Dim light bulb tester (UK)
I’ve just changed all my electrolytic capacitors in my power amp and got myself a Variac and Dim Light bulb tester (100W bulb).
I’m monitoring the B+ and as I increase the voltage the lamp begins to glow at about 115 volts on the Variac. I took my KT120 out leaving the other valves in (including PL519 voltage regulator tubes). I now go up to 140 volts on the Variac and the bulb begins to glow. The voltage reference tubes (regulator circuit) light up but not the one for the negative bias (which normally illuminated straight away under normal power up-but maybe not enough voltage to strike yet). So now I’m worried about stepping up the voltage anymore even though there’s no funny sounds or smells etc. I can’t believe anything is wrong as I’ve checked the capacitors so many times but don’t feel I can push it any further. Any help or experience in this much appreciated.
I mainly use a dim bulb on the first initial power on just to make sure there are no short circuits. Once I get past that initial testing phase, I take it out of the circuit. As you have found, it severely limits the current.
All up and running now, thanks 👍
Just connected an Ammeter to the mains input and it seems the 100W bulb is limiting the current to 0.2A. Think I need another 100W bulb in parallel at least?