Mpc4500 sc491

[mrfuser]

Does anyone know which PCU it refers to on this code or is it just something you have to check them all?

[slimslob]

If it occurs during B/W copying and printing, start with the black.

[ruben]

From Goose's Guide:

B222/B224	SC 491	Drum/dev bias error - replace drum unit(s)
B222/B224	SC 491	Drum/dev bias error - replace high voltage supply unit
B222/B224	SC 491	Drum/dev bias error - replace paper transefer unit
B222/B224	SC 491	Drum/dev bias error - replace paper transfer unit

From Ricoh Tech Tier 2 (ignore the references to the cyan drum, check all drums instead):
[Symptom]
SC491 cannot be reset.
When the SC does not occur, color banding occurs at the cyan drum pitch when color copying.


[Cause]
A pin hole has occurred in the cyan OPC drum.
When the drum unit was pulled out and checked, a large amount of toner was stuck to only the top of the color OPC drums. If there is only black, the black OPC drum is faulty.
[Resolution]
Replace the cyan optical drum.

It occurs on the OPC drum for each color so you must investigate to determine which OPC drum is faulty.

[mrfuser]

Looks like all colors are coated and not cleaning. Anyone think power supply bad? Swapped cyan and did nothing.

[slimslob]

Since process is write to no charge, it sounds like no charge voltage.

[mrfuser]

OK strange thing is I tore apart the cyan unit and put it back in was getting ready to give up and the machine reset itself and started working

So I’m guessing there must’ve been something going on there