Bryan Walter wrote:
> Hi List,
>
> I've recently acquired a PowerBook 3400c (200MHz model) which has quite
> a number of interesting problems. I'm anxious to get new parts in it
> and restore its health, but I'm not quite sure what's wrong.
>
> First, the booting is sporadic. Sometimes it doesn't want to boot at
> all, other times it will boot spontaneously when the AC adapter is
> plugged in. Seems to me that it is some type of power problem, as the
> OS can't get any solid reading on the battery or the battery time
> remaining although the battery does work. While it is plugged in to
> the AC power, there is also a high-pitched whining buzz that comes from
> the PowerBook. It sounds like it is coming from right below the
> trackpad, where the PMU board is located.
>
> Also, there seem to be issues with the motherboard. It started out
> that the PowerBook just won't make any sound whatsoever. No boot
> chime, nothing. It doesn't make sound through external speakers either
> or take a signal from a microphone that is plugged in (although the
> internal mic seems to pick up sound fine). I started testing it one
> day, and I discovered that the ADB, VGA, and serial also don't work,
> and I presume the SCSI probably doesn't either although I don't have an
> adapter to test it. Another interesting thing is that the modem most
> definitely dials out and works, but the ethernet on the same card
> doesn't work at all.
>
> All this has led me to believe that there is a problem with the PMU
> board, and possibly with the motherboard as well. Trouble is, I don't
> know where to find either part without paying through the nose so I
> want to be sure what the problem is so I don't buy parts I don't need.
> Anyone have any ideas or seen anything similar with another 'Book?
>
> Thanks,
>
> Bryan
>
Brian,
Reset the power manager(push the reset buton on the rear of the
machine),Zap the PRAM, Check the PRAM battery, Replace the power supply
board, if none of these work, your 3400 is developing sleeping sickness,
the problem is the PMU chip ( a 68HC05) on the main logic board, along with
it's PMU functions:
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
So when this chip starts to malfunction, it is time to replace the
logic board as I have been unable to find a source for the Apple programed
part andd have 3 units with the same problem.
Good Luck
Roger
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