bizhub C650 keeps asking for TN-K even though the toner is full

[AjitN]

What about toner supply motor. If faulty, it will not add toner in toner hopper. Add some toner manually in hopper just to isolate the problem area. If machine detects toner after manual addition, you need to check toner motor & backward all parts,
Hope this helps.

[methogod]

If you eliminated the IU and the toner --- its got the be the hopper...
We had the same thing happen to the YELLOW toner hopper...

I would vacuum it out well its deep and holds a lot of toner, even though its small... See if the sensor comes back after a complete reboot.
If it still reads as empty, i would then do the follow...

if you have a parts machine you can rebuild it, or if you have a know all parts are good, i would swap the entire assembly, at least to test.
After taking it apart, we couldn't find anything wrong - no motor issue, gear issue, so must of been the sensor. So we swapped all 4 hoppers.

We ruined 2 IU before figuring it out.

Also you can eliminate the toner hopper auger motor unless its both the black and the magenta. The toner auger motors are 2 motors that drive 2 clusters of gears (Y/C and M/K), so when 1 fails they both fail.

[Oneir]

If you eliminated the IU and the toner --- its got the be the hopper...
We had the same thing happen to the YELLOW toner hopper...

I would vacuum it out well its deep and holds a lot of toner, even though its small... See if the sensor comes back after a complete reboot.
If it still reads as empty, i would then do the follow...

if you have a parts machine you can rebuild it, or if you have a know all parts are good, i would swap the entire assembly, at least to test.
After taking it apart, we couldn't find anything wrong - no motor issue, gear issue, so must of been the sensor. So we swapped all 4 hoppers.

We ruined 2 IU before figuring it out.

Also you can eliminate the toner hopper auger motor unless its both the black and the magenta. The toner auger motors are 2 motors that drive 2 clusters of gears (Y/C and M/K), so when 1 fails they both fail.

Will try this and let u know.

[pappyvonsillypants]

I have been a tech for 12 years. only on here for a tid bit. when you pull the toner bottle out there is a chip at the bottom in which the machine reads. the "reader" if you will, is a few metal contacts. they are easily shorted if not perfectly formed. take the front cover off and you will be able to see the sensors up close from the rear and see if any are not seated right, or possibly bent. the nvram, drums and ius can be new and replaced all day, but if the read switch is bent or deformed you will have issue after issue. hope this helps and if it is not easy to follow let me know ill try to be more specific.

[Synaux]

bizhub C650 keeps asking for TN-K even though the toner is full, changed the IU-K and the same thing, tried another toner and no change.
I changed the engine board and the problem persisted. I changed the NVRAM and the problem still continued. What could be the problem????
My business is losing $$ daily.

Is the machine working at all? If I understand correctly, I have this same exact issue and the machine was operable for about a year like this. After some time of this erroneous error, someone took out the black IU and that is when we noticed that the toner-flap was not seating correctly.
The fix: Rubber bands!
I will try to take a pict and post it later today