Tom and Lisa P wrote:
> >Tom P aka "Mad Dog" asks:
> >>Does anyone know which chip on the 3400 controlls the ADB ?
> >
> >Opening the PB3400 devnote . . . the "Architecture" block chart on page
> >11 shows the PMU IC with ADB responsibilities. Then on pages 15 and 16 we
> >find this helpful info:
> >
> ><quote>
> >Power Management Unit
> >The power management unit (PMU) is a 68HC05 microprocessor that operates
> >with its own RAM and ROM. The PMU IC performs the following functions:
> >controls sleep and power on and off sequences
> >controls power to the other ICs
> >controls clock signals to the other ICs
> >supports the ADB
> >scans the keyboard
> >controls display brightness
> >monitors battery charge level
> >controls battery charging"
> ></quote>
> >
> >does any of that help?
>
> Well, that leads me to a general direction. Now I must peruse
> ICMaster and find out what a 68HC05 looks like.
>
> >What the heck are you up to now? <G>
> >
> >Dan K
>
> I have a couple of dead 3400 motherboards that have no ADB/trackpad,
> so I will just swap around ADB chips. Trouble is , I never knew
> until now what it was.....
>
> thanks,
>
> Mad Dog
>
Tom,
If you're looking at the top side of the motherboard there 2 large high
density chips near the center of the board, one of them is labeled PMU that is
the bad chip, I also have several bad 3400 logic boards with this same
problem, the primary symptom of the problem is usually that the computer won't
wake up, even after a hard restart, this is due to the multfunctionality of
the chip. I have been unable to locate a source for this part and since all
the boards I have are exhibiting the same symptoms part swapping is not a
solution.
Roger
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