AR-6 tweeter help

[AR6_Project]

Hi AKers,

I’ve posted a couple of times now about an AR-6 restoration project. I’m currently working on one speaker to see if I can get it running like new.

I’ve cleaned the pots (little corrosion anyway) and replaced the old ‘cigarette case’ style capacitor with a new film one of the same uf rating. Still no noise from the tweeter. An ohmeter across the speaker wires on the front registers a circuit but resistance of only 0.03ohms or so.

Am I missing something obvious here? I have no doubt these will sound great once restored and refoamed, but the tweeters are causing some trouble!

Couple of pics attached for reference.

Cheers

 

[r_brumett61]

Hi, .03 ohms is a dead short. Make sure when testing that one lead of the tweeter is disconnected so the meter is not reading the whole circuit. The tweeter may have to be replaced. If so both should be replaced due to the fact that exact replacements are hard to find. Look at simplyspeakers.com and google for other sites that might have tweeters that would be close.

 

[goodolpg]

I'm not sure what this means... " An ohmeter across the speaker wires on the front registers a circuit but resistance of only 0.03ohms or so.".

To test the tweeter disconnect the wires from the tweeter, then measure resistance (ohms, low setting on the meter) across the tweeter terminals.
As long as you are doing that, you can use the same procedure to check the (tweeter?) pot (round ceramic control). Measure with the control all they way down, then again with the control all the way up, you should see a change. Not sure if you can do this test with the wires connected to the control, but I think you can.

 

[CJVx]

Post pictures of the crossovers and new caps, we can check that the wiring appears correct.

 

[jure29]

Hello, it is difficult that both tweeters do not work due to a short coil problem, in these tweeters with the external wires it is easy that precisely these, on the course of the cone are interrupted: observing well perhaps with the help of a magnifying glass the two pairs of cables, you will probably see a part of them green, instead of the classic copper color, this means that the wire has broken, even partially and the oxide causes you to have those values of 0.03 ohm to the instrument.
It happened to me with an AR6 tweeter identical to yours, I unstuck the cable fixing on the cone, soldered the 2 ends where the copper was OK, re-glued the cable on the cone and as a result the tweeter is back in perfect efficiency!
I am attaching the photos, you will be able to see that the other cable also has oxidation, probably sooner or later it will also stop, when it happens, I will do the same job as the first wire!
I am attaching photos in full resolution to better see the threads with the oxide problem, in the first you see the glue before drying, the second shows you that the repair, if well done, is almost invisible.

The wire re-glued after welding


Dry glue, note the left thread with green oxide!

I hope that the problem with your tweeters is precisely the interruption of the thin wires that run on the cone

 

[AR6_Project]

Goodolpg - thanks for your comment. I’ve desoldered both ends of the tweeter wires from the crossover and tested the resistance. I get 4-5 ohms. I also saw somewhere on the forums that you can do a rough check with a AA battery across the wires and listen for a quiet pop, which I did indeed hear. Note the pot also worked as you described when measuring resistance directly to the connections on the interior of the cabinet.

jure29 - thanks for your comment, there was no evidence of corrosion however I’ve applied a little more solder to the connection between the wires and the small tweeter wires on the front to ensure clean connection.

As luck would have it my soldering iron has packed in, so I’m waiting on the new one to arrive. Having not really changed anything though I would assume that reconnecting the tweeter to the circuit would not result in it functioning. If that were the case, is there anything else I need to check?

I will of course update you once I’ve soldered it back into the circuit (and post updated pics CJVx!)

M

 

[goodolpg]

That appears to be a good reading for the tweeter, and it appears the pot is operating properly.
At this point I'd inspect the crossover, the tweeter circuit in particular. Just a possibility, there could be a break in the small lead under the black tape(?) like 29 mentioned.
Very carefully see if you can remove the black tape and see what is under it and verify it has continuity.

 

[AR6_Project]

No evidence of corrosion or a broken connection under the black tape, but as I mentioned I added a little solder to the connection to the very fine wires to ensure there’s no break there.

I’ll reconnect the tweeter when the new iron arrives and share pics of the crossover circuit. Hopefully we get a different result!

 

[goodolpg]

You said you replaced the old cap, did you use a non polar cap?

 

[zambox]

interesting to know at this point how the tweeter restoration goes any update ?