rasz_pl wrote on 2023-06-26, 06:49:
yay wrong pins measured 😀
>I see the signal changing [EDIT]in the oscilloscope[/EDIT] when typing something.
so now we need to see that signal, and as you say voltage on pins 14(1) of MC1488, ideally both at the same time while typing in terminal
the signal on pin 14 and 1 of the MC1488, fyi it's an SN75188 on OP's cards, shouldn't change much aside from any possible interference or fluctuations.
I can't recall if it was mentioned that another psu has been tried ( see that's why a summary would've been so great ! ). I'm gonna assume he already did that.
and to re-itterate the card works in another computer, so that leaves the mainboard.
pshipkov, did you find and try a serial card or multi io card with more chips? ie not one component that does most.
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