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tmoravan wrote:
OK - before I replace these worn out tapes, how doI know if I did a
thorough job demagnetizing the tape heads? I know there's
magnetometers (gaussmeters) out there, but in fact, has anyone
measured the magnetic field strength of a tape head when it's
magnetized and/or after being demagged?(Just being paranoid - don't want to wipe the high end out testing my
work).
Greetings Tom and everyone,Alwayd best to demag the heads and headblock when performing
any service in that area. I recently cleaned/polished headson
M400/1428 and replaced a suspect tape head. (Thanks foryour
help, KL !) First order of business was to demag every head ,
since my hand tools were suspect .Not sure what field strength of magged vs. demagged heads might be.
VERY tiny, I'd guesstimate. Zero Gauss for demagged-heads, obviously.For general Mellotron svc. easiest way to avoid magging the heads
is to install a 47 K-Ohm resistor across the connector inside the
M400 preamp. Reason for this is to dissipate the charge of
Capacitor C2 (20uF@6V) each time headblock is removed and
reconnected. This is an old modification first done by Sound Sales
then by DK and now the majority of us who own/service Mellotrons.Cheers, Jerry Korb (c/o North Country Restorations)