WWI 1917 Field Telephone Ringer Problems

[dsk]

The theory is quite easy, to describe it for real is not that easy.
I made a quick sketch.  If this doesn't work (the polarity of the components does not matter) we have start measuring, but now you have a meter.  

Measuring ohms across the receiver could give anything between 30 and 130 ohms.
across the receiver the readings may wary depending on position and movement, we often states normal readings to be between 50 and 200 ohms, but it could actually vary much more, but you should get a reading.

If the carbon granulate has clogged up, the transmitter will not work. Since the diaphragm may be fragile the only safe way to loosen this up is to make movements, or knock in the same direction as the forces would have been rolling it on an uneven surface.

dsk

[hatrick]

Hopefully I got this correct... I disconnected the 4-wire handset from the phone and connected the yellow wire to one side of my 6v battery pack (4-AA Batteries) and the green wire to the other side of the battery pack.  The red wire is already soldered to the second receiver wire.  After connecting things this way, I can hear myself talking through the handset although it is not very strong and certainly not as loud as the 3-wire handset (maybe there is some type of amplifier in the phone which is obviously not being utilized when wired this way).  So this is a step in the right direction (I think). 

Is there any chance that I soldered the wrong wires together when joining the red and receiver wires or would the polarity not be an issue here?

Thanks,
Eric

[dsk]

Yes you are doing it all right!  
It is no amplifier, so it may be a transmitter who need a treatment, or in worst case, a replacement.

Polarity is no issue here, before you put the wires back, it would be nice to know if the yellow really goes to the receiver, and the green really gos to the transmitter. (visually or by testing)

Then you may put it back according to diagram.

In offhook position you should read at a few volts dc between G and R and nothing between R and Y.

It just should work.

dsk

[hatrick]

Before soldering the one wire from the receiver to the red wire from the transmitter, I did verify both the transmitter and receiver wires so I think those are all ok.

I hooked the handset back up to the phone as previously instructed and powered up the phone with the 3 c-cell batteries and took reading with the handset off hook and on hook (the readings were the same) and using my new multimeter, I took readings from the heads of the Y, R & G handset wire screws and here is what I got.

With the red (+) on Y and the black (-) on R I got 4.5v
With the black (-) on Y and the red (+) on R I got -4.5v

With the red (+) on R and the black (-) on G I got 0v
With the black (-) on R and the red (+) on G I got 0v

With the red (+) on Y and the black (-) on G I got 4.5v
With the black (-) on Y and the red (+) on G I got -4.5v

Not sure what this all means since the numbers were not what you thought they would be but it does like like I am getting a full 4.5v from the batteries.

Thanks,
Eric

[dsk]

You are right, more or less opposite of what I expected.
If you cant hear yourselves at all, try to swap wires:  Y and G. I'm not sure about this, but it is no risk in trying.

dsk

[hatrick]

I tried swapping the Y and G wires but that didn't do it. 

Boy... this is really a head scratcher.

Eric

[dsk]

We have to be careful now, not to risk something like this:

[dsk]

I have been thinking: The error is in the handset/cord assembly. Not thinking about other possibilities.

If I understand you right, you are so lucky to have one working telephone too. Then you may lend handset/cord and test on the other telephone.

If the telephone works now, the error is in the handset/cord assembly.
If not, at least we don't have to concentrate around the handset, except if it is an error there + another.

If the OK telephone works, (with weak sound) with the 4 wire handset, we know the 4 wire handset = OK.

If not, we have to do some systematic testing, and put up tables with test results.

dsk

[hatrick]

Now that the holidays are well behind us it is time to get back to this darn phone.  I will take the ohm readings in the next couple of days based on your chart.  On your chart it says "Battery screw terminals shorted and measured 0 Ohms" - does this mean that I should short out the battery terminals with a jumper wire while taking all of these readings or that after taking the battery out, I  should just have a 0 ohm reading on the battery terminals before taking the readings? I figured I had better check before taking the readings.

Thanks,
Eric

[dsk]

Start with the testing by swapping handsets.
If it works OK with the known OK handset, we have just have to work on the handset.

If the not working handset works on the other phone, we know the handset is OK

If nothing works after swapping handsets, we deal with more than one error.

After this mount back the known well working telephone as you want it.


Before starting the measuring on the defect phone:
1: Remove batteries.
2: Remove handset
3: Strap (short) battery terminals.

You are now ready for measuring.

dsk

[dsk]

The unit with buzzer may be this one?
http://w1tp.com/im9000.htm

dsk