Agilent DSO9104A Scope stopped booting up. Advice On way forwards.

[magnetchief]

Hi, I have a nice 1GHz Infiniium Scope that's stopped working.
It was fine earlier in the week, now its non functioning.

Things I have tried.
1. Powering on, the fans and control knobs spin and light up momentarily. Then nothing.
2. Opened up the case to check the battery on the motherboard, a simple lithium cell. It read 3v, but replaced it anyway. No change.
3. There is a series of fault finding leds inside of the case. When it fails to boot LEDs #1 & 2 remain illuminated in Sequence #2.
From the attached guide 1 & 2 are fault type SEQ2: U497. I think this is an external fault as I read the troubleshooting guide in https://xdevs.com/doc/HP_Agilent_Keysight/54904-97014%20Infiniium%209000%20Series%20Oscilloscope%20Service%20Guide%20%5B128%5D.pdf

4. I checked the various connectors and cables, they all look secure.

Any thoughts before I ship this off ?  Much appreciated.

[magnetchief]

Photo showing led sequence.

[free_electron]

check the power rails. 1.2 or 1.8 volt is missing. these are typically modules on the acquisition board. i doubt those die. most likely the input to those modules is missing. if i remember correctly there are surface mounted fuses on the board. check those.

[magnetchief]

Many thanks, will investigate further.

[magnetchief]

Checked what I could within my ability.
The voltages from the accusation board looks fine, as far as I can tell.
I could not find any onboard fuses except one deep in the main power supply.

I'm thinking I'm going to have to bite the bullet and send it back to Keysight for a repair. $5300 qute.

[salvagedcircuitry]

Did you have any luck troubleshooting and repairing your DSO9104 oscilloscope?
It seems your 1.2v rail is problematic. Were you able to check the second sequencer? Maybe some type of failure between different stages of dc-dc conversion?
Thanks