Questions on VGA on a 2018 Mini

[InuNacho]

I have a 2018 with 2 monitors hooked up. My main display is going through an eGPU with a RX 580 and the other HAS to go through MiniDP on a Dell WD15's USB C dock otherwise I get all kinds of weird startup/sleep issues. I also have a Caldigit TS3+ with Displayport.

I'm trying to run a VGA CRT monitor and later on older projector at a friend's place with my Mini. I have a 25 foot HDMI cable with VGA adapter at the end but it wouldn't drive the monitor, the green light turns on but no picture. I figured both my adapters are not Active and therefore cannot drive the monitor.
I tried the Mini's HDMI, RX 580 HDMI, and Dell WD15 HDMI.

This brings me to my questions, would this even work? From what I remember in the old analog days, VGA had a length of about 10 feet before picture quality started to diminish. Does this still happen with HDMI - Active Adapter (probably has to be powered) - VGA Monitor?
How would I go about keeping the HDMI cable plugged in without displaying an actual image or even showing up on the Mac?

 

[dazey]

What resolution were you running? An active HDMI-VGA converter can certainly do this but you need to know what resolutions the VGA devices can support and make sure you are within that. You also won't be able to play protected content over VGA (e.g. a movie from itunes or whatever apple).

Back in the days of DVI, the DVI connector supported analogue video as well as digital over the same connector (so one could use dumb connectors). Most/all HDMI ports don't support analogue video so you need an active D-A converter.

 

[Amethyst1]

Try using an active MiniDisplayPort-to-VGA adapter hooked up to your Dell dock.

With regards to available resolutions, assuming for the sake of illustration that the miniDP-to-VGA adapter is limited to 165 MHz pixel clock (that's enough for 1920×1200 at 60 Hz refresh, but only if using an LCD monitor and CVT-RB or CVT-RBv2 timings), you should be able to get e.g. 1280×1024 at 85 Hz refresh on your CRT (usng GTF or CVT timings).

What CRT monitor are you using? At what resolution and refresh rate?

 

[Fishrrman]

"I have a 25 foot HDMI cable with VGA adapter at the end but it wouldn't drive the monitor"

Have you considered trying a shorter cable?

 

[InuNacho]

Thank you for your responses. The monitor can go to 1024x768.
I borrowed a random Active adapter from work and can only output 640x480. I guess the adapter dictates the resolution?
I can't use the MiniDP from the WD15 as that drives my secondary display but I can use the displayport on my TS3+.

I can't use a shorter cable, the monitor doesn't sit on my desk as I seldom use it. It comes out to play the occasional Dreamcast game. It sits on a cabinet on the other side of the room and the cable wraps nicely under some other furniture.