Strange Problem With Monitor being around Microwave..

Thanks all. Good to hear it's not messing up anything that's all I care really...

jason

Yes, you'd think it was pretty small - but this happens all the time. It just doesn't take that much field to affect the typical CRT display. (I've seen AC fields all the way down to 0.1 Gauss or a bit less still result in visible movement on the screen, during mag. susceptibility testing - and just to put that in context, that's something like a fifth of the strength of the Earth's field typical in North America.) The problem is that it's an alternating field; low-level DC fields simply cause a static displacement, which you'll either ignore or adjust out with the centering controls, but an AC field results in a very annoying jitter.

Bob M.

It may be hard to believe, but as I noted in my other response here today, it doesn't take that much field to cause a problem for a CRT.

Unfortunately, magnetic fields are not that easily contained. Simply saying that "the whole thing is encased in steel" does NOT mean that there is zero magnetic field outside the unit.

It's certainly A likely source, but probably not the only possible source.

Bob M.

snip

Yes I know,

But this is supposedly a very small normal leakage from a standard consumer source, the microwave transformer, encased in steel located at least several feet away. I did overlook the front panel controls area on the microwave. That may have large internal openings. Still, unlikely to be the cause I believe but -- Ockham's Razor. Regards . snip

Plugged into same or adjacent AC circuit? Doubt if it is Microwave RF field; they are not supposed to leak that much if properly buttoned up even though there is several hundred watts of microwave RF floating around inside to cook/heat the food. So that means interference either magnetic field and/or distortion of the AC waveform due to the m.wave transformer saturating each half cycle (120 times a second?). Read somewhere that those m.wave mains transformers which feed voltage doubling rectifier circuits for up to 5 to 6 Kv Dc for the magnetron do operate into saturation, waveform not being important.

Excellent point: Sometimes see notices in restaurants and lunch rooms where 'customers' may microwave food themselves "Microwave in use"; as a warning to pacemaker users! Also at an airport lunch counter where microwave was in use by serving staff.

I've never believed that was more than a stupid warning, i.e. rubber ducky marked "Not a Flotation Device"!

The warning is in case the door seal becomes defective. The leaking high power RF can cause erratic operation or total failure of the electronics in their pacemaker. Microwave ovens in commercial settings get a lot of use so the chances of a failed seal are much higher.

That's exactly who the warning is for, "The stupid!" On the other hand, if you cant swim, anything that floats may improve your chances of keeping your head above water for a few more minutes but the toy maker doesn't want to be sued if you drown anyway.