Sharp MXB401 Almost Blank Copies

**MFPs R Now PCs** · 08-17-2015

We have a Sharp MXB401 in the field that we replaced the Developer Unit, Drum Unit and Fusing Unit in 3 months ago and everything has been fine until Friday. It is producing almost completely {BLANK - edited,oops} copies/prints (including the self test/list, simulation 22-06-01). Only a very faint image appears on one edge. I swapped the Fusing Unit, Developer Unit and Secondary Transfer Roller in the right door with NO CHANGE. I inspected the the Primary Transfer Belt and the Drum unit and everything appears to be fine except for some clicking {I CAN FEEL WHEN TURNING DRUM BY HAND - edited} in the drum unit, however it will turn past it in both directions. Also checked the High/Low Voltages with simulation 08-.... and ran the LSU Test, all passed. ANY IDEAS? Help, Thanks in advance!

**blackcat4866** · 08-17-2015

My bet is that clicking you're hearing is the primary charge, discharging to the drum. That also explains the black copies. =^..^=

**MFPs R Now PCs** · 08-18-2015

Originally Posted by blackcat4866

My bet is that clicking you're hearing is the primary charge, discharging to the drum. That also explains the black copies. =^..^=

Ooops,

Did I say Black Copies, they are Almost Completely Blank, and the clicking is what I feel when turning the drum...?

**blackcat4866** · 08-18-2015

Well that changes things a lot.

What happens if you remove the primary charge? It should go completely black. If it doesn't you've ruled out charge as the issue.

I'm wondering if you might be losing drive to the developing unit? =^..^=

**drowranger** · 08-18-2015

this seems to be an arcing mc grid. run a sim 25-1 and check the value. better change or swap the drum unit and see what happens.

**spanky** · 08-18-2015

Stop the machine during the copy cycle to see if the image is right on the drum or the transfer belt.

If image is right on the drum and not the transfer belt you have a problem with in the primary transfer with the roller that brings the belt down to the drum.

If the image is bad on the drum you could have a problem with the shudder on the LSU not opening properly.

**mojorolla** · 08-19-2015

These units are notorious for the IT belt cam collars shattering on one side. These parts are all plastic and come with the frame, no repair possible. You will need the entire belt unit.

**mojorolla** · 08-19-2015

odd, editing is not working..... Turn the cam by hand and look at the 1st transfer roller inside the belt unit, it will drop down towards the drum. If only one side of the roll drops down, the cam is shattered.