"No Signal" on LG 34WQ75C-B USB-C monitor - all other devices work on the LG and the Deck

[MarcTV]

Hi,

there are already quite a few discussions regarding the incompatibility of the Steam Deck with USB-C connection from LG.

https://steamcommunity.com/app/1675200/discussions/1/3416556480597288512/
https://www.reddit.com/r/SteamDeck/comments/1343rd1/steam_deck_not_working_with_lg_usbc_monitor/

But the Steam Deck support told me I should open a new discussion here. I can connect any device on the USB-C connection of my LG monitor like Macbooks or Windows Laptops and they all work. When I connect the Steam Deck then the USB-Hub and power delivery works over USB-C for the Steam Deck but not the video signal. Even audio seems to work over the speakers of the LG when the Steam Deck is connected. And yes, the monitor offers "DP Alternate Mode" over USB-C: https://www.lg.com/hk_en/monitor/lg-34wq75c-b

I asked LG for support and they say: "if the monitor works an every other hardware via USB-C then the Steam Deck team has to look into this. Maybe this is a driver problem".

My Steam Deck works on every other USB-C monitorwith power delivery from Lenovo to Dell. Every USB-C-Hub works, too. The LG provides 90 watts. So that no problem, too.

So, any idea? I tried everything the support told me: battery storage mode, switch off and power on with USB-C-cable attached, Desktop Mode, Steam Deck Mode, different USB-C cables. Any help from anyone is much appriciated.

[germanicianus]

As a workaround try to do it old-school - connect the monitor via HDMI or DisplayPort - using either a dock or an adapter.

Btw. - I stopped buying any LG device over a decade ago when their support refused to give out a simple firmware file which I could have used to fix my DVD player. No support -> no money.

[MarcTV]

I think this is a problem with the Steam Deck. But HDMI does not work because even the official dock has problems using the full ultra wide solution with 60 hz via HDMI. It works via usb-c with other monitors.