Originally posted by Lowell Goudge i have a different quesdtion.
has anyone looked at demagnetizing the parts? common process on old tape machines,
What do you want to demagnetize?
Old tape machines would not magnetize necessarily: Only 3-head tape-machines needed demagnetizing.
2-head tape-machines demagnetize everytime one recorded because the bias automatically demagnetized the head!
With a 3-head tape-machine the playback- and recording heads are separate and thus the playback-head does not receive and bias i.e. demagnetizing!
Particular older tape-machines had softer material on their heads which could magnetize easier and needed therefor attention.
A tape-machine head is made out of ferromagnetic material (as opposed to paramagnetic materials such as air, aluminium, platinium etc. and diamagnetic materials such as water, copper and very strongly pyrolytic carbon). There are better materials and not so good ones. Permalloy, Sendust, Ferrite etc. But all are ferromagnetic and thus will strengthen a magnetic field (either a permanent magnet or an electromagnet!). It has an effect when it is in contact with the magnet and can even saturate. When it is away from the magnet it the left over magnetism goes quickly away, but this is of zero interest to us because with this solenoid the ferromagnetic plunger is 99,999% of its live in contact with the magnetic field of the permanent magnet and ... receives another magnetic field from the electromagnetic coils which counteracts that one of the of the permanent magnet.
So it is of zero interest if the plunger would have left-over magnetism, of course it has but only for a short time. The interest is how it behaves because it is
in touch with a magnetic field!
But when it is away for the short time the leftover short magnetism is of zero interest either because the solenoid then works.
So you could only demagnetize the permanent magnet and then the solenoid wouldn't work anymore.
The problem of the solenoid is linked with several factors and Ricoh has not yet solved it completly but they made it better.
And yet some K-70 solenoids do fail.
---------- Post added 06-14-19 at 07:22 AM ----------
Originally posted by pvanni Present! I substituted the solenoid on my k-30 with the white one and after some months the black picture problems arised again.
Actually I can only take pictures using the AA battery adapter, with the li-on original battery only in continuous drive mode and only some
pictures are correctly exposed.
Very rare that this happens. There are few white solenoids on the market which actually have a stronger holding force. I have a few here for my records.
They look identical. And if the person who sold them to you got some of those, too bad.
Also some use the white solenoids from analog bodies such as the MZ50 or MZ6. Those solenoids are slightly different and some even have opposite polarisation!
I have explained this in my manual.
The problem can also arise, if one tried too long with the defunct green solenoid and particular if one tried "to losen it up" with series shooting!
Or with AA batteries because one runs the complete diaphragm-control-unit, a quite complicated and actually clever and wonderful designed part...
well.... with a faulty unit. What to expect?