blank in black

[johnnyquest]

has anyone seen an mp c401 give good prints (and copies), but completely blank in black? no residual anywhere. strangest thing is it doesnt code. i can force process control no problem. i have replaced the k pcdu, itb, ptr, hvt, laser, all pcu, and firmware.

[M94]

I'm not quite sure I understand what you're asking, like anything set to monochrome is blank? Or even on mixed docs anything using K doesn't show up?

Edit> If you can't get black (K) to show up anywhere at anytime then my first thought is that it's not charging properly to attract toner, have you stopped it mid print to see if toner makes it to that point?

[BillyCarpenter]

has anyone seen an mp c401 give good prints (and copies), but completely blank in black? no residual anywhere. strangest thing is it doesnt code. i can force process control no problem. i have replaced the k pcdu, itb, ptr, hvt, laser, all pcu, and firmware.

Not a lot of info. What kind of prints do you get in color mode?

[johnnyquest]

in color, you get all colors except black. there is no residual image on the tbelt, or drum. in k you get blank. k pcdu was replaced

[BillyCarpenter]

in color, you get all colors except black. there is no residual image on the tbelt, or drum. in k you get blank. k pcdu was replaced

I would think either loss main charge @ black or loss of drive to black DV unit.

[M94]

in color, you get all colors except black. there is no residual image on the tbelt, or drum. in k you get blank. k pcdu was replaced

Maybe a more experienced tech can correct me but that kind of has to mean that the black roller isn't charging properly right? Or the developer unit isn't functioning properly. If the rest of the printer is functional your issue really has to be within 6 inches of that area... Unless it's an oddly specific fault on one of the circuit boards involved, maybe even as simple as a detached or broken cable between the two?

[BillyCarpenter]

Maybe a more experienced tech can correct me but that kind of has to mean that the black roller isn't charging properly right? Or the developer unit isn't functioning properly. If the rest of the printer is functional your issue really has to be within 6 inches of that area... Unless it's an oddly specific fault on one of the circuit boards involved, maybe even as simple as a detached or broken cable between the two?

One way of seeing if black DV is turning is to wipe off all the toner/developer on the mag roller, make a copy and pull the DV out again and see if the mag. roller turned.

[fshead]

do a sky shot and stop it as it hits fuser unit.
PULL drums,ITB unit and see if there is any black on the k drum or ITB unit.............
there are contacts that get dirty in the front that touch the drums/dev units when pushed in..
bad contact,no charge on charge roller...i know its hard to do and close the drum cover but make sure that lock lever
above K drum is not mucked up...

[slimslob]

Normally a problem with the drum charge will throw a Service Code, SC. Since it is only K and the color transfer rollers are lifted separate from the K transfer roller, I would say check the ITB assembly to see if the K transfer roller is binding and not pressing the belt against the K drum.

[RMC8112]

I ran into a similar issue with a MP C5503 and found that one of the gears was chewed up. I would remove the black PCDU and check the gears.