wrote in message
...
On Sunday, November 10, 2013 2:14:41 PM UTC-5, Flasherly wrote:
I then wrapped the PS with tin-foil, ostensibly, to determine I'd
stopped spurious RF propagation from (somehow) entering the tape
during backup processes. Nevertheless, the problem was solved by a
tinfoil-wrapped PSU.

If RF radiation caused a tape drive problem, that tape drive was defective
by design. If a PSU was radiating that much RF, then that PSU was defective
by design.

Today's power supplies are not necessarily better than what powered 8080
based computers (before PCs). For example, the original IBM PC featured a
'Power Good' signal so that corrupting execution would not happen with
defective power.

I recently bought a used supply. Opened it. Discovered missing and
required filters. Holes for those part existed. Jumpers were installed so
that the manufacturer could cut costs by 'forgetting' required parts. Then
I noticed other missing circuits. So I continued the investigation.

Power Good signal for this recently built computer did not monitor
voltages. 12 and 3.3 volts could be missing. Five volts could have been
only three volts. And that Power Good signal would report all voltages OK.
A major fubar existed because so many computer techs do not even know basic
PSU functions.

This 'defective by design' supply - promoted as an ATX supply - could
explain why power loss corrupts data and other problems. An example of PSUs
marketed to computer assemblers who 'feel' they are computer savvy rather
than learn what a PSU does.

How many 'know' unexpected power loss is destructive? Many saw a sudden
power loss create other failures. Then assume power loss is destructive -
using observation or hearsay as fact. Unexpected power loss never causes
damage to properly designed equipment - not even disk drives. But many just
know because they saw damage. Or learned from hearsay. Assumed a conclusion
based upon observation.

If enclosing a PSU in tin foil eliminates failure, then a 'symptom' is
defined; not a solution. First find symptoms - especially those that are
reproducible. Solutions come later after identifying a reason for that
symptom. A defectively designed PSU? A defectively manufactured tape
drive? Tin foil did not cure a problem; only cured a symptom. Since a PSU
must not output major RF. And tape drives must make RF radiation
irrelevant.

Our current PSU standards are roundly superior to what existed before the
IBM PC. And still many consumers buy PSUs that are inferior to old
technology. A computer assembler (not the PSU manufacturer) is responsible
for what is inside a computer's PSU. Many computer assemblers do not even
know that.

Properly designed PSUs are not damaged by the load. An overheated PSU
must not cause computer damage. And would not cause a destructive surge.
Early posters noted this. And also recommended a tool that every informed
computer troubleshooter uses - a meter. So that problems are identified
(with numbers) before fixing anything.

A PSU damaged by its motherboard would be as defective as that PSU with a
bad Power Good signal.

+ A lot. Well said
Chris