Hey All,

I came across this EPoX EP-3VSA2 mobo recently, it seemed to boot OK but the keyboard didn't work. Quick health check showed all but 4 electrolytics were bad so gave it a recap hoping the keyboard might come good but no such luck.
I've been giving myself a crash course on the inner workings of PS/2 protocol but have maxed out my troubleshooting skills, would love some pointers if anyone knows what is going on!

Symptoms:
Without keyboard attached, the board boots but the pc speaker has rapid, intermittent beeps. Boot device will continue as normal to dos\windows, no keyboard input works.
With a keyboard attached, the board boots as normal with normal POST beeps from the PC speaker, no keyboard input. Super occasionally (1 out of 20 times type of thing) keyboard will work on and off, one key will register but the next 10 wont, etc.

Troubleshooting:
PS2 5v and GND are OK.
Tried multiple keyboards.
Desoldered PS2 ports with same results.
I've chucked my million year old scope on the clock line and can see what looks like a lot of noise when no keyboard is attached, the pc speaker seems to beep in-line with the peaks on the scope.
With a keyboard attached, the scope shows the clock line starting out high, powering on the board makes the line go low-high-low where it settles in a low state.
With the board powered off both clock/data lines on the PS2 port show normal communication when a key is pressed. (voltage to the port is OK with the board powered off)
The board also powers on OK with a keypress on the keyboard. When a keyboard is attached I can always enter BIOS setup but keys become unresponsive after that.

From what I've researched, the clock should always be high and a keypress will result in a series of low pulses which the first falling edge 'triggers' a keypress, it seems my board is held low when a keyboard is attached or full of noise when no keyboard attached. Maybe there's a pull-up resistor or something simple I'm missing?

Attached a photo where the purple traces are clock and orange data. There's what I assume are some inductors that read 0-ohm, 472 and 202 I assume are resistors and they read as such on my DMM. The C470 component I assume is a capacitor pack but I can't read the fine pads with my bulky ESR meter. The three legged components I'm guessing are transistors, not confident enough with my skills to know if these are good or not.

https://youtube.com/shorts/YUWjkqLXvng - scope clock line no kb
https://youtube.com/shorts/xfBIHEdULwA - scope clock line with kb

Anyone have some tips of where to head next?