[Hallicrafters] Discharging caps

[rrkrr]

Doug,
If you turned the radio back on after unplugging it and got sound, it 
had to be fairly quickly after unplugging it - while the tube filaments 
were still warm enough to operate.
If the on/off switch is in the primary circuit of the power transformer, 
I can't see any advantage in doing this to discharge the capacitors 
faster, as the circuits will discharge at the same rate whether the 
power switch is on or off if the radio is already unplugged.  I'm 
guessing this particular radio must have had the on/off switch ganged 
with a gain control of some sort.

If you want to be sure the radio is discharged, wait several minutes 
after you turn it off and then use insulated clip leads to ground the  
B+  through a power resistor of a few hundred ohms.  That will get the 
voltage down to safe levels in a few seconds without a big spark.  This 
assumes you're working on vacuum tube receivers.

Bob K4ERR



Douglas wrote:
> I want to be clear on this: after unplugging the
> radio, I turn it back on and leave it a lone for
> awhile. Once when I did this, one radio had a
> momentary spark of life before it went went dead,
> which makes sense that a few of the caps still had
> some juice in them. Should this be sufficient to
> discharge the caps in most of these old radios?
>
> Doug
>
> Ps. I haven't been bit yet and don't plan on it.
>
>
>  
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