07-04-2019, 02:17 PM
RE in the case connecting with float being full line voltage... Good point!
I have seen two instances where 6-Vac dial, or power-on lights, popped mysteriously. Likely from a transient when connecting the ground lead of a modern 3-wire-grounded test instrument to an older 2-wire 120-V device. In each of those instances, one leg of the 6.3-V filament winding (and the lamp) were grounded to the chassis. In one case, device and test instrument were connected to a shop circuit containing a GFCI. As soon as the ground lead of new instrument touched old chassis, it popped the GFCI (and bulb!). I have found it useful to install 3-wire plug to older devices. to fix the chassis at earth; each leg of the primary power transformer is then 60-Vac from earth.
Cheers. John
I have seen two instances where 6-Vac dial, or power-on lights, popped mysteriously. Likely from a transient when connecting the ground lead of a modern 3-wire-grounded test instrument to an older 2-wire 120-V device. In each of those instances, one leg of the 6.3-V filament winding (and the lamp) were grounded to the chassis. In one case, device and test instrument were connected to a shop circuit containing a GFCI. As soon as the ground lead of new instrument touched old chassis, it popped the GFCI (and bulb!). I have found it useful to install 3-wire plug to older devices. to fix the chassis at earth; each leg of the primary power transformer is then 60-Vac from earth.
Cheers. John
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