correct.

How much do the replacement switches and/or board cost, and how easy is it to replace them?

[AlS77]

I agree, it sounds like the Feeder Control Board (RG5-2685-000cn) is not recognizing the tray being installed. I used to replace the board for issues like that all the time too, but then I found that if I bend the metal leaf springs that the tray pushes on to activate the switches to produce a little more force on the switches, it resolves the issue just as well if not better as I think the springs just lose their pressure a little as they age, usually causing a reading of a different paper size, not that the tray is not even loaded. This sounds more like a bad switch issue, but try the spring tension first. It's best to remove the springs from the printer to adjust them so they don't get stuck on the sides of the switches. It's not terribly difficult to remove the board and springs, but does require quite a bit of disassembly. The service manual will help. You need to separate the print module from the feeder module and remove the covers from the feeder module.

Note: I found that even the replacement Feeder Control Boards I would get often have switches that were just as flaky as the one I was replacing, hence why I began adjusting the spring tensions.

Here's a link I found to a service manual online:

https://rtellason.com/manuals/LJ4000.pdf

[Repairatrooper]

back when we actually fixed these we were buying replacement contact switches from Digi-key and soldering them in place. In testing the switches we found that the action on  them was worn out. If you remove the board you can press the switches and if they do not make a noticeable click then chances are they are bad.