E93839 is an Underwriters Laboratories (UL) file number registered to (Hon Hai Precision Industry Co., Ltd.). When you see "E93839" printed or etched onto a PCB, it simply means that the bare printed circuit board itself complies with UL safety and flammability standards (such as the UL 94V-0 standard for fire retardancy).
Verify the motherboard is receiving power. Check the CMOS battery (3V DC). e93839 motherboard schematic updated
The standby voltage rail that remains active as long as the power supply is connected to AC mains. This powers the SIO chip and the Southbridge/PCH standby circuit, allowing the board to detect the power button press. Secondary Derived Rails E93839 is an Underwriters Laboratories (UL) file number
PWROK ). Use the updated timing diagrams in the schematic index to check these states in chronological order with an oscilloscope or multimeter. Check the CMOS battery (3V DC)
Full engineering schematics (circuit-level diagrams showing resistors, MOSFETs, and voltage rails) are rarely released to the public by Dell or HP. Dell OptiPlex 760 Service Manual