Guest postjob62 Posted September 15, 2005 Report Share Posted September 15, 2005 Hello,Can anyone instruct me as to the proper method (if there is one) to test drivers with a multi-meter?I have a post-1970 2ax mid that cannot be made to produce any sound no matter how the pot is manipulated. Obviously the first route is to suspect the pot, but I have tried the "cabinet face down and spray deoxit" technique many times and can still not get a peep from the mid no matter what. Guess I would have thought there should be some point on the pot adjustment that would have yielded some sound unless the driver itself was bad.I just thought it might be easier to test the driver before getting in to the pots. Can testing be done without desoldering the leads?Thanks,Ed Link to comment Share on other sites More sharing options...
Guest dogmeninreno Posted September 15, 2005 Report Share Posted September 15, 2005 >Hello,>>Can anyone instruct me as to the proper method (if there is>one) to test drivers with a multi-meter?>>I have a post-1970 2ax mid that cannot be made to produce any>sound no matter how the pot is manipulated. Obviously the>first route is to suspect the pot, but I have tried the>"cabinet face down and spray deoxit" technique many times and>can still not get a peep from the mid no matter what. Guess I>would have thought there should be some point on the pot>adjustment that would have yielded some sound unless the>driver itself was bad.>>I just thought it might be easier to test the driver before>getting in to the pots. Can testing be done without>desoldering the leads?>>Thanks,>Does the tweeter work? If so, I suggest you unsolder one of the leads to the midrange..Next get a multimeter and put it across the speaker's (midrange) terminals. You should get about 5.5-6.6 ohms at that point..If you get more or less, I would suggest replacing the midrange driver..I have several of the flat style and maybe a few of the double driver style. Good luck, Dale>Ed Link to comment Share on other sites More sharing options...
RoyC Posted September 15, 2005 Report Share Posted September 15, 2005 Hi Ed,My money is on the pots. I've seen many that were so corroded that they look like they were mounted on the bottom of a boat. Deoxit won't touch these or satisfactorily clean (from the outside) most of the dreaded old pots.You will have to open them up at some point to fix 'em...might as well get it over with.Feel free to email for assistance.Roy Link to comment Share on other sites More sharing options...
Guest dogmeninreno Posted September 15, 2005 Report Share Posted September 15, 2005 Silly thought but is the jumper installed between terminals 1 & 2 on the rear main connection of the speakers? Also does this happen on one or both speakers?? Dale Link to comment Share on other sites More sharing options...
Guest dogmeninreno Posted September 15, 2005 Report Share Posted September 15, 2005 Sorry, The post should read between terminals 2 & T..Dale Link to comment Share on other sites More sharing options...
Guest postjob62 Posted September 15, 2005 Report Share Posted September 15, 2005 Hi Dale,Yes, jumper is there. Also, in the speaker with the inop mid, the tweeter does in fact work. All drivers in the other speaker to the pair work fine. Out of six drivers, only this one is non-responsive.Ed Link to comment Share on other sites More sharing options...
dynaco_dan Posted September 15, 2005 Report Share Posted September 15, 2005 Hi thereDid you try dripping Deoxit down the pots shaft?If you saw the construction of the pot, you would see this would not be a very successful application of Deoxit.If you sprayed Deoxit into the side of the pot from the woofer enclosure opening you would have much better success, and more work of course.I would be concerned if you let too much run into the rear of the pot if it should drip onto the rear of the woofers cone material.Yes there is insulation to absorb it, but. Good luck.>Hi Dale,>>Yes, jumper is there. Also, in the speaker with the inop mid,>the tweeter does in fact work. All drivers in the other>speaker to the pair work fine. Out of six drivers, only this>one is non-responsive.>>Ed Link to comment Share on other sites More sharing options...
tysontom Posted September 16, 2005 Report Share Posted September 16, 2005 >Hello,>>Can anyone instruct me as to the proper method (if there is>one) to test drivers with a multi-meter?>>I have a post-1970 2ax mid that cannot be made to produce any>sound no matter how the pot is manipulated. Obviously the>first route is to suspect the pot, but I have tried the>"cabinet face down and spray deoxit" technique many times and>can still not get a peep from the mid no matter what. Guess I>would have thought there should be some point on the pot>adjustment that would have yielded some sound unless the>driver itself was bad.>>I just thought it might be easier to test the driver before>getting in to the pots. Can testing be done without>desoldering the leads?>You can test the midrange driver without removing or unsoldering the leads. You will have to unscrew the four machine screws holding it to the cabinet, and remove the driver far enough to get the leads of a test battery (a "D" Cell is best, with wire-leads soldered on each terminal of the battery) to make contact with both soldered connections on the underside of the 3-1/2-inch driver. Hold one lead in place, and touch and release the other lead, and there should be a very discernable "crackling" sound from the driver. This does not tell you what shape its in; but if it works at all, it's probably okay. Chances are better-than-not that the level control is badly oxidized, and a "good" spot cannot easily be found by moving the control back and forth (strangely, after unsuccessfully twiddling a control back and forth, you can return to the speaker later on and suddenly locate a "live" spot). As others have said, you may as well jump in and remove the control, clean it and replace it. It is dreaded, tedious work, but rewarding. Do not change it with any other type control; use only the Aetna-Pollock control that was installed originally.Let us know if you need help in the dissassembly.--Tom Tyson Link to comment Share on other sites More sharing options...
RoyC Posted September 16, 2005 Report Share Posted September 16, 2005 Ed,If the mid is OK, here are a couple of pot photos to get you started.Roy Link to comment Share on other sites More sharing options...
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