shielding

[stanlong]

I have two A1200s one has sheilding
tin plated steel I presume the other does not is this a problem. My A600 does not have it all 3 of the A500 have it. What is shieding for?
I have no idea:

[nBit7]

The shielding to to reduce the emitted Electro Magnetic (EM) radiation produced by the electronics.  EM radiation can interfere with other EM sensitive electronic devices (particularly high gain radio receivers).

At the end of the day you don't need the shielding unless the Amiga is effecting some other nearby device (such as reducing your TV or radio reception).  I would be surprised if you found the Amiga without the shield doing this (unless there is a problem with the PSU).

[orange]

its usually used for EMI (electromagnetic interference, IIRC).
you Amiga emits various frequencies. If you try to listen to radio while Amiga is on, you'll notice the noise. metal shielding acts as 'Faraday cage' to stop EMI coming in or out of it.
It also acts as plain protection and its 'earthed'

edit: bah, slow again  :roll:


BTW, I had interference problems with radio even when shielding is on.
the Faraday cage is supposed to protect you 100% only for 'static' fields, I think (unlike EM). so it only limits the EMI

[nBit7]

BTW, I had problems with interference with radio even with shielding. the Faraday cage is supposed to protect you 100% only for 'static' fields, I think (unlike EM). so it only limits the EMI

Shielding will only help with radiated emissions.  Conducted
emissions and common mode noise will radiate out of the cables and travel through the mains and into other devices.  This can be helped with ferrite beads (those lumps you see near the connector on most modern cables) and In-line filters.

Edit:
I should also point out that a Faraday cage does not protect against 'static' fields. And EM waves require a changing field (see Maxwells equations).

[darksun9210]

actually, thinking about it, my neighbour was complaining that his alarm clock radio thing was emitting lots of humming and had i got any electronics in the room that backed onto his house...

i went with "i have a few bits and pieces, but nothing major."

none of my migs have shielding, but i think i might take the time to put it back if i can fit it. plus this may resolve the moving spots on the TV i use for one of the A1200's...

[nBit7]

actually, thinking about it, my neighbour was complaining that his alarm clock radio thing was emitting lots of humming and had i got any electronics in the room that backed onto his house...

humming is sometimes the windings in the transformer moving due the changing magnetic field inherent in the transformer.  

[orange]

yes, I know EM is 'dynamic', I said *unlike* EM. and I meant electrostatic field.
but, I mixed up some things, it seems that 'full cage' would completely block dynamic too.

edit: then again maybe not completely.. wiki

[stanlong]

well i have noticed that one channel on the  TV does not get any picture or sound when using A500 with shielding  however this does not bother me cause i cant really do both
writ and watch tv.
thanks for you repies
I thought it might be a health hazard