Sparky Dave:mapj1:
looking at the photo of that open lead, I think we have to imagine the chip 'doing the splits' between two things at not quite the same voltage, both nominally earthed at the mains socket, but via quite a large loop of cables that gives some inductance and a time delay to the two paths and a fast spike may get round one way or the other such that there is a short duration large voltage difference at the chip.
It is the sort of design that keeps EMC consultants in business, no series chokes, no clear marshalling of the screens, no overall screening can - lines from the chip direct to touchable pins, with no obvious series current limiting choke or ESD trapping - false economy all round..
The two fixes are to either reduce the area of the pick up loop, (shorter fatter leads or an over braid on the lead between PC and monitor), and/or better to stop the spikes getting in there in the first place - which may or may not be mains borne - the swap-over test will tell..
Mike
We've just had the monitor go off so swapping the phase has not worked. Just can't get my head around this at the minute as the more I look at it the less it makes any sense! Definitely missing something here!
People who have had the same leads from the old office set up, and just moved them to their new set up have had the same issues as people who have had new leads. People with the same monitors and PC's as before they moved, all having these issues, people on different phases! Rings tested off ok (R1R2 and ins res) lamps switching monitors off, even when on different phases to one another, Scope's showing crazy readings, deviations on the phase waveform, and the noise on the monitors themselves etc etc.. either someone has given me false info on the leads and they are all faulty / temperamental or there's something very very bizarre going on. I've tried so many different leads though.
It's just a normal office set up mirrored exactly the same on both sides and shouldn't really need any special leads for monitors as far as I can tell.
I understand that scope could lead me on a wild goose chase but the reaction to the lamp on the problem side of the room is very real and you do see the difference on the scope.
I'm going to do an earth loop impedance test tomorrow and then after that i'm going to go back in time 24 years, and continue with my carpentry and joinery because I never had a stair case just stop working all of a sudden!
Oh, and there's someone in the purchasing dept claiming that her monitor keeps going off and that she has replaced leads too .... her sockets are fed from DB8 (our problem ring is from DB8) and it's an old PC station that someone used before she moved up there without any issue!..... Maybe she has bad leads too I don't know anymore!
Sorry, the dirty ring is from DB5
Sparky Dave:mapj1:
looking at the photo of that open lead, I think we have to imagine the chip 'doing the splits' between two things at not quite the same voltage, both nominally earthed at the mains socket, but via quite a large loop of cables that gives some inductance and a time delay to the two paths and a fast spike may get round one way or the other such that there is a short duration large voltage difference at the chip.
It is the sort of design that keeps EMC consultants in business, no series chokes, no clear marshalling of the screens, no overall screening can - lines from the chip direct to touchable pins, with no obvious series current limiting choke or ESD trapping - false economy all round..
The two fixes are to either reduce the area of the pick up loop, (shorter fatter leads or an over braid on the lead between PC and monitor), and/or better to stop the spikes getting in there in the first place - which may or may not be mains borne - the swap-over test will tell..
Mike
We've just had the monitor go off so swapping the phase has not worked. Just can't get my head around this at the minute as the more I look at it the less it makes any sense! Definitely missing something here!
People who have had the same leads from the old office set up, and just moved them to their new set up have had the same issues as people who have had new leads. People with the same monitors and PC's as before they moved, all having these issues, people on different phases! Rings tested off ok (R1R2 and ins res) lamps switching monitors off, even when on different phases to one another, Scope's showing crazy readings, deviations on the phase waveform, and the noise on the monitors themselves etc etc.. either someone has given me false info on the leads and they are all faulty / temperamental or there's something very very bizarre going on. I've tried so many different leads though.
It's just a normal office set up mirrored exactly the same on both sides and shouldn't really need any special leads for monitors as far as I can tell.
I understand that scope could lead me on a wild goose chase but the reaction to the lamp on the problem side of the room is very real and you do see the difference on the scope.
I'm going to do an earth loop impedance test tomorrow and then after that i'm going to go back in time 24 years, and continue with my carpentry and joinery because I never had a stair case just stop working all of a sudden!
Oh, and there's someone in the purchasing dept claiming that her monitor keeps going off and that she has replaced leads too .... her sockets are fed from DB8 (our problem ring is from DB8) and it's an old PC station that someone used before she moved up there without any issue!..... Maybe she has bad leads too I don't know anymore!
Sorry, the dirty ring is from DB5
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