4 volts seems high, should be less then a volt. Are you sure the rest of the tubes are connected - with no load the voltage will be higher then with a load.
David S.
:Hello have a generic no name radio with an 80 tube and caps.........I can get the speaker to hum so I tested for ac voltage across the power supply filter caps I replaced and I can get 4 volts ac......isnt this too much???my tube tester didnt pick up any shorts on any of these tubes
Time for a little basics. If you have no load (i.e. no tubes installed) on a power supply circuit the ripple voltage (AC) will go down. The DC voltage on an unloaded circuit will go up. The value of the ripple voltage is dependent on several things. These are the size of the filter capacitors, how much load, tube leakage and some other things. To generically come up with how much ripple is too much is a hard thing to do without knowing the circuit. You mentioned earlier that you saw sparking in the 80 tube. Either the tube is defective or there is an over load or the filter size is too big or some or all of the above. I hope this helps.
MRO