Archive of the former Yahoo!Groups mailing list: Mellotronists

 

kenmerb@... wrote:

 
Jerry,

   What's the policy / procedure on demagging the heads on a MKII?  Isit the same as for an M400?  I should know this, but I don't (andobviously haven't done it with mine).  KL and I have discussed thisin the past, but never asked anyone who knew the answer.  Others mayfind this interesting.    Ken M.

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KM and gang,

The headblockson MK-I and MK-II models are high impedance.
They have approx10X resistive measurements of the later models.

All solid-statepreamps are low-impedance, while true valve preamps
are high impedance.I checked the schematic for PA1 in the MK-I/II's.
There's no capto worry about  as in the M400's . And the valve itself
is open-circuituntil powered-up.

I'll go out ona limb by saying that  Demagging a MK2 headblock
is the same asM400,without the worry of plugging it back in.
Comment is invited,pleasecorrect me if in error.

In Frank's Pindertron,the Hi-Z headblocks are mated to balance
transformers,w/odirect connection to the transistor preamp cards.
This config.is also safer than stock-M400 demag. procedure.

Thanks, Gene Stopp,for your input  on magnetic field strength.
I should emaila buddy of mine who works at FermiLab in
Aurora,IL onthe superconducting-collider. He'd know for-sure !

Cheers, JerryKorb (looking for the "Z" particle w. Mellotron heads)