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Author Topic: Bulk Tape Erasers / Erasure  (Read 4633 times)

Offline stellavox

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Bulk Tape Erasers / Erasure
« on: October 16, 2015, 09:14:53 AM »
A fellow tapester mentioned a problem he's having - trying to erase a pre-recorded tape using a "bulk tape eraser".  I realized that I'd experienced the same problem and thought I'd throw it out to youse guys.

First of all; let me describe what I'm talking about, for those of you who may not be familiar with the term.  A "bulk" tape eraser is a big box, typically with a little post on it, that you can "mount" a whole reel of tape on.  You plug the cord coming out of the big box into a wall outlet, push down an "on" button somewhere on the box, and typically hear a hum as the GIANT AC ELECTROMAGNET inside the box erases the tape - also demagnetizing ANYTHING ELSE within a 2 foot? radius.

The erasers I had could only handle 7" reels max and I'd lost any instructions: so I tried various techniques - like spinning the reel slowly (while pushing the button) - maybe one revolution on 5-10 seconds; then turn the reel over and do the other side.

My friend mentioned that he tried this/these but gets a "whomp - whomp - whomp.... sound when playing back the "supposedly" erased tape.  Yep, I remember that. SO what are we doing wrong / were do we go from here????



Offline docb

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Re: Bulk Tape Erasers / Erasure
« Reply #1 on: October 16, 2015, 09:34:14 AM »
Might be something as simple as making sure the reel is turning before the button is pressed and keeping the reel moving for second or two after the button has been released. But I could also be wrong. Makes one wonder if locking the button on and bringing the eraser up and down with a variac instead might avoid any magnetic pulse.
Dan "Doc B." Schmalle
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Managing Director - retired, The Tape Project

Offline ironbut

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Re: Bulk Tape Erasers / Erasure
« Reply #2 on: October 16, 2015, 11:22:08 AM »
This comes up every now and then on the Ampex list.
The rotation of the reel is to prevent this pulsing. It needs to be steady and constant. It's supposed to be better if you move the reel off of the eraser in a smooth movement while the machine is still on (just like on heads).
If it's a good (powerful) eraser, be care of watches, bank cards etc.
Sometimes it's just that the machine isn't working correctly but, just off the top of my head, I seem to recall that repeated applications decreased the pulsing.
steve koto
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