HP Z1 Power Switch Shows 4 Red Flashes and Beeps on Startup

[Dave2U]

We have several HP Z1 workstations in our environment - all are HP Model B5Q12UA#ABA running Windows 10 x64 Professional Build 10.0.15063 (Creators Update). BIOS is HP J52 v2.74 10/21/2016.

Following an automatic restart, one HP Z1 workstation failed to start.  The power button was flashing red (4 times followed by a two second interval) and the flashes were accompanied by four beeps on the same intervals.  The HP Z1 workstation maintenance manual indicates a "Power Failure (power supply is overheated)" as the likely cause.

I have followed the recommendations in the manual as follows:

1.  I have checked all the connections to the power supply to ensure they are secure on the system board.

2.  I removed the hard disk, graphics card, and optical disk drives and powered on the workstation.  The system failed to enter post.

3. I took a known good power supply from one of our other HP Z1 workstations and swapped it for the power supply on the defective unit.  The HP Z1 still failed to enter post and the power button still flashed red 4 times (4 beeps).  I took the power supply from the defective workstation and used it to power up the HP Z1 which I'm using to prepare this post.

In other words, I have determined the issue is not caused by the power supply.  I am at a loss as to what to try next.  Any help would be appreciated.

[steinarV]

Hi,

Have you tried this link: https://h20464.www2.hp.com

[Dave2U]

Thank you, SteinarV.  If you read through my thread, you will see I have studied the HP Z1 Maintenance Manual that provides the same information as the media files you referenced.

My problem is that the diagnostics as presented are inconclusive as to the cause of this issue.  The power supplies are neither overheating or failed.  They have been interchanged with identical workstations and function normally.  Other hardware does not appear to be a factor since all extraneous hardware save the motherboard, processor and memory were removed and the workstation in question failed to get to the post stage.  The 4 red flashes and beeps continued even with the graphics GPU, hard drive and CD/DVD ROM removed.

I suspect it may be related to an undocumented BIOS error, but that is merely a hunch.  I'll leave it to an experienced support engineer to weigh in.