[Asterisk-Dev] notch / high pass filter addition to zaptel

Rich Adamson radamson at routers.com
Wed Jun 29 09:00:02 MST 2005

> On Tuesday 28 June 2005 14:59, Kelly McDonald wrote:
> > The only issue I have left is a ~60hz hum that seems to be coming from
> > the card itself (bad ps bypassing is my guess)
> If you've got 60Hz anywhere in your PC replace that power supply.  I don't 
> think I've ever run across 60Hz hum in any kind of modern switchmode power 
> supply.  It just doesn't happen.

Based on postings, it sounds more like the fxo module was bad in
such a way as to cause a significan "imbalance" of the pstn line.
Something like a resistive short from tip-to-ground. That would
definitely cause the 60hz hum.

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