dynaco_dan

>>>Hi there >>> >>>Another 2 1/2 cents worth from me now. >>> >>>Have you tried, Acetone, which is similar to lacquer >>thinners, >>>for softening the spider glue? >>> >>>That is all I've ever seen used up here. >>> >>>All safety procedures must be followed, read the safety >>>haszard sheet, this stuff is not for inhaling. >>> >>>I have seen a spider come off in about 30 seconds once the >>>glue is dampened. >>> >>>Just use a 1/2" wide paint brush to apply it. >>> >>>Good luck. >> >>Vern, >> >>I haven't tried acetone on the AR parts, but it's probably a >>great chemical to use. Ironically, I use acetone and >lacquer >>thinner on a pretty regular basis on other projects, but >I've >>never tried them on the AR speaker glues! I think I was >>surmising that acetone would damage urethane-foam materials; >>but after all, there is no surround to dissolve at this >point! >> Both acetone and lacquer thinner are very volatile and >>flammable, so you have to be very careful with them. >> >>Thanks for the suggestion! >> >>--Tom Tyson > > >Hi again. > >Lacquer thinner wasn't used, but Acetone is still being used >here locally. > >If I remember correctly, Acetone, is considerably more >dangerous than Lacquer thinners. > >Sorry, I didn't expand upon this more thoroughly, previously. > >I must repeat that, "you should," "rather, "must read," the >health haszard sheet on the internet. > >Also read the containers caution label very carefully and >abide by their recommendations. > >Acetone is, as Tom points out, very flammable, but more >importantly, it's not to be inhaled under any circumstances. > >It has an effect on the lungs, and probably the brain as well. >DUH. > >It should be used either outdoors or in a well ventilated and >exhausted cabinet or room. > >As Tom mentions, use caution when contacting materials, if it >should be something like a new surround, it will disolve it >real quick, there is no time even for oops. > >I have watched a local speaker repairman, from a distance mind >you, use it for over 10 years. > >Thanks again Tom for your feedback. > >Good luck and do be careful. > Hi again; I always remember something else to rattle about after I've walked away from my computer. Duh. I am sure most of you wouldn't use acid swabs or synthetic bristled brushes for the Acetone. I believe that the acid swabs are synthetic material. I, forgot to suggest a natural hair type paint brush, otherwise I think you would dip the brush into the can of Acetone, and find you wouldn't have any synthetic bristles left. Reminds me of a time I was hunting and wanted to put gas from a non-funneled gas can into my gas tank. I used a sterifoam cup. Ok, only this one time. Well, the cup did fill up once, just before the bottom and the rest of it disolved. Duh. Canadian genius at work here. NOT. Live and learn.

>>Hi there >> >>Another 2 1/2 cents worth from me now. >> >>Have you tried, Acetone, which is similar to lacquer >thinners, >>for softening the spider glue? >> >>That is all I've ever seen used up here. >> >>All safety procedures must be followed, read the safety >>haszard sheet, this stuff is not for inhaling. >> >>I have seen a spider come off in about 30 seconds once the >>glue is dampened. >> >>Just use a 1/2" wide paint brush to apply it. >> >>Good luck. > >Vern, > >I haven't tried acetone on the AR parts, but it's probably a >great chemical to use. Ironically, I use acetone and lacquer >thinner on a pretty regular basis on other projects, but I've >never tried them on the AR speaker glues! I think I was >surmising that acetone would damage urethane-foam materials; >but after all, there is no surround to dissolve at this point! > Both acetone and lacquer thinner are very volatile and >flammable, so you have to be very careful with them. > >Thanks for the suggestion! > >--Tom Tyson Hi again. Lacquer thinner wasn't used, but Acetone is still being used here locally. If I remember correctly, Acetone, is considerably more dangerous than Lacquer thinners. Sorry, I didn't expand upon this more thoroughly, previously. I must repeat that, "you should," "rather, "must read," the health haszard sheet on the internet. Also read the containers caution label very carefully and abide by their recommendations. Acetone is, as Tom points out, very flammable, but more importantly, it's not to be inhaled under any circumstances. It has an effect on the lungs, and probably the brain as well. DUH. It should be used either outdoors or in a well ventilated and exhausted cabinet or room. As Tom mentions, use caution when contacting materials, if it should be something like a new surround, it will disolve it real quick, there is no time even for oops. I have watched a local speaker repairman, from a distance mind you, use it for over 10 years. Thanks again Tom for your feedback. Good luck and do be careful.

