Removing HP M607 M608 M609 Laser Printer circuit boards or Smart Boards even with the printer off and unplugged can damage components and smart boards.
Warning: There are no user-serviceable parts inside the laser printer circuit board areas. Only qualified personnel should disassemble the printers printed circuit boards, and this procedure must be done with proper electrostatic discharge (ESD) protection.
Why Laser printers have capacitors and other components (they're like small, quickly discharging batteries) inside them. When power is removed, these capacitors may still provide enough electricity for a short time to keep the device from completely resetting. Their memory can stay active for a few seconds because it is being powered by the capacitor.
The reason that capacitors are used, is usually so that a device can have very carefully regulated electricity in direct current (non alternating, so it doesn't go up and down, but just holds a steady voltage like five volts). Digital circuit boards run off of flat current.
HP Recommendation HP recommends laser printer technicians wait 30 minutes before removing a circuit boards.
Workaround Solution Over time, a residual electrical charge can build up in your printer. Discharging your printer will drain the charge. With the printer on, unplug and the power switch on and off a few times for 30 seconds, and then plug it back in and power on.
Other Helpful HP LaserJet Printer Support Resources
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