Agilent 34411A repair "FPGA COMMS FAIL"

[Fabi1]

Hi all !
I succeed to repair an Agilent 34411A DMM, I share the solution if someone get the same problem
There was an "FPGA COMS FAIL" error display on power up, it comes from 3,3V power supply, provided by U800.
The problem disappear when I put my finger on U800, I add tin-lead solder on each SOT23-6 pin of U800, then it works fine !
see attached files, 34410A schematics (almost same as 34411A ?), and pictures to localize U800
Fabi1. Agilent_34410A_schematics.pdf (848.8 kB - downloaded 1259 times.)