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Author Topic: I think my Amiga (and modem?) is hyper-sensitive to E/M noise! What to do?  (Read 1912 times)

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Offline AmigaManceTopic starter

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  Hi.
 I think my Amiga 1200 is ultra sensitive to external electromagnetic noise! Here is why:

 Symptom 1: If i switch the room fan ON and OFF a few times, while i write something to my HD, the whole system _WILL_ hang with the HD led being permanently ON. WTH! :nervous:
 This can also happen with the room light, but more rarely.
 What can i do about this? Except of placing the fan away from my Amiga or... not touch switches while my HD is working? :-(
 If it matters, the fan is located more closely to my Amiga (desctop) than to my HDs which are hosted to a pc tower.
 Also, the E/M shield of my Amiga has been removed, but i think its purpose is to reduce the emission of E/M radiation FROM the Amiga, not to protect it from external one. Or am i wrong about this?


 Symptom 2: If i turn the room fan ON or OFF while i download something my modem stops for half second and then continues to download again. Same thing happens with the room light.
 If i flick the light/fan switch quickly, the modem will disconnect.. It will also disconnect when certain types of motorbikes are passing across the street. :roll:
 I don't know if i should attribute this to the phone cable, modem, serial port (silversurfer) or to my Amiga itself. So perhaps we should focus at the first symptom which is more worrying anyway.
A1200 PPC user.
 

Offline AmigaManceTopic starter

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Re: I think my Amiga (and modem?) is hyper-sensitive to E/M noise! What to do?
« Reply #1 on: September 18, 2007, 02:52:22 PM »
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did you tried to plug both things in another power plug each? maybe its some power spike transferred thru power cables and not thru air

 Yes, i have plugged then fan and the PSU in the same plug, thus what you suggested sounds logical. An electrical negative spike instead of an E/M pulse. So, i decided to experiment a little with it:

a) Kept the fan at its original place (near the desctop) but plug it in a different plug: (which is located in the same room though. i don't now how much it matters) No results. The HD hangs after a few switch clicks. :-(

b) Re-plug the fan where it was but move it about 2 meters away from the Amiga. No results either. :-(

 Atm, it seems like an E/M thing, IMHO, but to be sure i will plug an extension cable, move the fan to another room and fire it up from there. That should exclude it or confirm it...



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As for the interference from motorbikes, that's usually down to the metal supressor casing being removed from the sparkplug caps (to reduce electrical shorts in wet weather)

 Yep.

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although I'd have thought that this type of interference would only affect aerial/satellite based reception/transmission. Perhaps someone more knowledgeable can shed more light on that issue.

 Well, i can't exclude a coincidence but i think it affects my connection. The modem either disconnects or lowers the connection speed.

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It could just be that you've got some dodgy cable shielding.

 Although the HD problem is what bugs me right now, how can i tell if the phone cable is shielded in the first place? It looks like a very simple one.
A1200 PPC user.