Loudspeaker magnets: magnetizing fixture?
Hello again
a year or so I bought a 2440 with a mis-alignment at the top plate.
Questions arised, how to fix it? demag it or use a hammer? Searching for companies in Norway or Sweden who could possibly demag and re-gauss it after the mis-alignment have been fixed?
It was then I got the bright idea to build my own magnetizer.
Ok, I bought parts from eBay for nothing and read the paper: Methods of Magnetizing Permanent Magnets (by Joseph J. Stupak Jr. 2000).
My magnetizer will be capable to push out 6-8 kJoules in this moment but I could get more out of it if buying more electrolytic caps at the eBay auctions.
When the magnetizer was in the step/level to funktion I made some tests. It worked and the first object to test it to was to demag the bad 2440. Yes, it was a very exiting moment when I easily could lift of the top plate at the 2440s motor.
I fixed it and re-align the top plate, well it was then the real work could take place: constructing of a magnetizing fixture (or two fixtures). But that job was hard to do because I couldnt find any relevant information when searching the internet, so I couldent figure out how to construct the fixture.
Is there anybody (eg. "rbrooks7" and "pelly3s") at this forum who have realy seen a loudspeaker magnetizing fixture or could describe it in words (inductans, ohms, turns etc).
Thanks in advance
Regards
Photos and data would be fine
pelly3s wrote
Quote:
i'll also try to take a couple photos if i can remember. sorry i cant be of too much help at this moment.
pelly3s, hope you can post some photos at the Forum. I think not only me have an interest in to see how a magnetizing coil looks like. Would it be possible for you to measure the inductance of the particular coil if data is not available?
Could you tell us, okay -me what is the value of the caps in your machine?
do you know what is the voltage you zap through the coil? Do you use it to all JBL models or do you have different sizes of coils ? I plan to build two different coils. One to suit the bigger JBL models like the 2440/375 and 14-15" cone speakers. And a one to suit smaller models like the LE10, LE8, 077 etc.. Maybe it is not necessary to build two different coils, maybe it will do with only one size coil? Whats your opinion?
Robh3606, thanks for the link. I have seen it befour, many years ago.
Regards