Automatic Electric N800 C50 Won't Ring

[stub]

Tim,
       Does the bottom of your phone look like this pic? Trying to see if your phone has a rheostat ( slot with numbers 1,2,3,4,5, around it)  stub

[debeaune]

Ken, John, great info as always, will do more experimenting this afternoon.  I have attached the picture you requested. Still unclear on what I am trimming off the reed? Could you please elaborate? Tim

[debeaune]

Ken, it does have the rheostat ( slot with numbers 1,2,3,4,5, around it

[TelePlay]

Still unclear on what I am trimming off the reed? Could you please elaborate?

A couple of links to check out.

http://www.classicrotaryphones.com/forum/index.php?topic=6047.msg72088#msg72088

http://www.classicrotaryphones.com/forum/index.php?topic=5601.msg68233#msg68233

There may be more, I remember one topic that shows the cut into the reed in detail but couldn't find it easily this morning and got to head off to work now. Hope it helps. Will look for more tonight.

[stub]

John,
        Thanks!! I posted it and couldn't find it.  stub

Tim,
         Go back to reply #9 ,bottom pic ,from John and just loosen the 2 slotted screws above and below the hex nut on the base of your ringer to see if you can get the clapper to move.  stub

[Scotophor]

For this style of reed, rather than cutting it to increase its flexibility, you might try something different: drill out the unused holes between the mounting points to a larger size. This should give a reduced likelihood of unintentionally initiating a fatigue crack, vs. the hacksaw method shown on a different style of reed in one of the topics linked above by TelePlay in post #18.

[TelePlay]

. . . you might try something different: drill out the unused holes between the mounting points to a larger size.

That makes sense, so what do you think of using emery cloth to sand off a bit of metal making it thinner (such sanding could be monitored with a digital caliper to see ringer improvement with metal remove, a few thousandth at a time)? I don't remember anyone using that technique. Maybe I missed it but I only seem to remember the cutting and screw loosening methods (and capacitor changes).

[Scotophor]

Of course there are many ways to weaken a flat spring such as this. I only suggested enlarging the holes because I didn't see it mentioned previously. Making it thinner by sanding, grinding etc. will work too. Another possibility would be to make it narrower by grinding/sanding away at the edges, or even trimming with a good pair of metal snips. In my own shop, I have a modest collection of springs saved from various discards including flat leaf springs, so I personally would probably just find something similar but thinner/softer and make a replacement (saving the original intact inside the phone).

Another idea is a variation on the screw-loosening method: add small soft rubber washers or o-rings above and below the reed on each mounting screw. The screws need to have some spare length available for this (which those in the photos above do not appear to have, so longer replacements would be needed), and upon re-installation will need to have extra fastening such as an additional nut added to the underside, or a drop of Loctite or super glue. Be sure to test and final-adjust the ringer before gluing, though!

As they say, there's more than one way to skin a cat! (Apologies to any cat lovers present .)

[TelePlay]

Very good multiple suggestions. This is becoming one of the better topics of all the topics on the forum dealing with trying to get frequency ringers to work as a SL ringer. Good thinking.

[Scotophor]

BTW, it looks as if nothing has been done yet with respect to ringing capacitance of this phone, correct debeaune? The photos only appear to show the original 0.08uF condenser. Before making any permanent modification to the ringer, I suggest bridging a 0.47uF capacitor in parallel with the original. This will let much more ringing current through and completely overwhelm the ringer's designed electrical resonance. You might not need to do anything to the reed after making this addition.

Also, be sure to set the rheostat to its loudest level (fully clockwise).

[HarrySmith]

Changing caps was mentioned by no suggestion offered till now. I agree, not only a reversible modification, it is also much easier to accomplish 

[debeaune]

Copy, will get the Cap installed, I have a bunch of them lying around here, will get that done asap today. Pointer on where it should go would be appreciated to be sure I'm doing this correctly.  Will adjust rheo to max, thank you. 

[TelePlay]

I seem to recall the capacitor should be rated for 250 VDC to handle the 90 VAC ring voltage. I can't recall if a ceramic is suitable or must be a metal film, or something else. Help here with all this tech stuff here would be greatly appreciated.

[dsk]

250V are commonly used, the 90V could be some greater, and in addition to the 50V (sometimes 65) so it may work with less, but this were made to last, so a little extra became common, and 250 are a commonly used voltage (=reasonable cost)
The capacitor has to be non polarized, but are not specified well.

dsk

PS modifying the ringer ? Not easy to get perfect. I would have loosend the top and bottom screws of the spring, and secure them with paint or glue. Then increased the weight of the clapper if I had something suitable, and even tried a bigger capacitor.

DS

[poplar1]

The "line compensating rheostat" should not affect the ringer one way or another. The ringer circuit is independent of the rheostat.