Are these things I should consider bad

[TinCanAlley]

Originally Posted by jr_tech

I can't tell much from the fuzzy picture, but I suspect that the "ground" terminal of the tripler is connected to ground only through the 500 ohm resistor and series zener diode as well as the pot and 10 ohm resistor.
Even if the 500 ohm resistor were connected *directly* to ground that would not short out the diode, as there can be a voltage drop across the resistor if current is passed through it. Do an ohms law calculation and you can determine how much current is needed to raise the voltage to the zener voltage.
jr

Here's a better picture. The red outline is the ground post for the diode and spark gap. The yellow outline is from the 500ohm resistor on tripler ground connection, other lead of the diode, other lead of the spark gap and terminal one of the brightness limiter pot. The wiper of the pot goes to base of ABL transistor and terminal two of the pot goes to ground. The green outlines are the spark gap and the diode.

The reason I'm going though all this that I am not an expert in electronics and am still learning. Until I can understand how all these connections can work when they all seem to go to ground and not one of them seems to have any connection to a power source. If I can understand where the voltage for the diode and transistor bias is coming from, it will help me greatly. Is there voltage on the ground terminal of the tripler?

[jr_tech]

Originally Posted by TinCanAlley

Is there voltage on the ground terminal of the tripler?

Must be... the designer chose a 7 watt rating for the 500 ohm resistor... that would imply that something like 0.1 amp or more (DC or average pulse) is flowing through the resistor or else the designer would have chosen a lower rated (cheaper) part. The "ground" lead of the tripler must be at least 50 volts (DC or average of higher pulses) above ground for the 7 watt rating of the resistor to make sense. Without knowing the digram of the tripler or what it is connected to, the source of the voltage is not known... but for sure the "ground" terminal of the tripler is *not* at ground potential.

jr

[TinCanAlley]

Originally Posted by jr_tech

Must be... the designer chose a 7 watt rating for the 500 ohm resistor... that would imply that something like 0.1 amp or more (DC or average pulse) is flowing through the resistor or else the designer would have chosen a lower rated (cheaper) part. The "ground" lead of the tripler must be at least 50 volts (DC or average of higher pulses) above ground for the 7 watt rating of the resistor to make sense. Without knowing the digram of the tripler or what it is connected to, the source of the voltage is not known... but for sure the "ground" terminal of the tripler is *not* at ground potential.

jr

So I can use my DMM to test for voltage at the resistor. I am doing my best to understand how all this works. Looking at the schematics I think I might understand how the zener is working. If the voltage coming off of the tripler (though the 500ohm 7w resistor) goes above 7.5V, it opens and sends the excess to ground? Does that sound right?

[jr_tech]

Originally Posted by TinCanAlley

So I can use my DMM to test for voltage at the resistor. I am doing my best to understand how all this works. Looking at the schematics I think I might understand how the zener is working. If the voltage coming off of the tripler (though the 500ohm 7w resistor) goes above 7.5V, it opens and sends the excess to ground? Does that sound right?

Yes, I think that you should be able to measure the voltage... it is likely a combination of DC and AC spikes, perhaps measure with both DC & AC scales. My Tek DMM 870 has a combination "AC+DC" range which is ideal, but I am not sure that many other meters have that function.

"Opens" is not the word that I would choose to describe the action of the Zener diode, it will *conduct* at its zener point and not allow the votage to rise above that point, unless its current ratings are exceeded, in which case it *will open* (burn out) and the voltage will likely go "sky high".
jr