dead PS2 keyboard controller

Station240

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AmiBayer
Joined
Feb 15, 2010
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Country
Adelaide,Australia
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South Australia
Managed to get a loose rivet lodged on the motherboard of my one decent PC. Everything works except the keyboard, which is connected to the only PS2 socket on the board. I checked and the keyboard is getting power, no onboard fuses blown either.

While I couldn't trace where the PS2 port runs to, stupid 8 layer board, there is a chip on the board where the rivet was lodged, a 74HCT125.

The Super IO controller is a IT8720F, which is described as undocumented by the linux community, hence no datasheet anywhere.

Most likely its a damaged SMD 74HCT125, which is a quad tristate buffer. But while I can fix that, I have no idea about the rest of the circuit.

So my question is simple, is there a buffer chip used in the keyboard circuit of modern PCs or not ?
 

Station240

New member
AmiBayer
Joined
Feb 15, 2010
Posts
307
Country
Adelaide,Australia
Region
South Australia
Found a useless PS2 to comm port adapter and used it with my multimeter to trace where it goes. Pin 5 KBDClock connects to multiple pins on the 74HCT125.

Removing the old chip was easy enough, now to find where I can get a replacement SMD version. :coffee:
 
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