>>>It appears that the late-70s designation of the >200003/1210003 woofer (AR-9/AR-11B) you show is consistent the >advent of the aluminum voice-coil former.<< > >Tom, I believe you are right about when AR changed from Nomex >to Aluminum voice coil formers. When AR changed the ADD line >from what we on the forum have referred to as "A" model ADD >speakers -- Brass logos, White/yellow fabric on tweeter, black >screen on midrange... The 200003 woofer was the same as that >used in the AR-3a and AR-LST -- Black flange, wide masonite >ring, hex screws... > >I have my Dad's AR-11 "A's" here with me. I just pryed up a >small portion of one woofer dust cap (a replacement porous >dustcap installed by a shop he had refoam the woofer for him, >it isn't glued down very well) -- > Nomex VC former, just like the AR-LST woofers I refoamed a >few years back. > >All the AR-11 "B", and AR-9 200003 woofers I've refoamed are >the silver flange version -- all have Aluminum VC formers. >Pretty good indication this is when the change from Nomex to >Aluminum was made. > >>>One way to help in removing the glue on the woofer flange is >to use denatured alcohol to soften the glue, and then >carefully scrape away.<< > >Just to add my techniques -- > I've used "Goof Off" and Isopropyl alcohol to loosen the >glue. The alcohol works better than the Goof Off. I use Q-Tips >saturated with alcohol to "scrape" the foam remnants away >before going after the glue. > >The best tools for scraping the glue from the masonite ring >and the outer edge of the cone are razor type knifes -- >X-acto, Stanley retractable blade knife, Box cutter/Wallpaper >razor knife with break-off blades. Whatever type knife you >use, use the BACK OF THE BLADE (not the sharp edge) to scrape. >You will not cut the cone or damage the masonite when you use >the back of the blade. > >>> It's slow, laborious work, but a clean surface is mandatory >for good results.<< > >Absolutely. > >Rich Hi there Another 2 1/2 cents worth from me now. Have you tried, Acetone, which is similar to lacquer thinners, for softening the spider glue? That is all I've ever seen used up here. All safety procedures must be followed, read the safety haszard sheet, this stuff is not for inhaling. I have seen a spider come off in about 30 seconds once the glue is dampened. Just use a 1/2" wide paint brush to apply it. Good luck.

>>Hi Tom, >> >>I'll weigh them at some point if I get a chance. The former >>must extend past the windings somewhat as with most voice >>coils, do you know what that dimension is? >> > >Pete B, > >To answer your question, there is about a millimeter or two >above the coil winding, and quite a lot below the windings. >The voice coil is 2-inches in diameter and about 1.02 inches >in length. Following are images of two damaged AR#200003 >voice coils: > >(1) This AR-3a voice coil was bottomed during strife-testing, >and the nomex former and coil suffered slight damage at the >edge where the coil touched the back plate in 1+ inch >excursions during sine-wave testing. > >(2) This AR-3a voice coil was heavily damaged by extremely >high power at low frequencies, causing the coil to compress >the former when the coil hit the back plate violently. This >coil bottomed repeatedly before deforming the bobbin. > >--Tom Tyson > Hi Tom With the quality of your photos, I wish I could go back in time, to when I was working at the AR local warantee depot. When a picture is worth a thousand words, this is a great example. It might be difficult for the average reader, who may never have seen a voice coil in their life, to imagine this type of damage. The photos I would like to have shown, would be, Dynaco A-25 woofer voice coils burnt like toast, without exaggerating, charred. Common with SCA-80 and Q models which were exremely popular here, at the time. These two were mentioned only to show that the power was adequate for hifi, not disco or rock levels. AR-3A voice coils, after being plugged into an AC outlet in error. OOPs. Certainly gives, a 1 amp fast blow 25 cent fuse, a certain feeling of some security from that type of damage. Your quality photos, sure make this web site, much more interesting, to be sure. Thank you, Tom.

Hello there Ya know when I say a picture is worth a thousand words I mean it. What a great technology we have today. You could have written quite an article on describing that pot. That one picture is very well done thank you. >this is what I found > > > > 15 Ohm, 15 Watt ceramic rheostat. Body is 1.2" diameter x 1." >6mm x 0.5" long split, knurled shaft. 9mm diameter threaded >mounting bushing. Includes hardware. Large quantity available. >

Hello there Is it possible to take some photo's of one and download it to this site. >What wattage are the 15 ohm pots? > >I found some 15 ohm, 15 watt Rheostats? Is that the same >thing?