#57 - Agilent E3641A power supply repair HD

This power supply had non-functioning front panel (display, keypad and encoder). It turned out that three chips were dead in the front panel module: Intel 80C51 micro-controller, HV518PJ VFD driver and 74HC02 quad NOR gate. Fixing this took quite a bit of SMD and through-hole rework, and quite a bit of luck, especially finding the firmware for the micro-controller. Forum: http://www.eevblog.com/forum/repair/agilent-e3641a-repair/ Replacement parts on DigiKey: AT89S51: https://www.digikey.com/product-detail/en/AT89S51-24JU/AT89S51-24JU-ND/1118890 HV518PG https://www.digikey.com/product-detail/en/HV518PJ-G/HV518PJ-G-ND/4902550 Firmware 34401-88804 rev01: http://www.ko4bb.com/getsimple/index.php?id=download&file=HP_Agilent/Agilent_34401A_E3646A_Display_board_MCU_firmware_dump_EPROM_34401-88804_RE-34401-88804.zip 34401A multimeter service guide with display and keyboard schematic : http://literature.cdn.keysight.com/litweb/pdf/34401-90013.pdf