Xerox Phaser 790 Service Manual page 128

007-713 Tray 3 Paper Size Not Detected RAP
The Control Logic detected that the wrong size paper is feeding from Tray 3.
Initial Actions
Ensure that the paper in Tray 3 is properly installed and that the tray side and end guides are
positioned to touch the paper in the tray.
Procedure
Switch off the power. Disconnect the Power Cord. Remove the Size Switch PWB (PL 13.3).
Place the Size Switch PWB so that it does not short circuit to the machine frame. Connect the
Power Cord. Disconnect PJ 236 from the Size Switch PWB. Switch on the power. There is +5
VDC from J 236 pin 1 to machine ground.
Y N
Go to Flag 2. Check the wires for an open or a short circuit to ground. The
good.
Y N
Repair the wires.
Replace the MCU PWB (PL 11.2).
A
Table 1 Tray 3 Size Sensing Switch PWB
PAPER SIZE PAPER SIZE SW
SW1 SW2
Tray Out OFF OFF
Ledger (SEF) OFF ON
A3 (SEF) ON OFF
Letter (LEF) OFF ON
B5 (LEF) OFF ON
Legal (SEF) OFF OFF
A4 (LEF) OFF OFF
B4 (SEF) OFF ON
Status Indicator RAPs
007-713
A
Connect PJ 236 on the Size Switch PWB. Actuate and hold switches SW1 and SW3 on the
Size Switch PWB. There is +1.57 ±0.10 VDC from J 236 pin 2 to machine ground.
Y
Actuate and hold switches SW2 and SW4 on the Size Switch PWB. There is +3.13 ±0.10
VDC from J 236 pin 2 to machine ground.
Y
wires are
Replace the MCU PWB (PL 11.2).
ANALOG
VOLTAGE OUT
SW3 SW4
OFF OFF (+) 4.76 VDC
OFF OFF (+) 3.45 VDC
ON OFF (+) 1.57 VDC
ON ON (+) 2.49 VDC
OFF ON (+) 3.13 VDC
ON OFF (+) 4.09 VDC
ON ON (+) 3.77 VDC
ON OFF (+) 2.81 VDC
10/00
2-114
N
Go to Flag 1. Check the wires for an open or a short circuit to ground. The
good.
Y N
Repair the wires.
Replace the Size Switch PWB (PL 13.3).
N
Go to Flag 1. Check the wires for an open or a short circuit to ground. The
good.
Y N
Repair the wires.
Replace the Size Switch PWB (PL 13.3).
wires are
wires are
Initial Issue
Phaser 790/DocuColor 2006