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Re: [TCML] RE: Terry Filter Problem



Yes but, the ground area has the "greatest distance" (largest number of pads). When I built my first Terry Filter, I allowed 3/4" distance from hv terminals to various components minus the obvious parallel and series strings, and I still arced across it. What stopped this was increasing distance. I've also built a small mmc on such a pad layout. Same problems occurred. I ended up using a small pin point soldering iron and removed all the unused pads around components which took care of the problem.

Scott's circuit hookup looks good. The only thing I see worrying are the numerous pad holes. My theory is that the pad holes near the grounded terminal add up to a distance that causes a substantial arc. Most of the circuit is probably working up to the ground point and that is where I think the pads are really causing problems. The grounded area is not the only burned portion of the board. Pad holes like this with a high voltage circuit is never good. I guarantee bad things will happen (been there, done that, and it's a good experience).

Take care,
Bart

Ed Phillips wrote:
Hi Scott,

Looks like the NST outputs are making their way to ground bypassing mov's and RC circuit. See all those little copper pads on the solder side of the board? Anything between RC and MOV's need to be removed. These pads are a problem. Even all those pads around the main ground terminal. Might want to turn it upside down and run it with the lights off. One thing about these filters, they do need good isolation. Also, once carbon forms, the problem gets worse.

Take care,
Bart"

Maybe, but............... Notice that the heavy burned area is next to the ground terminal and that there isn't ANY obvious arcing between the end of the WW resistor and the red [gnd] wire in the vicinity. The copper pads are clean and the insulation is normal color in the vicinity of the resistor terminal. If I read things right the red wire is ground so the burned area is near the ground lug end of what's already a ground wire.

Why use such expensive perf board, independent of the potential arcing between ground pads?

Ed
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