> hello!.. i bought a new digital multimeter to be shure...
> it is 4.1 volts on the filament.. i will be resoldering
> everything this evning.
>
> //SM7TVJ
It is VERY unusual to have a bad connection cause 4.1 volts
without serious smoke. The reason is simple.
The tubes draw 30 amps at 5 volts. That's 5/30= .17 ohms
when fully hot
The nominal voltage at the transformer is 5.4 volts. The ESR
of the system is .4/30=.013 ohms plus .17 = .183 ohms
This means a solder joint to reduce voltage .9 volts would
have to have about .038 ohms. At that point current would be
about 24 amps, voltage at pins about 4.1 volts
The solder joint would dissipate .9*24 = 21.6 watts
How do we make a small solder joint that dissipates 21 watts
without smoking? Pure luck allowing several joints to share
the voltage drop and heat?
Maybe, but it doesn't seem likely in most cases.
Maybe someone changed something in the amplifier?
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