Power through HDMI

[roto]

I got an HDMI switcher and when connected to it, a bunch of my MiSTer's components remain powered when my MiSTer is switched off, including my IO board's fan and even my MT32-Pi.

This is a known issue (apparently caused by the Nano not isolating the 5V signal that comes through its HDMI port). Early last year, keith.f.kelly advised a solution: the Cable Matters HDMI repeater: viewtopic.php?t=303. But I just got one and it doesn't work for me - lots of components on my MiSTer, including MT32-Pi and fan, remain powered.

The discussion around keith.f.kelly's post went on to focus on MiSTer's CEC issues, which seem separate to this power thing, so I wanted to pick up on this HDMI power thing and ask: Has anyone found any solutions for isolating the Nano's HDMI port so when a MiSTer is powered off, it's fully powered off?

For example, are there HDMI switchers which don't cause it? This is the one I got: https://www.amazon.co.uk/gp/product/B07SR1S2JL/

Or is there something I can do to an HDMI cable to stop the 5V from getting to my MiSTer?

[darksakul]

Get a short coupler or hdmi extension that has the required pin disabled or removed

There also existing adapters that do the same thing
Look for CEC less HDMI

I wrote a thread in the topic
viewtopic.php?f=33&t=2474&hilit=CEC

[roto]

I read that thread several times - fantastic first post! - but I wasn’t sure if this power issue is also the CEC thing. So they’re down to the same issue, and removing pin 13 will stop my MiSTer being powered up when switched off?

[Ashfall]

I just used a sliver of electrical tape on the cable pin 13. Should work for this too. +5V is pin 18.

[roto]

Thanks! I today got a different HDMI switcher (a Newcare one: https://www.amazon.co.uk/gp/product/B07RY7Y9PR/) and the problem disappeared. Perhaps it was down to my first switcher also acting as a splitter Either way, disabling pin 13 didn’t have any effect, which suggests the CEC issue and the power one are separate. Still, what I can confirm is that getting the right HDMI switcher will avoid it!

[darksakul]

It was hard to know without knowing the exact switcher, and so many switchers look the same on the outside
As various brands share the same fabs and molds/cases but have different innards.

So many things that should be universal on HDMI isn't as there so many ways to implement certain functions.

My MiSTer was powering on my Super Slim PS3 on the Same Switch, turning off the option Control for HDMI on my PS3 solved the issue on the PS3 end of things.

I forgot the setting, but there a setting on some Newer 4K HDTVs that do play havoc with older style reequipment.
And not all HDMI splitters carry this signal forwards.