Disconnect the power to boot, a preheating operation, the machine back to the standby state. The printer and computer is disconnected from the data line, directly print a test page, the machine does not have reaction. As the machine preheating normal, normal fixing component description. With the exchange will be the network interface board exchange test, no action. The motherboard and exchange, the toner cartridge exchange, still did not solve the problem. Imagine the exchange parts are exchanged, or not, the machine all apart, found a contact and the contact point deformation cartridge. This contact is used for toner grounding, front door contact switch cartridges, due to the deformation and no detectable drum. The contact is re installed, the normal operation of the machine.4PHservice manual download site