Power leak via graphics board to Cyrus HD led connector

AmigaOne X5000 platform specific issues.

Power leak via graphics board to Cyrus HD led connector

Postby Roland » Mon Apr 01, 2019 9:57 pm

I use a HDMI->VGA adapter (Deltaco) between my Radeon card and monitor. The adapter needs USB power to work, but as the power output of X5000's USB ports is so irregular during the early bootup phases, the adapter starts to work only after AmigaOS has already started to load (discussed already in other thread here).

To fix this I tested to use an USB 3.0 Hub (Hama) to input power to the adapter. The adapter itself worked ok, but there was also a VERY strange side effect... Somehow the HARD DISK POWER LED (on X5000's front panel, connected to the Cyrus board) got extra power, too! Normally, when my X5000 is in the stand-by state (power supply swithed on, a red and a green led glowing on the Cyrus board) but the machine is not yet on, the hard disk led is totally off. But now, when I had this USB Hub on and connected to the HDMI-VGA adapter, the HD led glowed, faintly but noticeably! When I then switched the machine on and the led started to react to HDs, it was visibly brighter than usually...

I would now like to stress that the USB Hub was NOT connected to any USB port, or any other part of my machine, except the HDMI->VGA adapter!

So... How is this kind of 'leak' possible? And is there a risk to the Cyrus board? (Haven't used the Hub after noticing this, just in case!)


Here is a diagram to clarify the 'leak path':

USB HUB > HDMI-VGA adapter > Graphics board > PCIe connector - Cyrus board - HD led connector > Led
- Roland -
Roland
 
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