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Demagnetizer Product Recommendations?

Discussion in 'Electronic Repair Modifications DIY' started by adiant, Dec 3, 2011.

  1. adiant

    adiant Active Member

    After nearly 10 years away from it, I am about to embark again on digitally mastering historical audio from cassette then reel to reel tape. Back then, I simply cleaned the heads frequently. But I now note that the original Sony manuals for both my major "near-pro" consumer cassette and reel to reel decks talks about frequent demagnetizing.

    Before I pulled out my father-in-law's venerable Radio Shack 44-215 Head Demagnetizer, I googled a bit and discovered that some believe that it is not powerful enough to do the job.

    Some of the folks who had actually done servicing stated that the Han-D-Mag made by R. B. Annis Co. is the only affordable demagnetizer that is powerful enough to properly do the job, especially for capstans and other solid metal pieces in the tape path. Here is a typical article: Cleaning and Demagnetizing

    Does anyone have any experience to confirm or deny the Han-D-Mag recommendation?
     
  2. Steve@Russo

    Steve@Russo Active Member

    han-d-mag seems to be the norm
     
  3. RemyRAD

    RemyRAD Guest

    Back in the day I was a factory authorized service technician for Ampex, 3M, MCI, and I worked for Scully. That is the DE-magnetizer to use. It's powerful enough to deal with 2 inch tape recorders all the way down to cassettes. In fact it's so powerful, it can be used as a analog cassette bulk tape erasure. That Radio Shaft and others like it are barely appropriate enough for cassette decks.

    One may not understand that there is actually a right and wrong way to DE-magnetize. There is a technique that if done incorrectly can actually do more harm than good by actually magnetizing the heads. And while you indicated you have read this should be done often, that really isn't completely correct. If you are rolling lots of tape, the magnetization of the tape can have an effect on the playback head, leaving residual magnetization behind. Record & erase heads are generally self DE-magnetizing by virtue of the higher energy electromagnetic current sent into them. But that's not true for the playback head. Plus, if you transport your reel to reel recorder much in a north to south or, south to north direction much, the magnetic field of the earth will cause the heads to become magnetized. This doesn't happen if you are transporting your recorder predominantly east to west or west to east. How about that? And one should always proceed to DE-magnetize the heads before ever placing or using a expensive calibration reference alignment tape. Otherwise, once a month is generally adequate.

    Now to the technique: you start with the tape guides. You move on to the CAPSTAN. Tape guides, idler rollers. You proceed to the Erase head where you will gently move the DE-magnetizer, Top to bottom, bottom to top a couple of times. But you do not turn off the DE-magnetizer but rather, you leave it on and you pull it very, very slowly, parallel to the face of the head until it is approximately 6 feet away. You continue on to the record head. Before you get to the play head, make sure the machine is not sitting there idly in playback mode. This could actually damage meters and/or head preamps. This procedure must be done wherever the tape comes in contact with. The last thing you DE-magnetize, is the playback head.

    I could go into more depth & detail but this is the general gist of it all.
    Mx. Remy Ann David
     

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