De-magnetizing tape heads

[Netlist]

My old AIWA F990 does the job automatically. It’s a clever circuit with a relay, activated for a few seconds, every time the deck is switched on. Maybe there’s something to DIY here.
Then again, only the head and no surrounding parts will be demagnetized.

/Hugo

[anatech]

It's like a television degaussing circuit. The playback amp should not allow any DC current to flow in the head windings, and there is no reason for most tapes to become magnetized in one pole unless your tape gets stuck to a magnet, or or use a cheap cassette deck. The exceptions are the really old machines.

Most people do more damage demagetizing their own deck than if they had just left it alone.

-Chris

[netwalker]

Yes, that`s true with the demagnetization. I have a DM-10 this is a good one, I`ve demagnatized all my screwdrivers, also I`m doing a demagnatization on all screws and nuts because I`ve read that this should be done. But demagnatizing a deck with it is a little awkward. First of all you don`t get propperly in where you should. and you actually don`t know what you`ve done because I don`t have a meter for this. Small circular movements, someone says, switch it on and then get in, someothers say get in and switch on, switch always off far away from the deck. Deck is sure off, but how can you do a damage. Also it is said to demagnatize all the path where the tape travels, this means heads, guides and also capstans. But the capstans on the dragon for example are driven by a PLL motor and both capstans have round magnets glued on them. Can you damage these magnets with the demagnetizer and so damage your capstan motors ?
Generally, away from motors ? What do you think and how do you do this ? Best regards,
Plamen

[anatech]

Never switch on or off near the deck. The capstan shafts are unlikely to become magnetized in normal use.

For the Dragon, remove the door and tape lifter, demag the heads only. Reassemble.

-Chris