All function failure, the problem may be the part in power. Teardown check D401 rectifier output voltage is normal, light coupling PC401, PC402 are normal, but IC404 (LM340T12) no normal 12 v voltage output, explains the power part is not really normal. Check T401 peripheral components, diodes D453 have been found short circuit breakdown, and put on a same diode electricity after commissioning, fault phenomenon disappears, and send and receive fax copy is normal.dSAservice manual download site