HP LASERJET ENTERPRISE CP4020 - Troubleshooting and Diagnostics; Troubleshooting Process and Checklists; Power and Engine Diagnostics; Manual Sensor Testing

Lifter-drive assembly (optional paper feeder) .................................................................. 230
Remove the lifter-drive assembly (optional paper feeder) .............................. 230
Pickup motor assembly (optional paper feeder) ............................................................. 231
Remove the pickup motor (optional paper feeder) assembly .......................... 231
Controller PCA (optional paper feeder) ........................................................................... 232
Remove the controller PCA (optional paper feeder) ....................................... 232
3 Solve problems
Solve problems checklist .................................................................................................................. 234
Menu map ........................................................................................................................................ 236
Troubleshooting process .................................................................................................................. 237
Determine the problem source ........................................................................................ 237
Pre-troubleshooting checklist .......................................................................... 237
Troubleshooting flowchart ............................................................................... 239
Power subsystem ............................................................................................................ 240
Power-on checks ............................................................................................. 240
Power-on troubleshooting overview ............................................... 240
Tools for troubleshooting .................................................................................................................. 242
Individual component diagnostics .................................................................................... 242
LED diagnostics .............................................................................................. 242
Understand lights on the formatter ................................................. 242
Engine diagnostics .......................................................................................... 243
Defeating interlocks ........................................................................ 243
Disable cartridge check .................................................................. 244
Engine-test button .......................................................................... 244
Paper-path test ................................................................................................ 245
Manual sensor test (special-mode test) .......................................................... 246
A TOP (top of page) sensor ............................................................ 247
B and C loop sensors ..................................................................... 248
D fuser delivery sensor ................................................................... 249
E duplex re-pickup sensor .............................................................. 250
F output bin full sensor ................................................................... 251
I developer alienation ..................................................................... 252
J fuser pressure-release sensor .................................................... 253
K primary transfer-roller-disengagement sensor ............................ 254
L media sensor .............................................................................. 256
M front-door switch ......................................................................... 257
N right-door switch .......................................................................... 258
Manual sensor test 2 (special-mode test) ....................................................... 259
O Tray 1 paper present sensor ...................................................... 261
P Tray 2 paper present sensor ....................................................... 262
Q Tray 2 paper surface 1 and 2 sensors ........................................ 263
R Tray 2 paper size switches ........................................................ 264
x ENWW