HP 8550 Service Manual - Page 521

Faults not identified by error codes No ac power to the copy module Cause Power plug Main power source Leakage breaker (ELCB1) Step 1 2 3 4 Leakage 5 breaker (ELCB1) Power cord, 6 noise filter PCB Copy module 7 rear power switch (MSW1), wiring Checks Yes/No Action Is the power plug connected to the NO power outlet? Connect the power plug. Is the rated ac voltage present at NO the power outlet? Advise the user to correct the problem. Is the rated voltage present YES between J1101-1 and J1101-3? Go to step 7. Is the switch of the leakage breaker in the copy module at OFF (LOAD) position? YES Check the ac power system unit and line; if faulty, replace the part. If normal, shift the switch of the leakage breaker to ON (LINE) side. (See note below.) Is the resistance 0 Ω between both NO terminals of the leakage breaker (ELCB1)? Turn on and off (shifting to LINE and LOAD) the switch of the leakage breaker, and check it for electrical continuity. If it is still not 0 Ω, replace the leakage breaker. See Figure 413. Replace the power cord or the noise filter PCB. Is the problem corrected? YES Replace the problem part. Connect the probes to both NO terminals of the copy module rear power switch (MSW1). Does the YES resistance change to ∞Ω when the switch is turned on? Replace the copy module rear power switch (MSW1). Check the ac ac power line and connectors. Note The leakage breaker has two functions, serving as a circuit breaker and cutting of power in response to leakage. Be sure to make line-toline and line-to-chassis checks for short circuits even if there is no fault in the leakage breaker. EN Copy module troubleshooting 519