HP LaserJet 4 Service Manual - Page 243

MP/PC/LC Tray 1/2/3 LOAD Message

Page 243 highlights

MP/PC/LC (Tray 1/2/3) LOAD Message The conditions that result in MP/PC/LC LOAD or (TRAY 1/2/3) messages are: • The absence of any input tray. • The absence of media in either tray. • The tray size switches may be defective and not recognize the presence of the paper tray. The tray is sensed as the tray-identifier tabs contact one or more of the three tray identifier microswitches. • The Universal Tray paper size dial setting does not match the installed paper. The MP/PC/LC LOAD message is also generated when the user or software requests a paper size other than that installed. The Paper Sensing Arms are located in the paper input areas of the printer. During normal operation, the Paper Sensing Arm flags rest on the media installed in the paper tray. The Sensing Arm flags are attached to shafts. The opposite end of the shaft is a photointerrupter that rotates through the sensors on the Paper Control PCA. These sensors are: • PS4 Paper out-MP tray. • PS2 Paper out-PC tray. • PS6 Paper out-Lower Cassette. • PS7 Paper out-Envelope Feeder. The presence of paper in the paper tray is sensed by the paper sensor arm. When paper is in the cassette, the sensor arm rests on top of the paper in the tray. At this point, the sensors are not blocked. When the tray is empty, the arm swings through its travel. The photointerrupter attached to the paper sensor arm shaft rotates and blocks the sensor diode. Troubleshooting 7-13

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MP/PC/LC (Tray 1/2/3) LOAD Message
The conditions that result in
MP/PC/LC LOAD
or (
TRAY 1/2/3
)
messages are:
The absence of any input tray.
The absence of media in either tray.
The tray size switches may be defective and not recognize
the presence of the paper tray. The tray is sensed as the
tray-identifier tabs contact one or more of the three tray
identifier microswitches.
The Universal Tray paper size dial setting does not match
the installed paper.
The
MP/PC/LC LOAD
message is also generated when the user or
software requests a paper size other than that installed.
The Paper Sensing Arms are located in the paper input areas of
the printer. During normal operation, the Paper Sensing Arm
flags rest on the media installed in the paper tray. The Sensing
Arm flags are attached to shafts. The opposite end of the shaft is
a photointerrupter that rotates through the sensors on the Paper
Control PCA. These sensors are:
PS4 Paper out-MP tray.
PS2 Paper out-PC tray.
PS6 Paper out-Lower Cassette.
PS7 Paper out-Envelope Feeder.
The presence of paper in the paper tray is sensed by the paper
sensor arm. When paper is in the cassette, the sensor arm rests
on top of the paper in the tray. At this point, the sensors are not
blocked. When the tray is empty, the arm swings through its
travel. The photointerrupter attached to the paper sensor arm
shaft rotates and blocks the sensor diode.
Troubleshooting 7-13