Champ Micro rebuild

andrewRneumann

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Mar 22, 2020
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Cincinnati, OH, USA
I'm sorry but if I look at the pic's I'm sure the orientation of the transformers changed. Look at the British flag. The long side of the flag was at 90 degrees to the long side of the OT. Now it's parallel and closer.

But I think there's help from a more knowledgeable person, so I'll follow this in silence from now on.

And the center lines are not aligned with one another… some of the worst magnetic field escapes at the corners.

I wouldn’t rule out your hypothesis completely. We’ll all learn something together as this develops.
 

Hyakuya

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Feb 10, 2021
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Brighton, UK
I think I've got enough slack in the wires to the PT to allow me to disconnect it from the chassis and twist it about a bit. At least I'll see if the hum changes.

Also think I'll disconnect the EF80 valve base from the chassis and see if I can turn that and separate it from the rectifier a bit more.

I do have a 10x probe so I'll have a play with that too though I'm not very good with the oscilloscope yet so I'm never really too sure what I'm looking at.
 

Len058

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Jan 31, 2021
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I maybe had a stupid idea. When you have some time waiting for answers or whatever. You could try to make a faraday cage with aluminium foil and maybe some cardboard. Listen if that reduces the hum when you put it over the OT
 

Paul-T

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That is part of the problem as there is a variety of opinion and some of that comes from folks obsessed with Faraday shielding for EMP pulse.

This site says aluminium is inefficient compared to ferrite metals but I don't find it particularly credible.
 
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Hyakuya

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Feb 10, 2021
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Location
Brighton, UK
Good news ...

Took out the PT today and connected it up with croc leads.... No hum. So that's good, thanks @Len058. I'm going to move the OT as the path of least resistance to fix this.

Still a faint crackling noise and I'm suspicious this may be because the EZ81 and EF80 may be too close to each other.
 




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