Weirdest Bizhub C452 print issue I've seen in my 20 years

[Dougtech]

Hey all,

Got a bizhub C452 with about 400,000 prints total. Can only see this issue when printing on 11 x 17 paper. Tried scanning but the light gray part of the issue doesn't show up, so here's my best description

I created an 11 x 17 text document with lines of text - about 3-4 lines of different colors text -black, blue, red, orange, light blue and green. When I print it out I get this problem - the black, red, light blue, and orange all print fine. The trailing 4" of the blue and green you can see the black "showing as a light gray on print" starts slowing separating out so that by the end it is mis-registered by about 2mm. This happens during only the trailing 3-4" and only in green and blue.
I've tried the firmware, main PCB, laser unit, laser unit drive board, all imaging unit, black drum, developer unit, transfer belt, and transfer belt drive unit.
I'm about to change the print board, but just thought I'd throw this up here to see if anyone has ever had this issue????

Added - print board no fix, same issue is seen on the color registration printout - C, M, and Y all separate out more and more on the last 6 sets of registration marks

Thanks for any help

[Zesti]

I hope you have done skew adjustment and color registration settings before replacing boards. Do consider replacing the fusing unit.

[B0265]

Try replacing the fusing loop sensor.

[Dougtech]

I hope you have done skew adjustment and color registration settings before replacing boards. Do consider replacing the fusing unit.

Hi
Yes did the color registration, skew, and LD adjustments before and after the boards.

[Albonline]

Hi
Yes did the color registration, skew, and LD adjustments before and after the boards.

try a new fuser unit.

[EarthKmTech]

As already said, the fusing loop sensor will cause this - if the actuator under the fuser has been snapped off by careless paperjam removal (is there any other way?) the fusing motor will run at full speed and end up tugging on long paper and causing the belt to turn too fast, totally screwing up color registration on the final 3/4 of the long sheets.

This actuator is 30 cents and takes 5 minutes to change. every big office engine from c350 to c754 does the same thing.

[JR2ALTA]

a 30 cent actuator after

main PCB, laser unit, laser unit drive board, all imaging unit, black drum, developer unit, transfer belt, printer board and transfer belt drive unit.

gotta love this job

[D_L_P]

If I'm reading your post correctly, the image is what is going crooked not the paper. Is that right? When the color lines separate, is it intrack or cosstrack?

[Dougtech]

Try replacing the fusing loop sensor.

I will try this next, already tried a fuser unit. Will let you know - adjusting the TRAILING EDGE REGISTRATION adjustment in service mode does bring it closer but not into full registration.