OT: Is This RF Or Power?

[George]

Comprehension level of a Shrub critic.

[Robert Bonomi]

*IF* and _only_ if you buy one of the high-priced "full-time" UPS systems. The typical 'hobbiest'/'small office' UPS is a "standby" system - the battery power kicks in only if the line power fails _completely_.

[Tom Watson]

Good point. An interesting observation is that all of the guys who are on CRT's in offices that share the wall with the metal fabricator's shop have "jumping screen".

The guys who are on laptops, in the same offices, do not have the problem.

The guys on the other side of the hall from the offices that share the fabricator's wall, do not have the problem. The problem seems to be specific to CRT's and seems to be related to proximity to the wall shared with the fabricator's shop.

The good news is that our company is building new offices and I have my name in to get one as far away as possible from the metal fabricator's space.

Thanks for the help.

Thomas J. Watson-Cabinetmaker (ret) Real Email is: tjwatson1ATcomcastDOTnet Website:

[Robert Bonomi]

Given all that, the _real_ test is to temporarily run an extension cord from the _same_ outlet that one of the machines "on the other side of the hall", uses over to where -your- machine is. And see if _your_ screen still jumps when your neighbor's do.

Laptop LED/LCD/whatever displays are radically different in design than CRD displays, and are not subject to the same kinds of ideosyncratic behavior on -voltage- irregularities. Laptops essentially run off their batteries _all_ the time, with the line cord functioning as a battery charger. In effect, they're on a "full-time" UPS.

The machines across the hall could be on a different phase of the power distribution into the building. And the 'sag' is specific to the phase the machines 'next to the wall' are powered from.

If you can describe "exactly what it looks like" _when_ the 'screen jump' occurs, I may be able to provide better guesses. Does the picture pull in from the sides, so you see black at the right/left edges. possibly pulling in more in the middle, than at top/bottom (sort-of hour-glass like) and acts like a TV with the vertical hold out, probably "rolling" from the top down?

Or does the picture get 'twisted', and colors go "funny", with what _should_ be the same color showing as different colors at different parts of the screen? If you pull up something that makes the entire screen pure white, do you notice that the white is not the 'same shade of white' at all parts of the screen. i.e.,ill-defined areas of pale pastel colors?

The former is symptomatic of power problems.

The latter is symptomatic of magnetic impulse problems.

RFI (Radio Frequency Interference) typically shows up as an imposed 'pattern' on blocks of solid colors (herringbone/moire type stuff), and 'fuzzy' edges to things that should be sharp. Sometimes noticed as 'jitter' in a _horizontal_ direction.

[Jeffrey Thunder]

A good UPS with voltage regulation isn't that expensive. That said, one rarely if ever plugs peripherals like monitors or printers into them. Their main purpose is to save data (by not fscking up the file system on the HDD). Plugging a monitor and/or printer into the UPS will reduce the time it can power the computer while on the battery.

OBWW: I'm making a small shelf (out of wood) for a little DVD player in my daughter's room. I'm worried about stray electrical/magnetic fields harming the finish, and the Flexner book (Bible, O'Deen) says nothing about how shellac can protect against this. Would lining the shelf with lead be the best option?

[Bridger]

the problem with this is that over time the lead will become radioactive, posing a threat to your daughter's health. Sure, it might take 10,000 years to reach a measureable level, but why take chances?

[Juergen Hannappel]

No. Lead is not a good conductor, neither for electrical current nor for magnetic flux. You *could* use magneticaly soft iron, but if you do not build a complete cage it does not do anything useful.

Why should the lead do so? From cosmics?