HP 8550 Service Manual - Page 464

Image fault troubleshooting Initial checks Environment l The voltage must be ± 10% of the requirements noted in chapter 1 of this manual. l The copier must not be in a high-temperature and high-humidity environment (near a water faucet, water boiler, humidifier), and it must not be in a cold place. There must be no source of fire nearby, and the copier must not be subjected to excessive dust. l The copier must not be exposed to ammonium gas. l The copier must not be exposed to direct sunshine. As necessary, curtains must be provided for nearby windows. l The room must be well ventilated. l The copier must be kept level. l The power plug of the printer unit must be connected to the copy module, and the power plug of the copy module must be connected to the power outlet. Originals Check whether the problem is related to the original or to the copier. A diazo (blueprint) original or an original with high transparency can produce copies that can be considered "foggy." An original prepared in light pencil can produce copies that can be thought of as "too light." Also, very often a "bad copy" is simply a faithful reproduction of a bad original. Note: Second- and third-generation copies (copies of copies) deteriorate rapidly in terms of copy quality. Parts Check the copyboard cover, copyboard glass, and standard white plate for dirt and scratches. If any are soiled, clean them with a moist cloth; if any are scratched, replace them. Printer assemblies checks Check the secondary pre-transfer assembly and separation static eliminator for dirt and faults (scratches, deformations). Clean the charging wires of the secondary pre-transfer charging assembly and separation static eliminator. Further, clean the density sensor and the pre-exposure LEDs. 462 Chapter 7 - Troubleshooting EN