Troubleshooting PTT Ericsson 1951

[Telephoner123]

I'm new at this and thought a good place to start would be a PTT model 1951 that I inherited from my grandfather.  It has a lot of static and the bell won't ring for incoming calls.  It doesn't have any obvious problems inside.  I tested the wires in the wall cord with a multimeter and they ranged from 6-11 ohms.  I don't know if that's OK.  The cord to the handset looked OK so I didn't bother testing those.  I also cleaned some of the contacts and hit the handset a few times to loosen the carbon (as recommended in another post).  But none of this helped.  The other posts I saw for this phone were too technical for me.

Any suggestions? 

[Matilo Telephones]

Hi there, congratulations on your Ericsson type 1951.

It does not ring, probably because you need to make a connection/bridge between the EW terminal (yellow) and A.

Which one those are, depends on which version you have. They come in 2 different configurations, with regards to the terminals.

It should be either 9 yellow (EW) and 10 blue (A) ir 10 blue (A) and 11 yellow.

Is there diagram inside?

[LarryInMichigan]

My experience is that most of the transmitter capsules in those phones are noisy.  No amount of banging or tapping on them helps.  What may help is connecting a resistor (anywhere between 300 and 800Ω in parallel with the transmitter to shunt some of the current away from it.  I have had to do this on many European phones because their transmitters cannot handle the amount of current which flows through them when connected to my phone line.

Larry

[LarryInMichigan]

BTW, most of those Dutch phones from the 1950s and 60s in North America were imported in the 1970s by Tandy and sold by Radio Shack stores.  They are quite common here.

Larry

[unbeldi]

My experience is that most of the transmitter capsules in those phones are noisy.  No amount of banging or tapping on them helps.  What may help is connecting a resistor (anywhere between 300 and 800Ω in parallel with the transmitter to shunt some of the current away from it.  I have had to do this on many European phones because their transmitters cannot handle the amount of current which flows through them when connected to my phone line.

Larry

How large is the current on your phone line?   I am not disputing the noisiness, but I am wondering whether it really has to do with current magnitude.  You can just short your line with an ammeter set to the 100mA range or so larger to measure it.

By my observation static on European phones often comes from the cords more often than the transmitter unit, but is certainly subject to accurate or insufficient tracking of statistics.

[LarryInMichigan]

The majority of my European phones had noisy transmitters.  Quite a few were weak.  Shunt resistors helped on some of the noisy ones.

Larry

[Telephoner123]

It does not ring, probably because you need to make a connection/bridge between the EW terminal (yellow) and A.

Is there diagram inside?

Yes, there is a diagram inside.  I'll take a closer look.  When you say a bridge, do you mean simply a wire going from one terminal to the other?

[Telephoner123]

My experience is that most of the transmitter capsules in those phones are noisy.  No amount of banging or tapping on them helps.  What may help is connecting a resistor (anywhere between 300 and 800Ω in parallel with the transmitter to shunt some of the current away from it.

Is the capsule the sealed thing in the part that goes against your ear?  Would the resistor go in the handset?  or the main part of the phone?  I wasn't able to remove the capsule.

[unbeldi]

It does not ring, probably because you need to make a connection/bridge between the EW terminal (yellow) and A.

Is there diagram inside?

Yes, there is a diagram inside.  I'll take a closer look.  When you say a bridge, do you mean simply a wire going from one terminal to the other?

Yes, that's what he meant.

Be sure to look at your diagram to verify terminals,  according to my experience and diagrams, the bridge should be between EW and B, which are terminals #11 and 10.

[unbeldi]

My experience is that most of the transmitter capsules in those phones are noisy.  No amount of banging or tapping on them helps.  What may help is connecting a resistor (anywhere between 300 and 800Ω in parallel with the transmitter to shunt some of the current away from it.

Is the capsule the sealed thing in the part that goes against your ear?  Would the resistor go in the handset?  or the main part of the phone?  I wasn't able to remove the capsule.

The transmitter is the microphone, the capsule that you speak into.

[Matilo Telephones]

It does not ring, probably because you need to make a connection/bridge between the EW terminal (yellow) and A.

Is there diagram inside?

Yes, there is a diagram inside.  I'll take a closer look.  When you say a bridge, do you mean simply a wire going from one terminal to the other?

Yes, that's what he meant.

Be sure to look at your diagram to verify terminals,  according to my experience and diagrams, the bridge should be between EW and B, which are terminals #11 and 10.

It does not ring, probably because you need to make a connection/bridge between the EW terminal (yellow) and A.

Is there diagram inside?

Yes, there is a diagram inside.  I'll take a closer look.  When you say a bridge, do you mean simply a wire going from one terminal to the other?

Yes, that's what he meant.

Be sure to look at your diagram to verify terminals,  according to my experience and diagrams, the bridge should be between EW and B, which are terminals #11 and 10.

There are 2 versions, with a different order to the A, B and EW terminals. I will post the diagrams.

[Matilo Telephones]

Here are the diagrams.

[dsk]

Hi, and welcome!
It is always difficult to know at what level we should  star on when a new member comes in, My limitations are among others, limited English. I am not so good at making my phones look good enough, but I.m pretty good on solving problems, and making them working, sometimes by modifying, or making/using new parts.

I start this at a modest level, please tell if it is to easy, or if you want more specific details.

The ringer should work after connecting the 2 terminals 9-10 or 10-11 with a metallic wire.  (You have to test what your model you have)
Nothing may go wrong if you test the wrong alternative.

The transmitter or microphone capsule are under the mouthpiece cap.  The schematic tells me this is a transmitter with pretty small granulates, and may not easily be replaced by a capsule from e.g. a Western electric telephone who usually has higher quality transmitters. (no reason to not try if you have one)  Transmitters from Berman, Belgian , Dutch, or Italian +++ phones may often have equal data. Some European door telephone transmitters may also do the job.  Where has this (your grandfathers) phone been used?

dsk

[Jack Aman]

What about electronic transmitters to replace the carbon grain microphones?  I have several, a couple a guy in Illinois made for me, and one I ordered from England.  They improve the outgoing voice performance of my 302's and 202's DRAMATICALLY.  Does anyone else here use them?

[dsk]

Yes many of them really makes the old phone work with modern sound, and may be the best way to get the family happy when using your old phones.  Many here seems to think it is a bad idea to put in electronics, but it is only a capsule easy to put back the original... if you keep it.  The circuitry of the phone in this thread may need to operate at extra low voltage, so may be difficult to find the right one.
German Ebay may come up with several if you search for: Sprechkapsel
(ebay.de)
some other links: http://www.elt24.de/shop/STR-80540-Mikrofon-fuer-Tuerstation-MK-1-
http://tinyurl.com/ml85tyw


dsk