HP LaserJet II Serie Manual De Instrucciones página 216

HP 33440/HP 33449 COMBINED SERVICE MANUAL
"51 ERROR" Message
Two displays, 41 ERROR and 51 ERROR, i ndimte a laser beam detect problem. The 41 ERROR is
displayed when the beam is "lost" for less than 2 seconds. An error condition of greater than 2
seconds will result in a 51 ERROR message.
A
41
ERROR (temporary Beam Detect Error) may occur during laser scanning operation. This
error results when the beam detect signal falls outside the timing window established by the DC
Controller PCA. If this situation occurs longer than an intend of ~o seconds, a 51 ERROR beam
detect malfunction will occur,
The BEAM DETECT (~) signal is the horizonti synchronization signal indicating the beginning
of a scan line. Once beam detect synchronization is achieved, video data may be transferred from
the Interface/Formatter PCA to the DC Controller PCA to turn the laser diode on and off, thereby
writing print data (in the form of dots) on the photosensitive drum.
At the beginning of printer operation, the DC Controller enables the Laser/Scanning Assembly
and sets up a timing window. The DC Controller expects to receive a beam detect signal during
this window. Once received, dl data transfer is synchronized from the last beam detect signal.
A "Beam Detect Malfunction" indicates that the laser beam is not being detected. Beam detection
occurs during the scanning process as the laser light strikes the beam detect mirror. The mirror
reflects this light to a fiber optic cable that carries it to a sensing diode on the DC Controller PCA.
To prevent possible exposure to laser light, a safety interlock shutter has been incorporated into
the design of the Laser/Scanning Assembly. The Laser Shutter Arm is located on a pivoting shaft
below the Laser/Smnning Assembly. When the Top Cover Assembly of the printer is open or the
EP-S Cartridge is missing, a blocking shutter within the Laser/Scanning Assembly blocks the path
of laser light. A small tab on the edge of the EP-S Catiridge must contact the pivoting shutter
lever before laser light is allowed to exit the laser ~vity.
warning
Although the infrared laser beam is invisible, eye damage can occur if direct
9
u
or indirect (reflected) eye contact with the laser beam should occur. Heed all
CAUTIONS and WARNINGS when working with the laser unit. Be careful when
the fiber optic beam detect cable is detached since the laser light transmitted
through the cable can also cause eye damage.
7-52