Ringer Loses Magnetism When it is Disassembled

[HarrySmith]

OK. Good luck.
As far as I know they were interchangeable as are most other parts for the 500's. Maybe one of our Canadian members will have a ringer for you, much cheaper to ship!

[JorgeAmely]

It is interesting that the post published by Dennis in 2009 is still gathering interest among forum members.

Anyway, Google has gotten way smarter thanks to AI and it is capable of answering more precise questions about the topic of removing magnets from magnetic circuits specifically.

I asked this question: "Why magnets lose their magnetism when removed from a magnetic circuit?" and got the following response.

So, unfortunately, the strength of a magnet decays immediately when removed from a ringer. 

[MMikeJBenN27]

But how much per minute?  Like I said earlier, I have disassembled ringers and had no problem with them after putting them back together.

Mike

[TelePlay]

Like I said earlier, I have disassembled ringers and had no problem with them after putting them back together.

Probably depends on the type and quality of the magnet. I would think older, turn of the century magnets, were of poorer quality than post 1950 magnets and would lose their field faster.

Some modern magnets don't require a keeper. What might work is to put a very strong modern magnet on the reassembled dead ringer and let it set, let the particles align, for a few days to a week.

One can get a relatively small 400lb pull Neodymium magnet for about $10.

[DuinoSoar]

Thanks for all the responses and contributions, folks.

But how much [magnetic strength is lost] per minute?  Like I said earlier, I have disassembled ringers and had no problem with them after putting them back together.

Unfortunately, I left mine disassembled for a few days before I got around to cleaning the individual parts.  I had disassembled the whole phone for cleaning (including disassembling the ringer parts), then worked at cleaning it up, off-and-on, over period of a couple of days, to clean the plastic shell, handset shell, finger-wheel, dial-plate, etc.  So, after the ringer had been disassembled for a couple of days, I finally got around to cleaning the base plate and the ringer parts, and then put it all back together.

So, from reading the references linked by other folks in this thread, I am assuming that I left the ringer disassembled too long, and that the delicate balance between the magnet's (now reduced) field strength and the striker's bias spring is now "out of whack" (double-entendre intended ).

@TelePlay: I do have a few "hobby-level" neodymium magnets stored away somewhere, but none would be strong enough to pull 400lb. Is there some clever way I can use what I have, to re-magnetise the C4A ringer's magnet?  I cannot think of any ferro-magnetic material that I might have on hand to complete a magnetic circuit with the C4A magnet and my neodymium magnets.  And for re-mangetising, is there an upper limit as to the field strength it should have?

But really, it sounds like the easiest route is to just obtain a new ringer (if I cannot get my present ringer to work with a new capacitor; I am waiting for some 0.47µF, 600V polypropylene capacitors to arrive, and will try using one to replace the A-K cap in the network "box").

[DuinoSoar]

Well, it turns out that my NE 500 will ring - sort of.

My C4A ringer does not have that "G-shaped" retainer for the bias spring (with the two spring positions).  Instead, it has two notches into which I can move the spring: the left one for higher spring tension, and the right one for lower tension.  In either of these two positions, the phone will not ring.  BUT, if I remove the spring from both notches and let it go all the way over to the right (close to the adjustable gong), the phone will ring, but not as loud as I would like.  See the pictures below.  When the spring is in the "high" or "low" setting, there is no ringing; when it is in the "lowest" setting (i.e. completely released), it will ring.  This is true whether I use the "A-K" capacitor in the 425 network, or a new 470nF capacitor (non-polarised polypropylene cap rated at 400V)

So it looks like I probably weakened the (not so) permanent magnet by leaving the ringer disassembled for too long.  BTW, my ATA will ring an AE 40 just fine, so the problem is not with the ATA (a Rogers Ignite gateway that supports "home phone" service).

Anyway, I will leave the bias spring disengaged (as in the last photo).  There are other phones in the home that will alert me to an incoming call if I do not hear the NE 500 ring.  I may try replacing the ringer at a later time.

Ed.

[TelePlay]

Here's a 600 pound pull Neodymium magnet which if placed on the ringer with the correct polarity and the ringer ferrous metal tapped to the let the magnetic particles in the iron move to one direction, realign, it may restore your ringer's magnetic field.

I've intentionally, and unintentionally, magnetized ferrous metal a few times in the past. I remember using the magmatic windings of a running electric motor to make a screwdriver blade magnetic to hold ferrous screws.

Others may have other suggestions.

[DuinoSoar]

... if placed on the ringer with the correct polarity ... it may restore your ringer's magnetic field.

So there is the possibility of error by placing it with the wrong polarity (how does one figure that out and where, exactly, would that "fishing magnet" be placed?), and the use of the word "may" implies that it might not work anyway.

I checked ebay.ca (the Canadian version) and looked up prices and shipping of neodymium fishing magnets AND C4A ringers, and it seems that just getting a new ringer would be easier.

But as I wrote before, I will stick with the status quo for now (just leaving that spring disengaged) and maybe consider getting a new (or "new-to-me" ) C4A ringer at a later time.

[TelePlay]

On the second page, I show a transparent green sheet of plastic that shows the magnetic field. It's reusable.

Green plastic magnetic field indicator

I used a simple compass to determine the north and south of the ringer magnetic.

You would do the same for the magnet, out simple hang the powerful magnet from a string and lower it down to the ringer, it will align the fields.

South attracts north, south repels south.