cross over impedence wont settle

[Txgrizzly]

Guys,
i am building the Tritrix speakers and just completed the cross overs and i hooked up a tweeter to its cross over to check it and instead of the meter coming to a steady ohm reading it kept building beyond the impendence of the speaker. after the 1st one did that i rechecked the wiring and its correct per the schematic. so i checked the other xover and its doing the same thing.
so i checked with the other tweeter and now i am getting nothing like i have an open circuit. so i went back to the original tweet and its the same thing. its acting like an open. what would have caused the ohm reading to continue to climb and then when i checked it the next time i dont get anything. i am kinda confused because my multimeter should not have been able to put anything out that could have hurt the crossovers.
any help would be appreciated...thanks

[Amphiprion]

A series capacitor in the tweeter network will cause it to read as an open. I'm not familiar with the Tritrix crossover, could you post a link? If the first item is a series cap like in most tweeter crossovers then that's the problem.

It climbs the first time because the meter is applying a DC voltage to the network and trying to measure current to get a resistance measurement. The DC voltage charges up the cap, and as the cap charges the current decreases and the resistance measurement goes up. Once the cap is fully charged to the voltage the meter applies, no current flows so it reads as an open circuit. Film caps have such little leakage it's staying charged after the first time you measured it and subsequent measurements go straight to saying open circuit without having to charge it up. Connecting a resistor to the input terminals of the tweeter XO will discharge the cap and get you back to the original state where the meter will climb again when you measure.

[Txgrizzly]

Thanks a ton Mark, i thought i had blown something up (guess i wasnt trying hard enough ) very good explanation...

[Amphiprion]

I'm pretty good at explaining stuff like this. Comes with the title "Design Engineer" at an electronics R&D company One time on an electronics hobbyist forum I ran into a guy who just happened to notice the phenomenon of dielectric absorption in the electrolytic caps of his DC wall wart power supply. That was fun to explain.

In any case, polypropylene film caps are self healing, so they can take quite a lot of abuse before they go out. I've actually only killed one, and that was when I had a 3KV cap hooked up to the output of a 12KV neon sign transformer. (I knew it would blow, but I hoped to get some useful data before it did). It actually lasted about 30 seconds, got warm to the touch (a film cap got hot!) and you could see the dielectric punch-throughs on the scope where the voltage would suddenly go from a few kV to zero in a nanosecond. But yeah, that's more or less what it takes to kill them in such a short time. Robust little devices.

Can't say the same for electrolytics or tantalums.

[Txgrizzly]

HAHA.... ahhh ok whatever you just said... :E