Further to my two earlier posts on this subject, I got a few offlist posts
too from well-intentioned fellow listers indicating the correct way to reset
the Power Manager. I should have forsaken attempted brevity to better
outline what I've only learned empirically.
I assume my esteemed fellow listers follow all textbook procedures for
resetting the Power Manager and PRAM so I did not bother to review those
techniques. Tim and I are both of the opinion that the textbook application
of PM / PRAM resets, particularly in the case of the 2400, often does not
cure the corruption problems. Note that Command-Option-P-R does not reliably
zap all the PRAM, so if a SCSI device or modem doesn't show up, DON'T assume
it's a bad SCSI port or modem. Tech Tools and certain shareware utilities
can zap the residual unzapped PRAM. And on Power Manager resets, I recently
detected a hairline separation of one of the black/red wires leading to the
PM switch from the inside of my 2400. A pinpoint solder job fixed that but
it was a big surprise to find and certainly 100 PM resets wouldn't have had
any effect. I only found this out in my latest bout with the "2400 green
light of death" because it curiously wouldn't go out when the PM button was
depressed.
My earlier posted recommendations should only be applied after trying
Apple's textbook procedures, which I erroneously and impatiently assumed
would have been already automatically tried by anyone experiencing a more
stubborn case of the "2400 green light of death". Periodically here have
been "panic" posts of this problem over the past year or so, and I suspect
at least some of these cases were not hardware issues, even though
motherboards or other components were replaced. It does not surprise me that
MB problems were sometimes just a fuse, but it is very difficult to find an
Apple repair tech who will do a board/component level repair.
Again, try my recommendations ONLY after exhausting ALL other options and
short of sending it out for a (more expensive, possibly unnecessary) repair
or consigning it to 2400 heaven with a full complement of donor organs for
other unhealthy 2400s. There are usually a number of parts buyers listed on
the 2400 website.
---
Sidney Ho
[EMAIL PROTECTED]
----------
>From: "Sidney Ho" <[EMAIL PROTECTED]>
>To: [EMAIL PROTECTED]
>Subject: Re: 2400 green light of death
>Date: Wed, 16 Feb, 2000, 6:18 PM
>
Timothy A. Seufert <[EMAIL PROTECTED]> wrote:
>> Don't forget:
>>
>> SIMPLER -- Reset the PMU by playing with the reset button on back.
>> The correct procedure for PMU reset is: remove battery, plug in AC.
>> Hold down reset button for 20-30 seconds, release. It may take a lot
>> of repetitions for this to work!
>
> Quite right! But, like you, I tend to find the orthodox treatment nearly
> useless. After many series of 10-12 attempts in the past, usually
> characterized by 2400 behavior increasingly resembling a terminal hardware
> problem, I usually just go straight to this procedure now and skip "SIMPLER"
> after one or two attempts. I also let it sit more than a few hours because I
> suspect a residual charge even after the green diode is extinguished. It
> seems the longer you "age" a PM / PRAM corrupted 2400, the easier it is to
> revive. Obviously after I leave mine in pieces, inertia takes over as I use
> another PB. Come to think of it, I've probably had to mess with PM / PRAM
> resets more with a 2400 than all of the many Macs I've ever owned or helped
> friends with combined. This is the peculiar bane of the 2400--but it can be
> overcome with serious persistence.
----------
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