HP M402n Jam In Cartridge Area. Open Open front door and clear jam.

[Franco_C]

I work in the IT Dept of my company and we use a LOT of the M402n printers.  Lately we have had a lot of them give the error Supply Memory Error".  We tried resetting back to factory default, swapping toners, but nothing fixes the error.  So after doing some googling, I thought I would attempt to swap some boards to see if I could fix the error.

So I took apart the printer and replaced the 2 boards on the left side of the printer:

imgur.com/a/jGbsq2m (Pics of my printer boards)

These are HP Part #'s: RM2-7509 & C5F95-60001

Once replaced, I am no longer getting the Supply Memory error, but now I am getting a "Jam in Cartridge Error".  I have tried multiple of both boards and I have even tried this on multiple M402n printers (That initially had the Supply Memory Error" and now all of them have the Jam in Cartridge Error.  The printer is as shown in the pictures above and I am pressing the metal tab on the left after powering on to simulate the front door being closed.  Any ideas or suggestions what I am doing wrong?

[Valsimot]

The RM2-7509 controls sensors that detect paper jams, I would double-check the wiring on that board, if you are lucky you might have just minor wire connection problem.

[Franco_C]

Thanks for the suggestion.  I took another picture of the RM2-7509 board  - See: imgur.com/a/CD9ltKv

I have checked all of the connections, nothing seems obvious.  I wish I knew which of those connectors would be causing this issue.  So frustrating.  The multi-colored wires on the bottom and right of the board all look pretty solid and none of the wires are broken.  What is strange is that I have tried fixing 3 different M402n printers and they ALL had different issues (including one that worked, but the fuser had a line on it, so I replaced the fuser film).  Once I put it back together, I got the same Jam in Cartridge Area...