I hooked up the old AR- LST speakers and notice the high frequency drivers are not working. Pulled the back panel with the crossover and started looking around. There is a 6uf cap that goes to the high freq. I bypassed that and still no luck. Any recommendations how I should trace the problem down?

Thanks for the suggestion S Clark. I have taken the speaker wires from the amp and put them on one of the tweeters and they all work when connected directly to the tweeters. I would think by bypassing the 6uf 50v cap I would have sound. Granted the caps are out of spec but I don't think this is where my problem is. I just don't know where to go from here.

Thanks. While looking for new caps I do not see 6uf 50 volt. I do see 6uf 400 volt. Would these be compatible? Does voltage matter as long as they are a higher value?

Thanks. While looking for new caps I do not see 6uf 50 volt. I do see 6uf 400 volt. Would these be compatible? Does voltage matter as long as they are a higher value?

volts doesnt matter as long as it is same or higher

Yes higher volts means it can work even in higher power systems,compatible yes (value the same)

cheers 

Don't the LSTs have a tweeter level control? If so, that is where your problem is.

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After looking at that mess of a crossover, wow... I don't know what I'd do.  Probably take it to one the pros and have them redesign the crossover, or bypass stuff until it plays and then sell it.

Ok, then you need to find the break.  Is the speaker dead regardless of which position the autotransformer is set to?  Can you measure continuity from the positive binding post through to where it connects to the 6uF cap? If so, move the 6 position switch to see of all the coils in the transformer are passing current. If the short is in that transformer, then I've got to hand this off to someone above my pay grade.