power packs on //, Mac
B...@psuvmb.bitnet
talking about the IIGS when he commented that the power pack on the GS was the
same as in his //e, and the same as in the //+. He also commented that he did
not need a surge protector on his //e (as I have one on my Mac +) because of
how well his power pack was built. He also maintains that above a surge of
approx. 150 volts, the Mac power source would go boom, where his would take it.
Also, that his computer would take no damage, where the Mac might.
The only experience that we have is when a friend of ours had his Mac smoke
at one of CMU's dorms, after a faulty line carried 220 volts to the computer,
taking out all electrical devices. After a check, the only damage to the Mac
was burned insulation on the incoming power line.
Finally, he maintains that the power pack in the // series is SMALLER by
components, as if you had to box it, the pack would end up bigger from the Mac.
Well, can any of the gurus of the hardware world (HELP APPLE CORP.) answer/
refute my roommate (a senior EE that I have always felt knew what he was doing)
?????????
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George A. Brownfield
Aerospace Engineering '87
The Pennsylvania State University
Bitnet: GAB @PSUECL
UUCP: {akgua,allegra,cbosgd,ihnp4}!psuvax1!psuvmb.bitnet!b5u
"We don't get laid much, but we're building the future"
-Engineering majors, according to Robin Williams
=========================================================================
Bill Mayhew
The last time I looked, I was Baron over about 14 apple ][ and //e
computers. No GS yet.
I have had a lot of trouble with the power packs in the ][ and //
versions. We have pretty good power here; it stays right about
119.5 volts with just a little rf hash from various devices around
the building. We get occasional transients from things like air
conditioner motors, but those are rarely greater than +/- 10 volts
riding on the regular a.c.
We use The apple computers for lab. data acquisition. I have
several that are used for long term monitoring of eeg signals from
rats. On these computers, the power packs usually konk out after
about 3-4 months of continuously on operation.
The failure mode is quirky. What happens is that once the power
packs are shut off and cool down, they do not want to turn on
again. When turned on again, the Apple will sit there inert for
about 10 minutes, and then suddenly the power pack will wake up and
turn on. Some times the computer will crash a couple of times in
the first few minutes as the power pack "flickers".
I think if you peek in the back room of your friendly neighborhood
Apple dealer, you are likely to see a pretty high stack of gold and
/ or silver dead Astec power supplies!
Note that we haven't been over-taxing our Apples. Generally they
have a Moutain A/D-D/A, 16K card, and disk drive(s). The drives
are used only infrequently as the data comes in.
I've done post mortems on a couple of the fried-out supplies.
Generally, I'd say that trying to repair one that has failed as
above isn't worth your time, as multiple components degrade with
age. The high-voltage energy storage capacitors get leaky, the
switching transistor degrades, and in one case the RF transformer
shorted out.
Lately, I've started using third party power packs. If memory
serves me right, the one from Jameco is pretty good. It also has
vent holes to allow air to circulate inside the power pack to keep
the temperature down, which should improve the life of the
capacitors. Be ware of the cheap replacements: you get what you
pay for!
As far as using surge protectors goes, it's probably not necessary
with the Apple ][ and // (and presumably the GS) uless you've got a
really serious power problem. If your power is really that bad,
you'll have to get a really good power conditioner to clean it up!
We don't have any McIntoshes here so I can't comment directly.
There is no reason to believe that the Mac power unit is a vastly
different technology from the ][. The Mac is likely to be more
reliable as air can more easily circulate through the supply!
Component count rarely says very much about the reliability of a
power supply; the quality of the design engineering matters more.
Given the per-part reliability is equivalent, something with more
parts is more likely to fail in a statisitical sense; this ignores
the overall sensibility of design, though.
One last word about surge protectors. Most of the cheap ones I've
seen don't really protect your computer. You'd be better off
unplugging your computer when it is not in use, and buying a couple
of boxes of diskettes instead.
Bill
Bill Mayhew
Division of Basic Medical Sciences
Northeastern Ohio Universities' College of Medicine
Rootstown, OH 44272 USA phone: 216-325-2511
(w...@neoucom.UUCP or ...!cbatt!neoucom!wtm , etc.)
Loran N. Yourk
>
> Lately, I've started using third party power packs. If memory
> serves me right, the one from Jameco is pretty good. It also has
> vent holes to allow air to circulate inside the power pack to keep
> the temperature down, which should improve the life of the
> capacitors. Be ware of the cheap replacements: you get what you
> pay for!
>
Applied Engineering also sells a power supply for the ][+ & //e
computers. It is suppose to be better designed and extra heavy
duty. Some of the problems people were having with AE's speed up
card was directly related to the week power supply of the Apple
computers.
................................
>
> One last word about surge protectors. Most of the cheap ones I've
> seen don't really protect your computer. You'd be better off
> unplugging your computer when it is not in use, and buying a couple
> of boxes of diskettes instead.
>
................................
I have seen two computers which were on in a lab, one with a Name
brand system saver and the other without any surge protector.
They were used for unattended data acquisition so they were often
on during thunder storms. During one particular storm the power
line they were plugged into took a lightning hit. The computer
without any protection had to have the mother board replaced as
well as a couple of cards. The one with the system saver had to
have the system saver replaced and that was all. No one can
really say that it was the system saver that saved the computer
of if it was just the randomness of lightning but the extra
$100.00 (actually less than that) seems worth it to me.
................................
> Bill
>
> Bill Mayhew
> Division of Basic Medical Sciences
> Northeastern Ohio Universities' College of Medicine
> Rootstown, OH 44272 USA phone: 216-325-2511
> (w...@neoucom.UUCP or ...!cbatt!neoucom!wtm , etc.)
................................
Loran Yourk
ihnp4!ihlpf!lyourk
Bill Mayhew
Loran points out in the previous article that the System Saver
might have actually saved one of two apples that were plugged into
the same brach circuit taking a lightning strike.
The thing that Loran points out is that the System Saver that he
used is a $100 decently constructed device. That is the point that
I was tring to make. If you buy a protector, you really sould
spend the money to get a good one. The ones that go for $19.95
genrally don't do any good at all. Even the $$$ protectors are
not completely infallable. The only sure thing is to unplug the
computer during dangerous times (i.e. storms).
Also both the Mac and Apple ][ can be cooked by unexpected
connection to 240 volt power. You should always check an outlet
with a voltmeter before plugging in your computer in an unfamiliar
location! Some of the older Apple ][s had a switch behind a small
plastic cover just above the linecord connector. The cover could
be removed and the switch changed to 240 volts. Other apples had a
jumper wire for 240 volts inconveniently located inside the
riveted-shut power pack.
Bill
John Mulhern
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John Mulhern
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