Quote:
Originally Posted by radio nut
Well I guess I do not understand one thing. I now know that the tube heater line is getting too much voltage. The diagram shows the output of the rectifier going to a 1,800 ohm res. then to the heater of the 1Lb4. That is the way this set is wired right now. Do I just need to jump up the res. to lower heater volt. or does this tell me that something else is going on?
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So inspector, are you feeling a little like Columbo right about now?
Yeah 82 volts on a 1.5 volt filament will shorten the life of a tube. Are you measuring that across the filament?
It looks like all the 1lxx tubes have their filaments in series and there is a voltage divider.
Are you seeing 125 volts at the plug? That might stress things too since the set is designed for 117 volts or so. Do you have a variac so you can back the ac line voltage off a bit?
I'm kind of a 'go-by-the-schematic' unless I'm experimenting. So my feeling is something else is going on. I would continue to trace out the circuit and see what else is different.
A next step might be to check the filament voltages for each of the tubes. But they are in series and you don't want to burn out any more filaments. So maybe from the 1800 ohm resistor side of the last 1lb4 to the 150kohm side of the first 1le3. That should be around 9 volts or so.
Maybe chime will 'chime' in with some other ideas.
When I was in tech school we had a fellow there who shorted out all the resistors on CB to increase the power.
So you may have quite a restoration ahead of you.