kj2005 Posted February 12, 2020 Report Share Posted February 12, 2020 Hi, I have erlier tried to repair the tweeter for AR10pi, and I was lucky because the wire breaking point (or heat-meltingpoint) was placed approx 1mm from the coil. This type of repair with the old-style tweeter and the paper cone is more difficult..... but so far I have been able to get the disconnected coil out without doing any harm to the coil-shape. I have drawn approx 3-4 cm out of the coil to find the melting point, and I found it....the coil measures 6,6 Ohm so it should be ok now.....First some pictures and explanation later. I am not sure if this is going to be a succes..we'll see? Rgds Kim Quote Link to comment Share on other sites More sharing options...
GD70 Posted February 13, 2020 Report Share Posted February 13, 2020 I hope you're successful! Member Chris1this1 is rebuilding these tweeters with great success. When I got my LST-2's, all 6 tweeters were dead. No one was repairing them at that time. I replaced them with the HiVi Q1Rs recommended by Roy C. With some minor crossover mods, they sound fabulous! Good luck, and keep us posted as you progress. Quote Link to comment Share on other sites More sharing options...
kj2005 Posted February 15, 2020 Author Report Share Posted February 15, 2020 Thanks for all the good thoughts....I hope to get sound out of the tweeters, and today I have to buy some "liquid rubber on tube" that hardens in contact with oxygen. Another thought was that many americans are very close to the "source" as far as 0,75" inch tweeter coils is concerned ! Look at this : https://www.aliexpress.com/item/32892542036.html?spm=a2g0o.detail.1000014.3.2c0c55faDijlw5&gps-id=pcDetailBottomMoreOtherSeller&scm=1007.14976.159745.0&scm_id=1007.14976.159745.0&scm-url=1007.14976.159745.0&pvid=dbf61399-26d8-489d-966c-2dbd478227f6&_t=gps-id:pcDetailBottomMoreOtherSeller,scm-url:1007.14976.159745.0,pvid:dbf61399-26d8-489d-966c-2dbd478227f6,tpp_buckets:668%230%23131923%2318_668%23808%233772%23972_668%23888%233325%231 At AliExpress you can buy a lot of two inner coil diameter 19,43mm 5-8 Ohm tweeter coils silk-dome for 3,58$....looks like kapton coil form to me? If the silk-dome does'nt fit you might be able to use the coil's? Anyone who tried this? rgds. Kim Quote Link to comment Share on other sites More sharing options...
kj2005 Posted February 17, 2020 Author Report Share Posted February 17, 2020 Well, after some challenges i have repaired one (1) out of four disconnected LST-2 tweeters. KlausM explained to me that the swedish car-store "Bil-tema" (car-tema) sold 15 grams liquid rubber for approx 7$...I bought this liqiud rubber that hardens within 12 hours ... it works with one drop on the three fix points on the tweeter frontplate to keep the voicecoil in place. To recreate the softer "spider" suspension between the tree "dots", I used the water based contact glue from Audiofriends.nl. This glue is normally used for new woofer surrundings, but in this case you can make a thin layer first, and if coil moves too light it is possible give the coil edge one more thin layer . To check the coil polarity you can check with a used 9VDC battery well down to approx 4,0VDC. Before centration and glue place the loose tweeter coil in the voicecoil -gap....if you connect the 4,0VDC battery to the the tweeter voicecoil with correct plus polarity, the coil will try to get out and away of the magnet-gap...easy test. Less talk...here are the foto's 5-6mm paper arrows used for centration....clear tape used for isolation of the wires....voicecoil approx 6,4 Ohm DC resistance (test wires measures 0,3 Ohm) Rgds kim Quote Link to comment Share on other sites More sharing options...
kj2005 Posted February 20, 2020 Author Report Share Posted February 20, 2020 Last info concerning LST-2 tweeters Four tweeter coils repaired .....kapton coil forms hardened with thin layers of cyanoacrylate.... under 40x magnification by slit lamp (normally used for contactlens control) 2 tweeter plays .... No. 3 & 4 mounted....litzewire still missing ......all 4 tweeter coils stays within Re 6 ~ 6,4 Ohm Liquid rubber from ”Biltema” should be used to as minimal extent as possible because this "suspension" easily becomes less resilient than the original ”AR suspension”. The result is a lower sensitivity than the tweeter initially had. After some experiments, the following came to suit subjectively ...... if possible: one could recommend a "half" drop of liquid rubber ( 3 x 2 mm) at the three fixing points on the metal faceplate and a suitable "thick / thin" mixed water-based contact glue as " suspension "between the three" rubber points ". Without measuring equipment, is it not possible to determine whether the repaired tweeters has the same output as the originals? Rgds. Kim Quote Link to comment Share on other sites More sharing options...
GD70 Posted March 4, 2020 Report Share Posted March 4, 2020 Impressive work! Great to see and read your process, and success! Quote Link to comment Share on other sites More sharing options...
kj2005 Posted March 14, 2020 Author Report Share Posted March 14, 2020 Wood repair and finish test....They sound great by use of a complete renovated NAD 3080? My friend was very happy with the sound. In his opinion they were back to factory standard? Rgds Quote Link to comment Share on other sites More sharing options...
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