Re: Case fans



Whoa--that's a big leap, fella! A shaded-pole AC motor puts out a 120 Hz magnetic field (peaks on each half-cycle). Scarcely RF--and actually well-contained within the field windings, with no sharp commutation transients.

Magnetic, perhaps, but not RF.


DC motors must commutate somehow to produce a torque. Whether with brushes or using sensors, there are sharp transients, which produce substantially more RF than any AC shaded-pole motor.

Back when the first 5.25" floppy drives were just coming...

Re: Case fans



What sort of EMI and what are the practical consequences? No one uses CRT monitors or floppies anymore and hard drives are pretty much impervious to the field generated by a small fan.

Unlike a DC fan, the AC fan isn't putting noise onto your DC lines. The original 5150 used an AC fan in the PSU.

Just curious if you have some hard data for your statement....

Re: Case fans

If you want to go completely off the beaten path, consider an AC (line powered) fan. Rotrons are still made and will probably last forever.

A bit noisier than the usual DC fan.

Re: Why do fluorescent Bulbs (CFL) last only a few months?

There was a blog article in one of the EE trade rags (Electronic Design, EDN, EETimes?) not too long ago about this subject.

One of the things that's often overlooked is that most consumer-grade CFL units are made to be burned [b]base-down[/b]. The electronics produce quite a bit of heat and burning in the inverted position just aggravates matters. Burn one in an inverted recessed can fixture and things get even worse.

Duty cycle and low-temp operation, as others have mentioned, are also major...

Re: ENVISION EN9410e 19" Monitor



This is not a difficult repair. Use a good-quality temperature-controlled iron (my 35+ year old Weller WTCP has been my mainstay) and either a solder "sucker" (e.g. Soldapullt) or solder removal copper braid. If your eyes are like mine (not as sharp as they once were), a head-band type magnifier (e.g. Optivisor) is useful for this and for reading fine print otherwise.

Pay attention to the capacitor polarity; work neatly and you'll be just fine....

Re: ENVISION EN9410e 19" Monitor

I'll ditto the remarks about Mouser or Digikey. You might find a deal on Everyone's Auction Site, but run the risk of getting counterfeits. Penny-wise, pound foolish.

Jameco or JDR are also known suppliers.

Re: ENVISION EN9410e 19" Monitor

I just got one of these in with the same symptoms--about 1-2 seconds between PSU shutdown and restart.

When I looked at the PSU, this is what I found:



Note the 5 bulging caps--4 in the right foreground and one in the background. They're all 470/25 CapXon units. I replaced them with Nichicons and the unit works fine.

The odd thing is that the CapXons are on both the +12 and +5 sides of the PSU and failed nevertheless. I wonder if there's a plague of bad 470/25 CapXons out there?...