Lexmark T522 Service Manual - Page 72

4520-xxx FRU 7 LVPS Fuse F1 - Continues to blow after LVPS installed in the printer. 8 LVPS 9 Engine Board Action Replace fuse F1 if necessary. Turn the LVPS on/off switch off and connect the AC line cord and turn the LVPS on. CAUTION: Before checking fuse F1 turn the LVPS Off and disconnect the AC line cord. Check fuse F1. If the fuse is blown, replace the LVPS. CAUTION: Before making any measurements on the LVPS output connector, observe all necessary safety precautions before applying AC power. Measure the voltage on LVPS output connector CN3 (Pin 1, 2, 10, or 11). The voltage measures +5 V dc. If incorrect, replace the LVPS. Turn the printer off and disconnect all the cables from the engine board. Check for +5 V dc at the engine board test point. If incorrect, replace the FRUs in the following order: 1. Engine board 2. Interconnect board If correct, turn the printer off and reconnect one cable at a time until you find the defective assembly. Service Tip: A short or low resistance load that is attached to the engine board can cause the LVPS to over-current and shut the +5 V dc supply down to 0 V dc. 2-44 Service Manual