Classic Rotary Phones Forum

Telephone Identification, Repair & Restoration => Telephone Troubleshooting and Repair => Topic started by: easytiger on July 11, 2010, 07:59:12 PM

Title: Weird additional capacitor/condensor(?) & gong muffler(?) in non-ringing 302...
Post by: easytiger on July 11, 2010, 07:59:12 PM
Hi there - new to the forum.  I opened a non-ringing 302 I've had for years today to take a look, and found an odd  large vacuum-tube looking thing attached to the top of the condenser cannister.  It has a cardboard-roll cover around it.  "Defected BUTTER Fly Spring" is written in pencil on the cardboard.  It appears to be plastic, with Western Electric 372A printed/stamped on the end of it.  There are 3 wires coming from it attached to the L2, K, and GND terminals.  From what I can tell, there are only 2 wires coming out of the old cannister (instead of 4?), one going to the dial and the other going to the C Terminal.  The red ringer lead wasn't attached, but attaching it in all the usual places doesn't seem to make a difference.  Any idea what this thing is!?  Also, one of the gongs has what I assume to be some kind of "muffler" inside it.  It's stamped 101A on the top.  Never seen that before either.   In connecting the red ringer lead to L2 and moving the black wire from K to GND, the ringer does work a little, but with interference on the line.   Anybody have any ideas about any of this? 
Title: Re: Weird additional capacitor/condensor(?) & gong muffler(?) in non-ringing 302...
Post by: JorgeAmely on July 11, 2010, 09:21:42 PM
... Any idea what this thing is!? ...

... Also, one of the gongs has what I assume to be some kind of "muffler" inside it.... It's stamped 101A on the top. 

Welcome to the forum EasyTiger:

The first item is a low pressure neon tube used long time ago to aid in ringing phones that were connected in party lines.  It is essentially a DC controlled switch. It is no longer used and it is safe to disconnect all leads from the tube and rewire the set per schematics found at the TCI library. You should keep it inside the phone because it is part of the history of the set. Some people here (me included) have removed the paint coating and connected it so you can see the neon gas flash inside.

The second item is a gong resonator, used to enhance the sound produced by the gong. Perhaps your set was used many years ago by someone that was hard of hearing or the set was used in a busy office.

Title: Re: Weird additional capacitor/condensor(?) & gong muffler(?) in non-ringing 302...
Post by: easytiger on July 11, 2010, 09:44:41 PM
Thanks for the welcome and the information.  Interesting stuff.  I'll give it a whirl.  If my suspicion's are correct about only two wires coming from the original condenser canister (is the canister a condenser or capacitor!?), any idea if that will create issues with re-enabling a working ringer?  Also, I can't wait to hear a 302 ring with a resonator, but if it registers on the local Richter Scale, how does one remove the resonator without damaging it (or the gong or ringer?)
Title: Re: Weird additional capacitor/condensor(?) & gong muffler(?) in non-ringing 302...
Post by: JorgeAmely on July 11, 2010, 09:58:23 PM
I think the capacitor has 4 wires coming out of it: two for the ringer and two for the network connections.

I have attached a couple of pictures that illustrates how the set should be wired. Notice the slight modification to the schematic shown in the picture. This is because decades ago these sets required a grounded terminal to operate. That is not the case anymore.


Title: Re: Weird additional capacitor/condensor(?) & gong muffler(?) in non-ringing 302...
Post by: easytiger on July 11, 2010, 10:22:05 PM
Thanks, Jorge.  I removed the retaining bracket on the capacitor for a closer look and, indeed, this one has only two wires coming out:  1 Red and 1 Black.  The black leads to the BK terminal on the 5H dial, and the Red to the C Terminal on the network.  I'm used to seeing 4 as well - I don't see any wire-ends that appear to have been cut, so maybe it's been altered, or otherwise damaged or something - or specially wired/configured for some non-standard purpose.  The set works well other than the ringer (although, it hasn't been used MUCH on my watch).  I'm not sure of the ramifications of it having only two capacitor wires - or whether the ringer is a lost cause because of that.
Title: Re: Weird additional capacitor/condensor(?) & gong muffler(?) in non-ringing 302...
Post by: JorgeAmely on July 11, 2010, 11:00:13 PM
Can you take a picture of the inside of your phone? I have looked in two places and so far I haven't seen a 302 with a capacitor with only one pair of leads.

