Western Electric 302--- dial tone issues

[Adam]

Hi all!

This might be a long shot... but here goes.

I have an old, 1941 Western Electric Model 302 Telephone. This is a
'real' phone, and has always continued to work flawlessly... until....

We took the phone apart to clean and polish the case, and install new
cords. I had to remove the dial and the hookswitch. New cords (cloth
wrapped of course!) were installed and everything was put back together
exactly as it was.

We have a wiring diagram for it, everything is in the correct place.
Here are its symptoms:
1. When listening with the phone off the hook, you can hear the line
noise, but no dial tone
2. slight motion of the pulse dial gives a momentary dialtone, which
then disappears
3. the phone rings properly, but will not answer when lifted off the hook.

The wiring diagram from Western Electric indicates that one of the two
clapper switches in the hook switch assembly "makes last" but it does
not give any specifications-- should there be a delay between the
closure of one part and then the other? I can't really imagine the phone
company in 1941 detecting an 80ms delay between two switches?

I've really been at wits end because nothing seems to have changed
except that the phone wont trigger a dial tone. My previous
understanding was that the CO (central office) detected a closed circuit
through the hook switch and that was what triggered the dial tone. I've
checked all contacts in both the hook switch and dial and they all
connect and disconnect cleanly.

Any suggestions, interest, or help would be grately appreciated!

Thanks again!
-Adam
[email protected]

 

[Bob Shuman]

Adam,

Any chance you reversed the tip and ring connections when you did the
re-furbishing? The reason I ask is that the phone ringing signifies both
leads are making contact, but since the ringing voltage is AC, polarity does
not matter. This may not be true for the on/off hook (I'm not familiar with
that old of a vintage of phone...) since it uses the -48VDC and that circuit
may have an internal diode which would prevent the Telco office from sensing
the current and sending the dial tone.

Good luck and post your results.

Bob

 

[Ken Weitzel]

Hi all!

This might be a long shot... but here goes.

I have an old, 1941 Western Electric Model 302 Telephone. This is a
'real' phone, and has always continued to work flawlessly... until....

We took the phone apart to clean and polish the case, and install new
cords. I had to remove the dial and the hookswitch. New cords (cloth
wrapped of course!) were installed and everything was put back together
exactly as it was.

We have a wiring diagram for it, everything is in the correct place.
Here are its symptoms:
1. When listening with the phone off the hook, you can hear the line
noise, but no dial tone
2. slight motion of the pulse dial gives a momentary dialtone, which
then disappears
3. the phone rings properly, but will not answer when lifted off the hook.

The wiring diagram from Western Electric indicates that one of the two
clapper switches in the hook switch assembly "makes last" but it does
not give any specifications-- should there be a delay between the
closure of one part and then the other? I can't really imagine the phone
company in 1941 detecting an 80ms delay between two switches?

I've really been at wits end because nothing seems to have changed
except that the phone wont trigger a dial tone. My previous
understanding was that the CO (central office) detected a closed circuit
through the hook switch and that was what triggered the dial tone. I've
checked all contacts in both the hook switch and dial and they all
connect and disconnect cleanly.

Any suggestions, interest, or help would be grately appreciated!

Hi Adam...

The telco detects a load on the line through the hook switch, but not
a dead short I think you're going to find that the load is made
up of both the reciever and the transmitter. Seeing you hear noise
and intermittently dial tone, I'd double and triple check the
transmitter. Both in the handset, if you can get to it, and of
course the wiring.

The delay between the two switches opening is merely to ensure that
the phone doesn't ring in your ear

Take care.

Ken

 

[[email protected]]

I have an old, 1941 Western Electric Model 302 Telephone. [...]

I've got a couple of 1950s and 1960s 500 sets. One thing I've noticed
is that these sets, if the line cord is original, have three wires -
red, green, and yellow. Red and green are ring and tip and yellow was
originally ground. If you don't hook up the yellow, sometimes these
sets don't work. If I remember right, connecting the yellow to the
green wire makes it work.

I don't know if the older dials have this same problem, but you might
look at http://www.repairfaq.org/REPAIR/F_audiofaqd.html#AUDIOFAQD_003 .

Is it possible that one of the internal wires has broken inside the
insulation? An ohm meter will tell you pretty quickly.

You might dig around on this site:
http://www.bellsystemmemorial.com/telephones-olderthan500.html . If the
info doesn't help, I think there are links there to people that fix old
phones.

If you can't think of anything else, find out where your local phone
exchange is. Go there around noon when the linemen are sitting in their
trucks, eating lunch. Find the oldest one and trade beer or whatever
for phone repair services.

Matt Roberds

 

[Sam Goldwasser]

Hi all!

This might be a long shot... but here goes.

I have an old, 1941 Western Electric Model 302 Telephone. This is a
'real' phone, and has always continued to work flawlessly... until....

We took the phone apart to clean and polish the case, and install new
cords. I had to remove the dial and the hookswitch. New cords (cloth
wrapped of course!) were installed and everything was put back
together exactly as it was.

