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Re: Classic 20 Power Transformer Dies

3/19/2006 7:56 AM
R.G.	Re: Classic 20 Power Transformer Dies Dead power transformer without blown primary fuses is very often a short on the filament winding. With the huge step down from 120 or 240 to 6.3V, the filament winding does not pull much primary current even if the secondary is shorted, because the leakage inductance and primary resistance keep things in bounds. However, the 6.3V secondary sits there and cooks until the heat melts insulation, and then you have a dead PT. Check for a heater short, and put a fuse in the heater winding before you put the next PT in.

3/19/2006 7:56 AM

R.G.

Re: Classic 20 Power Transformer Dies

Dead power transformer without blown primary fuses is very often a short on the filament winding.

With the huge step down from 120 or 240 to 6.3V, the filament winding does not pull much primary current even if the secondary is shorted, because the leakage inductance and primary resistance keep things in bounds. However, the 6.3V secondary sits there and cooks until the heat melts insulation, and then you have a dead PT.

Check for a heater short, and put a fuse in the heater winding before you put the next PT in.