A light bulb just went on!  :o :o :o On phones with a tube, it is not really necessary to have a ringing capacitor in addition to the tube. That means that with some wiring modifications AND if the tube is still good (most of them are, so far I haven't seen a bad one yet), it should be possible to get your phone ringing again. However, that will make your phone polarity sensitive, since the tube is like a diode and wants to be biased in a certain manner.
Title: Re: Weird additional capacitor/condensor(?) & gong muffler(?) in non-ringing 302...
Post by: LarryInMichigan on July 11, 2010, 11:13:56 PM
You could always buy a .47 μF (non-polarized) capacitor at Radio Shack and place it in series with the ringer.  They cost about $1.49.

Larry
Title: Re: Weird additional capacitor/condensor(?) & gong muffler(?) in non-ringing 302...
Post by: easytiger on July 11, 2010, 11:35:48 PM
Here's some pictures...hopefully, they don't make it worse...I'm missing the photography gene.  You may have to send out a search party with the discussion about polarity...because I'm completely lost.    I appreciate any additional information, ideas, or direction you may have.  

What would it mean to have a set that is "polarity sensitive"?

If you have it in you to provide additional "laymans" detail about how to modify the wiring utilizing the tube, and/or placing a RS .47 (non-polarized) capacitor in series with the ringer, I'd appreciate it!
Title: Re: Weird additional capacitor/condensor(?) & gong muffler(?) in non-ringing 302...
Post by: JorgeAmely on July 11, 2010, 11:55:58 PM
Thank you for the picture. According to Dennis, that is a 195C capacitor.

Don't worry about not knowing much about polarity and stuff like that. No one is born with intelligence (except for crying and asking for food from Mom). Polarity has to do with the way electrons flow in a wire. It is the same principle that applies when you put batteries in a flashlight or when you replace the battery in your car. You don't want to reverse the polarity in your car because a lot of things will go bad (I have been there, believe me).

In older phones, polarity is not a big problem because phones can work with either polarity. The phone company sends -48 volts to your home to operate your phones. They arrive to your home as a pair of conductors labeled L1 and L2. L1 is close to ground (or zero volts) and L2 is -48 volts DC. When you introduce the tube, the tube has to be biased or exposed to voltages in a certain manner to operate correctly. What that will do to your phone is that when you plug it (and you use the tube as part of the ringing circuit) you have to make sure that L2 is more negative than L1, otherwise the ringer won't work. You can use it to place calls, but it won't ring.

I will modify a circuit diagram tomorrow and send it to you so you can wire it either way. It is getting kind of late here in the West coast and I have to get up early in the morning.
Title: Re: Weird additional capacitor/condensor(?) & gong muffler(?) in non-ringing 302...
Post by: easytiger on July 12, 2010, 12:22:26 AM
10-4, I appreciate it, Jorge. 

Interesting note:  When I opened the phone, the Red wire from the mounting cord was connected to the L2 terminal, and the Green to L1 (opposite of the standard diagrams, I think).  My lack of polarity knowledge notwithstanding, I did switch those in my trial-and-error routine...with no difference.

I have a handful of 302's and dug this one out to open to use as a guide for pesky issue I was having with another I've been using.  Imagine my surprise at the foreign terrain I found.

Thanks again...
Title: Re: Weird additional capacitor/condensor(?) & gong muffler(?) in non-ringing 302...
Post by: Phonesrfun on July 12, 2010, 12:56:18 AM
Hi Easy Tiger, welcome to the forum:

A rotary dial telephone is purely non-polarity sensitive.  There was a time when keeping track of the red and green was important to get the proper party line to ring.  Such would have been the case in your 306, which uses the cold cathode vacuum tube to achieve ringing based on line polarity.  Now, it is not important on a rotary dial phone at all.

One item of note:

Coming from the central office, the line and its associated polarities are referred to Tip (+) and Ring (-)  "Tip and Ring" is a holdover terminology from the old days and refers to the physical part of a switchboard plug to which the lines were terminated.

Tip (+) is usually going to be the green wire, and Ring (-) is going to be the red wire.  On the Western Electric sets, up to and inclucing the 300 series phones, red was connected to L1 on the phone and green was connected to L2. 

