- speaker refoam - 1 Update
- ME/MA UK 1970's transistors? - 5 Updates
| jurb6006@gmail.com: Nov 18 06:37AM -0800 >"Applying tones to hear when it rubs works well." I do that. I use a function generator on sine and set it to the free air resonance frequency It is easy to see, whatever frequency moves the cone the most. Then I see which way it might have to go to be in the most perfect center. It could be fine without touching it but I push it both ways on both axes to find which way the bent bends. Whichever way I got the most clearance before the voice coil rubs is the direction I "coax" it to before the glue dries. Once I had to fix one someone else had done. He thought it would require removing the glue and tearing everything out. Nope. I simply bent the frame slightly. Of course this will not work on speakers with cast frames so just be more careful on those. Actually there is money doing that. I heard of a guy in my state who started doing a few and still worked. In a couple of years he quit his day job to do this full time and makes decent bucks doing it. He can't keep up with the work. I am considering doing it. All you need is a little bit of exposure and a few satisfied customers. And of course I would have a discount for cash... It would tie in nicely with any of my stereo fixing endeavors as well, it would be practically the same customers. And audiophiles go in packs, at least on the internet. Of course some of them will fly cross country to hear another's system, but when your system cost more than a new car you do things like that. |
| frank@invalid.org: Nov 17 08:44PM Hi all, I'm restoring a couple of 1970's wooden case acoustic coupler, both made in the UK. I haven't find the slightest bit of information about both of them, just some pictures on the net. One of them is the DCD model AC.350.OM (where probably OM stands for Originate, as it doesn't have any Orig/Answ switch). Now, I'm checking most parts (it's made on 6 PCBs, plus some chassis-mounted components) for obvious problem, like diode/BJT junctions, carbon composition resistors values, electrolytic ESR/shorts etc. All transistor have MAxxxx or MExxxx codes, they really look like BCxxx transistors from the early 1970's, one of the most common ones is ME4101. By the way, the ICs have 1972-1974 date codes, so this unit was probably manufactured in 1974. My first question is: does anyone have a cross reference for these MA/ME transistors? Are those a kind of military markings? Second question: almost all ME4101 have a junction voltage drop around 0.8V but one of them shows a bit more than 1V drop on both BE and BC junctions (it's NPN). Can I assume this one must be bad? Any other hint and information is welcome. Thanks Frank IZ8DWF |
| tabbypurr@gmail.com: Nov 17 12:46PM -0800 > Any other hint and information is welcome. > Thanks > Frank IZ8DWF 0.8v V_be is odd. Something isn't right there. NT |
| tabbypurr@gmail.com: Nov 17 12:49PM -0800 > Any other hint and information is welcome. > Thanks > Frank IZ8DWF http://pdf1.alldatasheet.com/datasheet-pdf/view/75282/MICRO-ELECTRONICS/ME4101.html NT |
| Phil Allison <pallison49@gmail.com>: Nov 18 02:14AM -0800 > but one of them shows a bit more than 1V drop on both BE and BC junctions > (it's NPN). Can I assume this one must be bad? > Any other hint and information is welcome. ** ME4101 etc devices were made by " Micro Electronics" of the USA - Silicon Valley address. http://www.microelect.com/ Made a lot of types in TO106 package - shiny, glob tops and gold plated leads. Very neat looking. .... Phil |
| John-Del <ohger1s@gmail.com>: Nov 18 06:30AM -0800 On Sunday, November 18, 2018 at 5:14:51 AM UTC-5, Phil Allison wrote: > Very neat looking. > .... Phil You got me curious. Here's a link to a picture. I remember seeing similar transistors years ago in Zenith TVs. https://www.radiomuseum.org/images/tubephoto_klein/me4101_1.jpg |
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