We have a wiring diagram for it, everything is in the correct
place. Here are its symptoms:
1. When listening with the phone off the hook, you can hear the line
noise, but no dial tone
2. slight motion of the pulse dial gives a momentary dialtone, which
then disappears
3. the phone rings properly, but will not answer when lifted off the hook.

The wiring diagram from Western Electric indicates that one of the two
clapper switches in the hook switch assembly "makes last" but it does
not give any specifications-- should there be a delay between the
closure of one part and then the other? I can't really imagine the
phone company in 1941 detecting an 80ms delay between two switches?

I've really been at wits end because nothing seems to have changed
except that the phone wont trigger a dial tone. My previous
understanding was that the CO (central office) detected a closed
circuit through the hook switch and that was what triggered the dial
tone. I've checked all contacts in both the hook switch and dial and
they all connect and disconnect cleanly.

Does the resistance into the phone go low when it's off-hook?

--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
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Important: Anything sent to the email address in the message header above is
ignored unless my full name is included in the subject line. Or, you can
contact me via the Feedback Form in the FAQs.

 

[jakdedert]

Does the resistance into the phone go low when it's off-hook?

--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
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Just working from memory--distant memory--and referring to symptom #2
above, it sounds like the issue may be in the dial mechanism. Given
that the dial makes/breaks the line connection in order to function, and
further given that a dial tone can be obtained, however briefly, by
moving it...it seems to me to be a contact issue within the dial itself.

I could be wrong, but....

jK

 

[Sam Goldwasser]

Just working from memory--distant memory--and referring to symptom #2
above, it sounds like the issue may be in the dial mechanism. Given
that the dial makes/breaks the line connection in order to function,
and further given that a dial tone can be obtained, however briefly,
by moving it...it seems to me to be a contact issue within the dial
itself.

Probably two wires are swapped.

Perhaps double check the wire colors if that's what you're going by.

--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above is
ignored unless my full name is included in the subject line. Or, you can
contact me via the Feedback Form in the FAQs.

 

[[email protected]]

They didn't have diodes in 1941 of the kind you are thinking about

H. R. Hofmann

 

[[email protected]]

They didn't have diodes in 1941 of the kind you are thinking about

H. R. Hofmann

 

[Ken Weitzel]

They didn't have diodes in 1941 of the kind you are thinking about

H. R. Hofmann

Hi...

I stand ready to be corrected, but to the best of my recollection
there were none at all - save mercury vapor tubes...

Had to carry the radio battery down to the corner gas station to
have it recharged once in a while... until Rogers invented the
rogers batteryless radio

Matter of fact if any history buffs are out there, that resulted in
a radio station in Toronto - CFRB, where the RB is Rogers Batteryless.

And today that station still continues, as well as all of the offshoot
Rogers stuff; like Rogers Cable, and Rogers cell network, etc.

Ken

 

[Michael Black]

Hi...

I stand ready to be corrected, but to the best of my recollection
there were none at all - save mercury vapor tubes...

What year did selenium rectifiers come into use?

Though I can't remember the name, I thought there was also some
other non-tube diode that was in use.

There's little reason to expect either in a phone from that vintage,
but that doesn't mean there weren't such things.

Michael

 

[Ken Weitzel]

What year did selenium rectifiers come into use?

Though I can't remember the name, I thought there was also some
other non-tube diode that was in use.

There's little reason to expect either in a phone from that vintage,
but that doesn't mean there weren't such things.

Hi Michael...

Got my old memories going again... googled everywhere I could
think of and can't find any reference to any rectifer pre-dating
selenium.

Gee, speaking of memories... anyone else remember the odor of one
of those selenium plate rectifiers when the load was shorted?

Yikes.

Your telephone... dunno if my message on the subject got lost in
cyberspace, but still think you should check the transmitter and
wiring.

An experiment? Plug it into a jack that's part of your house system
Leave it on hook; get someone else to pick up another phone and make
a call to a friend. As soon as they're connected and talking, you
pick up your handset - see if you can hear and talk to them.

Take care.

Ken

 

[Stan]

}Hi all!
}
}This might be a long shot... but here goes.
}
}I have an old, 1941 Western Electric Model 302 Telephone. This is a
}'real' phone, and has always continued to work flawlessly... until....
}
}We took the phone apart to clean and polish the case,

(snip-pity doo-dah)

Please measure ohms across wires to CO 1) on-hook and 2) off-hook and
report back.

Stan.

 

[Bob Shuman]

Suggest you measure current flow instead using a small resistor as there
will be nominal -48VDC (-52VDC @ high battery) across the tip and ring
terminals which will blow out most ohm meters.

Bob

 

[Asimov]

"Michael Black" bravely wrote to "All" (12 Oct 05 03:15:47)
--- on the heady topic of "Re: Western Electric 302--- dial tone issues"

MB> From: [email protected] (Michael Black)
MB> Xref: core-easynews sci.electronics.repair:344872

Hi...

I stand ready to be corrected, but to the best of my recollection
there were none at all - save mercury vapor tubes...

MB> What year did selenium rectifiers come into use?

