On Jul 18, 10:18 pm, "Michael A. Terrell"
wrote:
He took a real beating on news:alt.certification.a-plus a while
back. He kept bleating about a long gone standards group for business
equipment, and claiming that all personal computers had to boot and
continue to work at 90 VAC input. I posted a long list of power supply
model numbers and the nameplate specifications, which he dismissed as
irrelevant, because I didn't have a degree, like him.

w_tom saw repeated accusations provided without technical facts.
Technical facts were presented - and ignored by technicians who
somehow knew without even first learning industry standards.
Demonstrated here and again is why Michael Terrell *knew* computers
must not work at 90 VAC. He completely ignored industry standard
numbers. He did not understand that faceplate numbers are often
derated numbers. He chose to believe derated numbers rather that
industry design standards.

Many computer power supplies that must operate even at 90 VAC will
not say 90 on its faceplate. But industry standards define reality.
Technicians would not know what reality is - unless the technician
learned (instead) from industry standards.

According to Michael Terrell, a faceplate number is biblical?
That's what we sometimes tell technicians when they have trouble
grasping concepts. Computer power supply typically exceeds those
numbers. Again consult Intel specs - what Michael repeatedly ignored
because those standards contradicted them. Computers under maximum
load must start up even when voltages are only at 90 VAC. Exact quote
(again) from those Intel specs is:
The power supply shall be capable of supplying full rated output
power over two input voltage ranges rated 100-127 VAC and
200-240 VAC RMS nominal. ... The power supply must be able
to start up under peak loading at 90 VAC.

From Table 1
Minimum 90 Nominal 115 Maximum 135 VAC RMS
Minimum 180 Nominal 240 Maximum 265 VAC RMS

Quoted directly from standards that ATX power supplies must meet.
Still Michael Terrell denied those numbers as he also denies how surge
protectors do and do not work.

This is not about power supplies. This is about the many who somehow
know without even learning basic technology - ignore standards. These
same people promote plug-in protectors as some kind of magic box
rather than learn the technology. Demonstrated again is what also
happened in alt.certification.a-plus . Technicians repeatedly denied
facts and numbers.

Another standard for electronics is from the Computer Equipment
Manufacturers Association. Numbers from that standard also contradict
Michael Terrell:
Undervoltages without interruption-
50 volts RMS for less than 20 msec
85 volts RMS for less than 0.5 sec
95 volts RMS for less than 10 sec

Another poster in alt.certification.a-plus stated what reality
really is - directly contradicting Michael Terrell both then and now:
Tom MacIntyre in "Motheboard Problem? Post Problem?" in
alt.certification.a-plus on 7 Sept 2001
We operate everything on an isolated variac, which means that I can
control the voltage going into the unit I am working on from about 150
volts down to zero. This enables us to verify power regulation for over
and under-voltage situations. A linear supply (many TV's) will start to
lose its regulation from 100 volts down to maybe 90, and the set will
shut off by 75 volts AC or so.

Switching supplies (more and more TV's, and all monitors I've ever
seen), on the other hand, are different. Although it's hard on the
primary section due to the current and duty cycle of the switching,
they can and will regulate with very low voltages on the AC line in;
the best I've seen was a TV which didn't die until I turned the variac
down to 37 VAC! A brownout wouldn't have even affected the
picture on that set.

How did a TV work at 75 volts when its faceplate says otherwise?
Michael - the faceplate is a derated number - repeated because you
still have problems grasping it. You are supposed to know that just
like you are supposed to know what a protector does, what destructive
surges seek, and why effective protectors have that dedicated earthing
wire.

How many times was Michael Terrell contradicted with technical facts
and numbers from reality ... again? Three? Four? It could be 100.
History suggests he will still deny the 90 VAC spec number. Quoted
from an industry standard - and he will still deny it?

Those who promote Panamax products as effective protectors, well,
why does the manufacturer's numerical specification forget to make
that same claim? Panamax has no dedicated earth ground and therefore
does not claim to protect from that type of surge. If it does not
mention various types of surges, then maybe some techs will assume all
surges are same type? That is how Panamax, APC, Monster Cable, and
the grocery store protector are all recommended. Half truths that
ignore basic technology. But again, why look at numbers when one knows
by even denying direct quotes from an Intel spec.

Only beating in that previous discussion was truth and reality. So
many accusations made by denying technical facts and ignoring industry
standards. Why did Michael Terrell deny those industry standards?
He did not even know that faceplate numbers may be derated. He should
have known that reality before posting. He also should have learned
what shunt mode protectors do before promoting myths. No earth ground
means no effective protection.