[AMRadio] Residule Magnatism


John Coleman ARS WA5BXO wa5bxo2006 at pctechref.com
Sat Sep 16 23:38:21 EDT 2006


In the cannon laser jet SX series printers released as HP Laser Jet II, and
other brands as well, there is a solenoid device which releases a clutch
which then allows the paper pickup rollers to move paper through the
printer.  These devices have a felt pad between the armature and the pole
piece which I once thought was only to keep down noise.  Then one day I
begin to see a lot of sticking solenoids and investigated the failure.  The
felt pad along with the glue that held them in place had changed to a mushy
substance that was not releasing the armature and so it would continue to
feed paper after all the printing was done.  I said to my self, "Well I will
just scrub that stuff away and let it make a little noise, so what".  Well
it turned out that with out the non magnetic material in between the
armature and the pole piece the residual magnetism would not release the
armature either.  So I glued a little piece of thin plastic in place and all
was well.  It was a little noisier that the felt pad but not bad.

John, WA5BXO      






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