Paul said:
Eh well, he's gotten less persuasive in later posts. I would still
look at that p/s output with a scope if I were trying to diagnose this
problem.
The explanation was intentionally dumbed down for nay-sayers who don't
even understand a relationship between that higher 5 volts and a
failing 12 volts; and who only want to argue anyway. As you may have
noticed, no sense trying to explain, for example, by that 5 volts
relates to 12 volts. It is too complex. They don't want to understand
anyway. Shotgunners already consider themselves experts - need not try
to learn something new.
Previously explained (and completely misunderstood by shotgunning
nay-sayers) is an associated increase in ripple voltage that typically
occurs as an overloaded or failing supply outputs 11.65 volts. A
trivial but completely unacceptable 300 millivolts ripple means meter
reads 11.65 volts, as voltage to computer repeatedly drops to 11.35
volts - failure. More confusing for shotgunners, this same power
supply would 'work just fine' in another system. Furthermore is how
power supplies create 5 volts and why that high 5 volts also indicates
same problem. Do I explain why to them? No. How a meter works -
simpler stuff - is too complex.
Completely ignored was a second fact - 5.12 volts. They did not
understand the significance of that number either. It requires some
basic electrical knowledge. And finally a last factor - remove two or
more disk drives and measure that voltage. Just another paragraph they
ignored so as to argue. Therefore future posts must be dumbed down -
what you might call less persuasive. I am not being persuasive for
them. They already have that masters in EE and multiple decades of
experience.
How to explain to 'computer experts' who only known how to shotgun?
Who foolishly assume 11.5 volts on a meter means voltage is above 11.4
volts? And then say meters could not find this problem? Of course the
meter did not work for them. They did not learn how electricity works
and did not learn how meters work. These posts are for the benefit of
others who would otherwise accept outright lies from shotgunning
'computer experts'.
Anything measuring below 11.7 volts is too low. If below 11.7,
4.87, or 3.23, then a power supply is probably failing. That explains
all symptoms that the Original Poster was observing. (Notice our
'computer experts' had no advice for the OP.) That is really all
'computer experts' need know since they will foolishly recommend
shotgunning anyway.
Shotgunning in any industry is how to identify the worst techs who
also like to argue rather than learn better techniques. A meter
reading below 3.23, 4.87, or 11.7 means problems - explains
intermittent failures. Using a scope would be even better. But
shotgunning computer experts usually don't know how to use a scope.
The OP is not going to buy a scope to solve his disk drive problem.
Numbers already from his $20 meter ( and the procedure that follows)
identified reasons for his disk drive failures. His number - 11.65 -
says failure. Says voltage is dipping below 11.4. But this is too
complex for those who only know by shotgunning; who don't use a meter;
who would never understand how to use a scope..