MB> Though I can't remember the name, I thought there was also some
MB> other non-tube diode that was in use.

MB> There's little reason to expect either in a phone from that vintage,
MB> but that doesn't mean there weren't such things.


Michael,

I think there were all kinds of metal/metal-oxide rectifiers in those
early times. They weren't very good but that's all they had. Selenium
was just a more evolved type.

A*s*i*m*o*v

.... Thomas Edison invented the "Light Emitting Resistor"

 

[Bill Janssen]

Hi Michael...

Got my old memories going again... googled everywhere I could
think of and can't find any reference to any rectifer pre-dating
selenium.

Try googling for Copper Oxide rectifier. It was used in a A battery
eliminator
my Dad had in the 1930's

Then there were aluminum "wet" rectifiers used to get the high voltage DC
for some Ham transmitters.

Bill K7NOM

 

[Michael Black]

"Michael Black" bravely wrote to "All" (12 Oct 05 03:15:47)
--- on the heady topic of "Re: Western Electric 302--- dial tone issues"

MB> From: [email protected] (Michael Black)
MB> Xref: core-easynews sci.electronics.repair:344872



MB> What year did selenium rectifiers come into use?

MB> Though I can't remember the name, I thought there was also some
MB> other non-tube diode that was in use.

MB> There's little reason to expect either in a phone from that vintage,
MB> but that doesn't mean there weren't such things.


Michael,

I think there were all kinds of metal/metal-oxide rectifiers in those
early times. They weren't very good but that's all they had. Selenium
was just a more evolved type.

Yes, it was metal-oxide rectifiers that I was thinking of but couldn't
remember the name.

Michael

 

[Fred McKenzie]

I have an old, 1941 Western Electric Model 302 Telephone. This is a
'real' phone, and has always continued to work flawlessly... until....

We took the phone apart

Adam-

The responses to your question appear to contain all the information you
need to find the source of your problem, but scattered among them!

Basically, the phone presents a relatively low resistance across the phone
line when the hook-switch closes. Reacting to the resulting current, a
current-sensing relay at the central office closes, and a dial tone is
sent back down the line.

The telephone's dial is also connected across the phone line. When you
dial, a short circuit is intermittently connected across the line to
generate a number of higher-current pulses corresponding to the number
dialed. In your case, the current caused by dialing activates the
current-sensing relay, which had NOT been previously activated by the hook
switch.

Using an Ohmmeter in conjunction with the diagram, you should be able to
troubleshoot the problem. As someone mentioned, you must disconnect the
phone first, because the 48 Volts DC from the phone company might damage
your meter!

Someone mentioned a third wire that had to be connected to get a phone to
work. Modern telephones use two wires to connect to the phone company,
but early phones had a third wire used for party lines. In addition to
using different ringing frequencies to signal individual parties on the
line, the phone company also could apply the ringing voltage from one side
of the line to ground, the other side of the line to ground, as well as
line-to-line as is done today. If such a third wire were not connected,
the ringer would not work but calls could be made.

Fred

 

[Bob Shuman]

Lastly, the ground is the + side of the 48VDC. I share this here since the
bias on the phone lines was -48VDC (below earth ground) to help prevent
corrosion of the copper wires.

Another thing I seem to recall is that the scan "off hook" current requires
approximately 20mA.

Bob

The responses to your question appear to contain all the information you
need to find the source of your problem, but scattered among them!

Basically, the phone presents a relatively low resistance across the phone
line when the hook-switch closes. Reacting to the resulting current, a
current-sensing relay at the central office closes, and a dial tone is
sent back down the line.

The telephone's dial is also connected across the phone line. When you
dial, a short circuit is intermittently connected across the line to
generate a number of higher-current pulses corresponding to the number
dialed. In your case, the current caused by dialing activates the
current-sensing relay, which had NOT been previously activated by the hook
switch.

 

[Don Bowey]

Adam-

The responses to your question appear to contain all the information you
need to find the source of your problem, but scattered among them!

Basically, the phone presents a relatively low resistance across the phone
line when the hook-switch closes. Reacting to the resulting current, a
current-sensing relay at the central office closes, and a dial tone is
sent back down the line.

The telephone's dial is also connected across the phone line. When you
dial, a short circuit is intermittently connected across the line to
generate a number of higher-current pulses corresponding to the number
dialed. In your case, the current caused by dialing activates the
current-sensing relay, which had NOT been previously activated by the hook
switch.

Good discussion, but one small correction: When you dial, the dial contacts
open the current path and then close the path for each pulse. During the
time that set of contacts is open, another set is closed, shorting out the
earpiece so there is no click in the ear. The CO reads each pulsed
open-interval. When the string of (one to ten) open pulses completes, the
current path is simply maintained by the closed dial contacts.

Using an Ohmmeter in conjunction with the diagram, you should be able to
troubleshoot the problem. As someone mentioned, you must disconnect the
phone first, because the 48 Volts DC from the phone company might damage
your meter!

Several people have asked the OP to measure the DC resistance of the phone
while it is off-hook and NOT connected to the line. I don't believe he has
responded.