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Agilent N9320B stuck at boot (frozen at Keysight splash screen)

Question asked by analogRF on Nov 18, 2019
Latest reply on Nov 25, 2019 by LukasM

recently I got this N9320B that does not boot. It gets stuck at the Keysight splash screen after it passes the Agilent splash screen
There was nothing detected on the USB and LAN connections at the back either
So I opened it up and first all voltages on the back plane motherboard are fine (clearly marked test points :-+). So I got the main DIF board out, which contains the CPU, firmware, and the entire IF and RBW filters and DSP sections, took it out of its shield and installed it back so I can do some limited measurements on the board. 

There are quite a number of DC-DC converters and voltage regulators on this board which I identified and measured all of them. ALL are OK 

I found a MAX232 chip and observed some activities on the pin 11 (T1 input) and on the corresponding pin 14 (T1 out). So I connected my Bus Pirate to pins 11 and 12 (on the TTL side) of the MAX232 and set up a UART connection with 115200 baud and bingo  :-+ I got the boot prompt. Please read my results in the attached txt file. You can see how the boot process proceeded until it stopped.


I cannot quite figure out what my problem could be. Maybe some experts out there can interpret the results and tell me how to proceed.

My guess is that either the memory chips (SRAM) are bad which would be a very good news or the FLASH EPROM is corrupted in which case i dont know what to do.