1940 302 will not break tone

[Sargeguy]

I was working on my 1940 matching date 302 and remembered why such a prize was not in active rotation among my household phones.  I hooked up a modular cord to replace the absent line cord and... nothing.  I checked the receiver element and it was a dud so I replaced it with a known good one and...nothing.  I dialed my house number and it rang, but when I picked up the handset, it would not break tone.  I did a couple double-checks of the wiring, which it looks like I never tampered with except to remove the old cord, and everything is intact and where it should be.  The switch appears to open and close as normal.  Is there anything else I should check before I swap out the coil?

[unbeldi]

I was working on my 1940 matching date 302 and remembered why such a prize was not in active rotation among my household phones.  I hooked up a modular cord to replace the absent line cord and... nothing.  I checked the receiver element and it was a dud so I replaced it with a known good one and...nothing.  I dialed my house number and it rang, but when I picked up the handset, it would not break tone.  I did a couple double-checks of the wiring, which it looks like I never tampered with except to remove the old cord, and everything is intact and where it should be.  The switch appears to open and close as normal.  Is there anything else I should check before I swap out the coil?

There are some contradictions in your description.

The "receiver a dud" means you didn't hear anything?  And with the replacement you still heard "nothing"  How did you decide that it didn't break dial tone?  How did you listen to the dial tone when you heard "nothing"?

Listen to the dial tone on a second, good telephone connected to the same line and dial the trouble phone. You should hear the dial pulses.
If you do hear them, but not on the trouble phone, then it could still be that the dial switch BB-W is bad. It should be closed normally to connect the receiver, except during dialing.  You can place a short wire across those terminals to test this switch.

You know the ringer works apparently, so there is not a short across the telephone, between L1 and L2, which also means the dial switch R-BK is not shorted.

Swapping the coil seems like a drastic measure before you know what's wrong. You could be swapping every component before you find the problem.

If you do hear dial tone, not breaking dial tone means the exchange did not recognize dial pulse.  So either they don't get generated or not generated in an acceptable manner. So, very likely it is a dial issue.

Do you have an ohm meter?  measure the resistance across the coil windings.  L1-R (22 ohms), GN-C (19 ohms), GN-R (75 ohms).

[Sargeguy]

Sorry, I'm working on 3 different 302/251s at the same time.  

The 1940 has no tone and picking up the receiver does not break the ringing.  I would've thought the problem was in the switch but it appears to be operating normally.

[Sargeguy]

I finally figured out how to use a Multimeter and the values check out on the 101A

It's a #5 dated 1940.  Like I said, all dates match.  The phone is absolutely pristine inside and appears to have seen very little use.

I will post pics if I can get my iPad charged up

[tallguy58]

How'd you use the multi-meter? Please explain

[Sargeguy]

How'd you use the multi-meter? Please explain

I watched this video:

http://www.youtube.com/watch?v=BCd1nk1b5AY

I then set the value to 200 in the  Ω Ohms section

I placed each tip on the 101A in the spots unibeldi recommended and compared the readings to the expected values

[Sargeguy]

I am leaning towards the contacts being bad on the rotary,and I am assuming that everything else has been checked out

Lets see what spraying it with contact cleaner does

[Sargeguy]

Nothing.  Usually it's something obvious I missed.  Here are some pics:

[Sargeguy]

Hmm I didn't notice that oxidation before, could that be the culprit?

[poplar1]

Definitions:

"Can't break dial tone"=you have a dial tone when you pick up the receiver, but you cannot dial out--the dial tone is still there when the finger wheel returns to rest

"Trip ring"=when the phone is ringing and you go off-hook, it stops ringing

In other words, you never "break dial tone" when you *answer* any phone.

On a 302, temporarily moving white receiver wire from W on dial to GN on ind. coil bypasses  dial off-normal contacts and receiver contacts of switch hook.

On a 302, temporarily moving the black wire from BK of the dial to L2Y bypasses the switchhook  and dial contacts to check for dial tone.

On a 302, if the black handset wire is open, you can't "trip ring" when you pick up the handset if the phone is ringing; it will keep ringing. You also cannot "draw dial tone" when you go off-hook to originate a call.

[Sargeguy]

On a 302, if the black handset wire is open, you can't "trip ring" when you pick up the handset if the phone is ringing; it will keep ringing. You also cannot "draw dial tone" when you go off-hook to originate a call.

Bingo!

[poplar1]

Rather than replacing the receiver or even opening the set, you can also test for open xmtr this way: Just turn the finger wheel slightly and let go; you should then hear a burst of momentary dial tone.

With the black handset cord lead open, or the transmitter missing, or the transmitter contacts bent down too far, you have a "monitor" where you can hear dial tone if *another* phone goes off hook. You can also hear incoming ring through the receiver. This is similar to the "monitor" setting on a butt set (installer/repairman's test set) or a 107B speaker used to monitor the line.

[Sargeguy]

This phone is so nice I may have to keep it!!!