An Unknown error

Yesterday I got asked help with a Bizhub C754e that had some scanner problems. Most mornings the machine would have a C-9401 error when first used. According to the manual C-9401:

While this seems to indicate that the exposure lamp is the fault I was asked to change the CCD first. We didn't have a new CCD in stock but we did have a Bizhub C654e that was being stripped for parts that I could take the CCD out of. 

I went out to the C754e first thing in the morning to find the scanner had been locked out and the history showed that the C-9401 error had caused this. The actual swapping of the CCD was straight forward as was getting it lined up.

However when I powered up the mc I was given a C-D291 error. When I looked up the code in the manual I found an entry for the code but the only description there was "Unknown". What does that mean?

I knew that it was most likely caused by the CCD so I checked that all the cables were seated correctly but that was ok. The only thing that I could think that was different between this CCD and the original was the firmware. The manual never mentioned updating the firmware when installing the new CCD but the manual also doesn't mention anything about using a 2nd hand CCD either. 

The machine already had the latest firmware loaded on it as did the machine I took the CCD out of but I loaded up this firmware again, rebooted the machine and now it works.

So if you have a C-D291 error or other unknown error try reloading the firmware, you might get lucky. Also changing the CCD fixes the C-9401 error.