I had a case years back where it seemed like some BIOS bitrot broke the com ports, and the chip would not take a flash any longer, but things worked again with fresh BIOS chip and BIOS.
Unicorn herding operations are proceeding, but all the totes of hens teeth and barrels of rocking horse poop give them plenty of hiding spots.
rain wrote on 2023-10-30, 12:41:so that i undersfand, all serial connectors not same?
Yes. There are practically two "standard" ways how the MB COM connector and compatible bracket are wired (AT/Everex vs DTK/Intel). There are possibly some proprietary connectors too, but those two are by far the most common.
Easiest way to check if your bracket is compatible or not is to plug in the connector and measure if you get ground on the pin 5 of the COM port. If you don't get ground on the pin 5, your bracket is of the wrong type and you need to solder the connections correctly in the bracket.
Of course there is the possibility that the IO chip is fried on your MB and COM port doesn't work because of this. I still find the wrong connection the most likely reason.
