BH-C-360, C3721, Fuser abnormally high temperature, interesting find.

[Hansoon]

Customer called me that several sheets of paper where wrapped around the lower fuser roller. Removed them and cleaned the fuser roller/film with silicon oil as I always do in such cases with B&W machines.

However, during firing up of the machine it coded out with C3721 for too high temp in the center of the heating roller. Played a little with other fuser units in this machine and it turned out, as expected, that the problem lays in the fuser unit itself. Since none of the thermistors nor wiring was damaged it had to be another reason and it turned out after some testing that the use of excessive silicon oil prevented the film/roller from turning and therefore letting the middle thermistor believe that the fuser was overheating. After removing the excessive oil the service code went away and everything turned to normal again.

Just wanted to share this with you guys in case you didn't knew already.

Hans

[blackcat4866]

Re: BH-C-360, C3721, Fuser abnormally high temperature, interesting find.

I saw this for the first time on the Mita DC-1656. Some of our techs were greasing up the plastic pressure roller bushings on rebuilding the fuser. The pressure roller isn't driven, just by contact with the heat roller, so when the grease began to thicken up the pressure roller would slow, and we'd get jams in the fuser.

If the bushings were left dry the roller spun fine. This was before the days of creaky color fusers, which aren't really bushings they're heat collars and don't have to rotate, just insulate the bearings from heat.

I also saw this on a Kyocera Alphard. It's an old tech trick to drip a few drops of fuser oil on the fuser rollers, then heat up the fuser a few times. It loosens up any buildup. Again, since the pressure roller is driven by the heat belt only, the reduced friction allows the pressure roller to slip, jam, and give fuser drive errors. A member here suggested adding a few drops at the rear only, running a dozen blank pages, then a few drops at the front, and running another dozen blank pages. Works fine.

Thanks for sharing. =^..^=

[Hansoon]

Re: BH-C-360, C3721, Fuser abnormally high temperature, interesting find.

Cat I experienced also in the past that phenomena that rollers are slipping because of the oil used for cleaning but that it codes out with overheating of the thermistors due to not enough moving of the rollers was new to me.

Hans