The customer sent a HP 3458A eight-bit half-multimeter for repair, and the repair fault was reported as a self-test error, and the panel was seriously broken and damaged. Test the instrument and confirm that the fault is consistent with the customer's repair report, and transfer it to the maintenance department for maintenance. The following is the maintenance process of HP 3458A eight-bit half-multimeter: Report failure Self - check error, panel serious breakage! Fault determination After getting the instrument, press the self-test key on the panel after power is turned on, and the self-test of the instrument reports error 214. After testing, it is found that the A1 decoding board and control board units of the instrument are damaged, resulting in equipment failure. At the same time, the panel is broken, and the keys have no effect. Maintenance After clarifying the fault point, the engineer will carry out maintenance, repair the decoding board and control board, replace the damaged components, replace the face frame, and clean and test the whole machine. After repair, the boot is normal, the self-test has no error, the function is normal, and the index is qualified. After a period of aging test, the instrument is handed over to the test department for detailed inspection.