I disassembled a vcr... and " what the hell?" hel

[LUNCHBOX9000]

Ok... Please someone answer this for me! So, I take apart a VCR and among the various motors and the various parts of these motors; there is a piece of one of them that does'nt quite fit. As far as it goes I do know the roughly basic, and not so basic components of a number of different electric motors... This is generally the one that is the "shiny cased" larger one, and that should fairly well let you know which of the number of motors I am speaking of(if you choose to take a VCR apart for my questions sake). So what it is about it that gets me is that first of all once taking it apart you will see that the disc shaped ferrero magnet has an outer case on one side (once apart) that is magnetic only on the exposed magnets side. The other side is "some" metal that appearantly is impermeable to magnets altogether, the side from a profile is only maybe 1/4 of an inch, leaving the remaining metal casing to be less than 1/32. One side will pick up a wrench and the other won't even pick a BB or a small spring up. So that is confusing enough, seeing as the only thing even closely explaining my problem would be " dielectrics" which in this case is simply not it; and you know why if you have understanding enough of stuff. A metal may be non- conductive and impermeable to magnetism, but there is no metal of any sort that bluntly kills magnetic attraction!

 

[cameo_2007]

o my o,
i read 3 times,i didnt yet understand the overall picture.
what is the question in that.?

 

[touringmike]

Re: I disassembled a vcr... and " what the hell?"

I don't know what the question is, but the answer is Buy a new VCR.

 

[spectrabei]

Re: I disassembled a vcr... and " what the hell?"

Hey Lunchbox,

Maybe ya aught da switch to lean cuisine. sounds like your dc motor got discombobulated and threw a rod. that dern monkey wrench just Jumped right off that derned table and SMACK, right in to that gall derned motor and magnetismic parts started Flyin ALL OVER THE PLACE. But Ya Know What Lunch, (hope ya don't mind if I Call ya Lunch) YER BETTER OFF FOR IT. Yes YOU ARE, and you know why mr. Box, cause you can go right down to that big ole store, OOH you know the one, It's ON THE Tip OF my tongue, It's commen to me, give me a sec here........ WA..WA..WAL--WallMMMM ----- WALMART, THATS IT! somebody shuck my corn cob cause I got it right! Yes sir, like I was sayin, you can go to that derned walmart and by another VCR for only 20 dollars!!! And just ta be on the safe side I'd pick me up another monkey wrench to..

Bye Ya'll

 

[LUNCHBOX9000]

Re: I disassembled a vcr... and " what the hell?"

thank you for answering my question.... there is no intelligant life out there!

but i geuss you knew that to..

 

[spectrabei]

Re: I disassembled a vcr... and " what the hell?"

Mu-metal is a nickel-iron alloy (75% nickel, 15% iron, plus copper and molybdenum) that has very high magnetic permeability. Permeability is represented by μ, the Greek letter mu.

The high permeability makes mu-metal very effective at screening static or low-frequency magnetic fields, which cannot be attenuated by other methods.

Mu-metal requires special heat treatment — annealing in hydrogen atmosphere, which reportedly increases the magnetic permeability about 40 times. The annealing alters the material's crystal structure, aligning the grains and removing some impurities, especially carbon. Mechanical treatment may disrupt the material's grain alignment, leading to drop of permeability in the affected areas, which can be restored by repeating of the hydrogen annealing step.

Mu-metal is very expensive and its doubtful that its in any VCR. The high magnetic permeability core of which you speak is called ferrite. This is part of the electromagnetic recording head. There are 2 recording heads and 4 recording head VCR systems out there. These heads are located inside a rotating drum, called a Head Drum Scanner. The rotating head scanner Drum has a top( which rotates) and a bottom (which is Stationary). In the rotating top section there two recording head systems. The heads are located 180 degrees apart, in a 4 Head Drum Scanner they are positioned 90 degrees apart. The 4 head Drum Scanner (and 2 head Drum Scanner) Rotates at a speed of 1800 RPM. In order to get the signals from the electronics of the VCR to the rotary head(and ultimatly the tape) the method of (rotating) transformer coupling is used. The Stationary section of the drum holds the primary windings and the rotating upperdrum contains the secondary. Ferrite shaped core pieces hold the windings. The low reluctance path provides good magnetic coupling. In recording, the signal is connected to the stationary winding as the primary, with magnetic coupling to the rotating secondary winding. In Playback, the rotating winding acts as the primary, coupling the signal into the stationary winding, which acts as the secondary. I believe this is what you were talking about. I understood what your question was right from the start but because of extreme tiredness (from exhaustion) I was trying to wake myself up with a little levity.. No offense was intended.


Regards from (A pretty good deal for 20 bucks, huh) SpectraBEI