WWI 1917 Field Telephone Ringer Problems

[twocvbloke]

My multimeter is one of these:

http://tinyurl.com/csvmuoa

Though I paid slightly more for it (£9.99 I think), and I replaced the probes with something a little more sturdy, and even now I need to replace them...

It's handy for general use, wouldn't want to try it on high voltage as it's not designed for it, but for low and even Mains AC voltage, it does the job...

And despite the picture depicting a backlit LCD, it's not backlit, the other model I had, which was very similar in specs which got ruined when it tried to drink coca cola, did have a backlit display which was handy, but they don't sell it any more...

[hatrick]

dsk... thanks for the advice on which multimeter to buy.  Since I don't know anything about multimeters, I'll get the one you recommend since it is only $25 shipped

http://dx.com/p/3-0-lcd-handheld-auto-range-multimeter-voltage-current-resistance-temperature-2-aaa-37383

Once I get it I'll let you know what the readings are.

Thanks,
Eric

[twocvbloke]

Hmm, looking on DealExtreme there, they have my old meter, plus it's variants, and my current meter  it's variants too...

http://tinyurl.com/d75xwv5

Nice meter, doesn't like coca cola though...

[HowardPgh]

Are the handsets on hook when you try to ring the other phone?
A receiver off hook can cause  the phone to crank "heavy".
Howard

[hatrick]

Howard,

The handset on the phone that I am cranking (which is the tough one to turn) is off the hook while the handset on the phone on the receiving end is on the hook.

I also tried it with both handsets on the hooks and it is still a problem with the one phone.  You are correct though... when I have the handset off the hook on the phone that seems to be working good it does get heavier cranking the ringer compared to having both handsets on the hooks.

Eric

[hatrick]

I just received my multimeter as recommended by dsk... now I just have to figure out how to use it as the instructions are pretty poor for a newbie like myself.  Any help on how to set the multimeter and zero it out before taking the readings would be greatly appreciated.  Also, should I be taking the final readings with the two phones wired together or just as separate stand alone phones?

Thanks,
Eric

[dsk]

To use the meter as an ohm-meter, turn the switch 2 steps to the ohm symbol, and wait about 2 sec. Ready for measuring  The 2 probes should be connected to com (usually black) and  VΩHz (usually red). The meter is auto-range so it needs a little to get a stable reading, but shorting the 2 probes should give you a reading = 0 or 0.1 if you are holding the quite firm together.

Now just measure between the line terminals of the telephones without connection between them, and in on hook position. 

dsk

[hatrick]

One phone reads 123 ohm while the other phone started at about 18 M ohm and continued climbing slowly until it reached O.L (overload I assume).  Both tests were done with the phones disconnected from each other and the batteries removed and the testing taking place on the L1 and L1 connectors.

Thanks,
Eric

[dsk]

Sounds reasonable
The one ending on O.L. is the working one!
Here the generator (inductor) is shut off when not used, a capacitor in series with the ringer causes a sliding reading in direction of nothing to measure. ( = to measuring nothing, just open circuit)

If you go off-hook you will get a new reading of resistance (probably) of less than 200 ohms.

The other phone has generator permanently across the line.
If you opens it up, you may see why the switch not are working, maybe a drop of thin oil on the gear and bearings may help. It is easy to use to much oil!
If you cant figure out whats wrong, you could try to remove a wire from the inductor, and measure again.

Looking forward to hear how it turns out.

dsk

[dsk]

The inductor may look like this one.
Please note all moving parts will like oil were friction could be reduced except from:
Shaft ends touching electric contacts, and electric contacts.
dsk

PS Red arrows are examples on no oil points, and black arrows are please lubricate here points.

As you see this one has got to much oil some years ago, and collects dust (=trouble)

DS

[hatrick]

So I took apart the other phone with the 120 ohm reading and blew it out with compressed air and oiled the crank and other moving parts of the inductor and still no luck getting the ringer to work both ways.  I was able to get a OL reading now but still when I crank the other phones ringer it is very heavy and doesn't ring either phone.

To further confuse things, I borrowed a super nice 3rd phone from a friend and oddly enough, this third phone works fine with both of the phones I have in both directions with the ringers.  But when I hook up my two phones again, the can only ring in one direction.  This is really confusing me since both of my phones work fine with this new, third phone but don't want to work together.

Would pictures of the internals on my phones be helpful?

Eric

[dsk]

Strange results.

If you could test the 123 ohms reading again.
If it not has changed to O.L. try to remove the handset wire from the G terminal, and measure again.

Pictures, I don't know if it helps, but it doesn't hurt. Especially the contact positions on the cradle switch in on and off hook positions may be of interest, and the same about the contacts on the generator who should move when you turn the crank to almost rotating the gear, and should move back when you release the handle.

The fault is obviously something I don't have had in mind yet, so other pictures may help as well.

By the way, in on hook position but not connected to any other phone the generator should ring the internal ringer, does it ? On both phones?
Did you feel significant difference in resistance when you cranked your friends phone calling each of your phones?

dsk

[hatrick]

I can't seem to make sense of it, but when I went to start tinkering with the phones today, for some reason the ringer was working in both directions on both phones.  The ring could be a bit louder but it is working pretty well.  I'm sure the ringer was never too loud to begin with based on the design of these phones anyways. I can't explain it but who knows.

So the only thing that is still in question is getting the 4-wire handset to have sound in it when you are talking with it.  I am wondering if I should try having a wire go from one of the receiver terminals to one of the transmitter/microphone terminals (inside the handset) before going down to the phone itself.  I do have the 4th wire attached to the red terminal as instructed but still can't hear yourself talking with the handset.  The sound is ok on the receiving phone but it is odd talking into a dead sounding handset.  Any thoughts??

Thanks,
Eric

[dsk]

What should I say?
Be happy it works   What about the resistance? Maybe the use and handling has made the spring in there moving again?

When you have your handset configured so the transmitter and receiver are put in series, either by having a common wire, or connecting them in series by connecting 2 wires commonly on one terminal you should end up with a testable simple circuit.

Putting in a battery in this circuit  you should be able to hear yourselves.
When this works, its just to connect it to the telephone.



You may use the batteries form your telephone. 4.5-9 volts should be OK

dsk

[hatrick]

So I tried figuring out how to re-wire the handset from 4-wire to 3-wire based on the diagram you posted but I could never get a testable circuit (maybe because I have the two wires soldered together that attach to the phone).  Anyways, I was able to thread a wire through the handset and I tried every wiring combination I could from the two receiver terminals to the two transmitter terminals leaving the handset attached to the phone body and I could never get it to work where I could hear myself talking in the handset.  I'm not sure why when I look at the wiring diagram inside the lid it looks pretty simple where one wire goes from the receiver down to the transmitter and then to the phone and then a wire straight from the receiver to the phone and the third wire going from the transmitter straight to the phone.

Eric