IBM 7985 Problem Determination And Service Manual

v Follow the suggested actions in the order in which they are listed in the Action column until the problemis solved.v See Chapter 4, “Parts listing, System x3655, Type 7985 and 7943,” on page 93 to determine whichcomponents are customer replaceable units (CRU) and which components are field replaceable units(FRU).v If an action step is preceded by “(Trained service technician only),” that step must be performed only by atrained service technician.System event/error log message Action+12V planar fault 1. If the OVER SPEC LED on the light path diagnostics panel islit, or any of the four power channel error LEDs (A, B, C, or D)on the system board are lit, see the entries aboutpower-channel error LEDs in “Power problems” on page 46.(See “System-board LEDs” on page 17).2. If the actions in “Power problems” on page 46do not identify adefective component, complete the following steps:a. Remove the power supplies. Replace the power suppliesone at a time, restarting the server each time, to isolate afailing power supply.b. If the server fails to start, replace the power backplane.Restart the server.c. If the server fails to start, (trained service technician only)replace the system board.+5V critical over voltage fault 1. Remove the following devices, which are powered by 5 volts:v All PCI adaptersv USB devicesv CD-RW/DVD drivev Tape drive, if one is installedv Hard disk drive backplane2. Reinstall each I/O device removed in step 1, one at a time,restarting the server each time, to isolate a defective device.Replace any defective device.3. If the error continues, replace the power backplane. Restart theserver.4. If the error continues, (trained service technician only) replacethe system board.+5V critical under voltage fault 1. Remove the following devices, which are powered by 5 volts:v All PCI adaptersv USB devicesv CD-RW/DVD drivev Tape drive, if one is installedv Hard disk drive backplane2. Reinstall each I/O device removed in step 1, one at a time,restarting the server each time, to isolate a defective device.Replace any defective device.3. If the error continues, replace the power backplane. Restart theserver.4. If the error continues, (trained service technician only) replacethe system board.70 IBM System x3655 Type 7985 and 7943: Problem Determination and Service Guide