When Ma Bell came out with the 500, they decided to do a switcheroo inside the phone.  They decided to hook the green wire to L1 and the red wire to L2.

Nobody has been able to explain to me why this was done.

Again, polarity is unimportant with a rotary dial phone.  Touch tone phones which use electronic oscillators to generate the tones are very much polarity sensitive.  Later issues of touch tone phones that came out after the breakup of Ma Bell had a foolproof polarity guard built into the phone so that any dummy that bought a phone at the phone store could just plug and play.  Often we see people buying an old pre-breakup touchtone on e-bay and they can't get it to dial until they do reverse the polarity.


Title: Re: Weird additional capacitor/condensor(?) & gong muffler(?) in non-ringing 302...
Post by: HarrySmith on July 12, 2010, 07:25:55 AM
Welcome Easy Tiger. You will find plenty of nice helpful people here with much knowledge to share. I do not have anything to add to what has been said, I myself posted a question about gongs not long ago after seeing a phone on EBay with a pair that had the inserts. It is on here somewhere, lots of good answers on that one. I had the polarity issue also with an old trimline and got 17 simultaneous replies to switch the line wires after I said I could not dial! I want to get a 302 with that tube in it, very cool :)
Title: Re: Weird additional capacitor/condensor(?) & gong muffler(?) in non-ringing 302...
Post by: JorgeAmely on July 12, 2010, 10:48:23 PM
EasyTiger:

Here are some notes on how to rewire your 302 for ringing with either a ringing capacitor (polarity independent phone) or using the tube already in your 302 (polarity dependent installation).

#1 is a diagram showing both options.

#2 shows where terminal K is located. Leave your thick yellow wire at the ground connection. It is not used on modern phone lines.

#3 If you decide to leave the outside coating on the tube on, this is what you will miss: one side of the tube flickers at 20 Hz when a call arrives.

I created a Picasa photo album about these tubes a couple of years ago. Although mostly dedicated to the 426A tube, there are some pictures with the type of tube you have. Let us know your progress.

http://picasaweb.google.com/Amelyenator/WesternElectric501PhoneWithA426ATube#

PS: The two adjacent circles in option one represent the ringer.


Title: Re: Weird additional capacitor/condensor(?) & gong muffler(?) in non-ringing 302...
Post by: easytiger on July 12, 2010, 11:48:41 PM
I gave option 2 with the tube a try...and <drumroll> ...success!  Thanks a ton - would you blush if I said you were a genius?

I'm fairly brave, but in trial-and-error mode, I would have never arrived at that configuration - connecting two wires from the tube to the same (K) terminal.

I appreciate the time and help - for a lightweight, finding the right information in posts or linked/referenced documents, etc. can be like trying to get a drink of water from a firehose.

I appreciate the information from others in the post and references to the 306's as well.  That's another thing I wouldn't have known to even search for. 
Title: Re: Weird additional capacitor/condensor(?) & gong muffler(?) in non-ringing 302...
Post by: JorgeAmely on July 13, 2010, 12:08:14 AM
EasyTiger:

Only the clever Western Electric engineer that came up with a method of stringing many phones together on a single pair of copper wires and ringing them independently can be called a genius.

If you want more information about the tube in your phone, check out the Western Electric website:

http://www.westernelectric.com/spec_sheets/372A.pdf

Nowadays, they make super high end vacuum tubes for music systems. I'll love to hear one of those play.  :o :o :o

Title: Re: Weird additional capacitor/condensor(?) & gong muffler(?) in non-ringing 302...
Post by: cdc1960 on December 29, 2011, 12:36:30 AM
Just wanted to post a thank you to JorgeAmely for his hand drawn wiring diagram in this thread. I had been fighting with a 306 for several hours that I had just restored as it would not ring. This was the answer! Great forum, many thanks.

Regards,

Chris
Title: Re: Weird additional capacitor/condensor(?) & gong muffler(?) in non-ringing 302...
Post by: rtp129495 on January 09, 2012, 05:06:29 PM
THANKS for this POST!! i used to love vaccum tubes(still do but thought they all glowed hot), I never realized they had a glowing one for the 306, 302 etc......

I just ordered one on ebay they had a 426A listed, hope it works and i can wire it into a translucent 2500 i have!!! i think thats so awesome!!!!!