Ben Wrote:
>The keyboard should send a pair of bytes on pin 1 when power is first
>applied - the keyboard controller does a self check and sends this 'I'm
OK'
>sequence when everything passes (I would have been able to tell you what
the
>bytes were, but someone's tidied my desk while I've been away. E0 FF or
F0
>FE ring bells, for some reason). When the PC is turned on, if the three
>status LEDs blink the keyboard is getting power and has sent those two
>bytes - there's no way that the keyboard can be powered up without that
>happening (even my minidisc deck does it).
Check for Bytes? I'm not sure how I'd do that. I did use my analog
volt/ohmmeter to check the Pins and I found the following readings and they
match the specifications:
1. keyboard data (reads 5.0V)
2. No connection (0V)
3. Signal ground (0V - continuity to ground)
4. Fused supply voltage (reads 2.9V)
5. Keyboard clock (reads 5.0V)
6. No connection (0V)
Since I did get an error "keyboard clock line failure" I expected there
would be a problem with pin 5. But I'm getting 5 volts there.
>As an aside, I meant to say this earlier but forgot - if you've got a
>motherboard spare, try swapping the keyboard chip over (it's a ROM IIRC,
so
>quite large and usually with a sticker on the top - I think mine are
>AnyKeys). I've seen machines where that chip let out the magic smoke, and
>worked fine when switched with a chip from a dead motherboard.
I may have to pull out the MB to do this - What I first thought was the
BIOS keyboard chip turned out to be the onboard video chip. It is right
next to the BIOS chip and looks identical. I HOPE this board has a keyboard
controller chip and it's not integral with the board.
Thanks Ben
The struggle continues....
Dave
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