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Old 11th Aug 2017, 7:40 pm   #1
McMurdo's Avatar
Join Date: Jun 2009
Location: Staffordshire Moorlands, UK.
Posts: 3,252
Default Toroidal choke failure

I've just spent a couple of days fault-finding on a class-D audio amplifier and found the fault to be the output choke gone short. The choke, wound on a small (2 coin size) ferrite toroid has rather thick ECW (18swg) and 40 turns. It's very tightly wound to get it on there, and adjacent turns have bitten through the enamel and reduced the inductance to nothing.

My question, for you coil winder experts (!) is, when I come to hand wind my replacement, is there any way of avoiding a similar failure? It's rather stiff wire going around some tight corners and over itself...this is where its shorted. It hasn't failed in any way due to heat or corrosion.

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