Fixing Kyocera fs-6021dn errors 7401 7402 7403 and 7404
At the office, we had a cheap Kyocera fs-6021dn. After a few years of use, the printer finally gave up with error 7403. Looking at the service manual, the error description is:
Developing unit M noninstalling error
No density detection signal is output from toner sensor M in developing unit M.
Possible causes:
– Defective connector cable or poor contact in the connector.
– Defective toner sensor M.
– Defective engine PWB.
So I found a video showing the disassembly of the printer in order to find the drum developer transfer units. This video showed the removal of the toners and the transfer belt in order to find the drums. When I removed toner and transfer belt (which also wasn’t completely sane, but it seems that the defect found here didn’t really cause real problems for the printer), I found out that the contact of one of the drum units was loose. I just pushed it down so that the connector had contact again and tadaa – no more error 7403
System programmer