We have been getting multiple Konica Minolta bizhub C451 and C550 machines in that have this constant squeaking sound. This series always turning something/running at all times that its predecessor did not and it seems to be related to that. We are currently chasing this noise at several customer sites and are not having great luck getting the exact location nailed down. HELP?!
Also on KM's site they have a new tech pub that is audible and can listen to all the different noises and where they originate. Still can be a pain in the ass to nail some of them down, hope the new series of machines have a different system.
Main problems are fuser and the ADU drive. The gears that are above/to the right of the fuser, a blue bushing in the ADU entrance (all gears/axels there, really), the gears on the right hand side of the fuser unit and the fuser drive gears behind the covers around the main drive area seem to squeak.
Buy some DrySurf and heat resistant grease and you're set. Also, silicone lube works wonders for the gears and shafts around the ADU area.
You can also activate the switches that the right hand door activates to run it open, to see if you can better locate the sound. Since there are alot of different sources for it, it's hard to pinpoint exactly.
Once lubrication and rectification of the squeaks is done, ensure low power mode is set to an absolute maximum of 30 minutes, Any more and your asking for trouble. Machines rarely used in a walkup copy environment i set to 15 minutes.
Sleep mode can be what ever you like of a greater value or off, it doesn't matter. Low power mode will stop the fusing unit / drive rotating and the machine awakes from this mode in under 10 seconds anyway.
I've never had to go back to this series machine twice for squeaks, I also use HP-500 grease.
I just had one squeaking like mad really loud, it was coming from the transfer belt cleaning gears. really hard to locate because it sounded like it was coming from the rear of the machine. some canned air and a dry teflon lube and the squak has been gone for months.