Author Topic: Can't figure this one out, guys!  (Read 1673 times)

Offline tallguy58

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Can't figure this one out, guys!
« on: September 16, 2014, 07:55:09 PM »
Continuing from this thread:

http://www.classicrotaryphones.com/forum/index.php?topic=12644.msg132781#msg132781

here's how the phone is wired now:

QNB425E1A network

Ringer:
black on G
red on L2
slate on K
slate/red on A

Handset:
white on R
white on GN
black on B
red on R

Hookswitch:
slate L2
slate/brown C
slate/red GN
slate/black on R
slate/white on F
slate/green on L1
slate/yellow on L2

Dial:
white on R
white on GN
blue on RR
green on F

Won't break dial tone when dialing.
Dial tested on another 500 and it works.

PS Thanks Poplar1 for the link to the wiring diagram.
« Last Edit: September 16, 2014, 08:00:15 PM by tallguy58 »
Cheers........Bill

Offline Kenton K

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Re: Can't figure this one out, guys!
« Reply #1 on: September 16, 2014, 08:09:08 PM »
Will it break dial tone if you tap the hookswitch?

-Ken

unbeldi

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Re: Can't figure this one out, guys!
« Reply #2 on: September 16, 2014, 08:13:47 PM »
Looks ok.
I am sure you know your ringer isn't connected to the line with black on G alone.

Can you hear the dial pulses from another telephone connected to the line?

Offline tallguy58

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Re: Can't figure this one out, guys!
« Reply #3 on: September 16, 2014, 08:25:17 PM »
Tapping the hookswitch makes the dial tone disappear.

Black ringer is to go on L1 right? (Green line in lead )
Cheers........Bill

Offline Phonesrfun

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Re: Can't figure this one out, guys!
« Reply #4 on: September 16, 2014, 08:43:05 PM »
Tapping the hookswitch makes the dial tone disappear.

Black ringer is to go on L1 right? (Green line in lead )

yes
-Bill G

Offline tallguy58

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Re: Can't figure this one out, guys!
« Reply #5 on: September 16, 2014, 08:48:37 PM »
Is the network pooched?
Cheers........Bill

unbeldi

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Re: Can't figure this one out, guys!
« Reply #6 on: September 16, 2014, 08:57:16 PM »
Can you hear dial pulses from another phone connected to the same line?


Next test would be to take both wires off from the F terminal but keep them connected to each other and test the telephone. This removes the dial pulse RF filter that is across the dial pulse contacts.

Offline tallguy58

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Re: Can't figure this one out, guys!
« Reply #7 on: September 16, 2014, 09:06:11 PM »
I had my wife dial the 151AL while I listened and I could hear the pulses.

Connecting the two F leads together off the network made the phone work properly.

Can I just connect them both to the L3 terminal which looks like it's free standing?
Cheers........Bill

unbeldi

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Re: Can't figure this one out, guys!
« Reply #8 on: September 16, 2014, 09:31:49 PM »
I had my wife dial the 151AL while I listened and I could hear the pulses.

Connecting the two F leads together off the network made the phone work properly.

Can I just connect them both to the L3 terminal which looks like it's free standing?

Yes, that would be permissible from a technical standpoint.
You simply don't have a working RF filter which is of somewhat academic utility these days. Most telephones before 1950 (the 500-sets) didn't have one either.

This would narrow the failure down to the filter capacitor.  If you have a multimeter you can test the capacitor by measuring the resistance between RR and F (nothing connected). Ideally it should be extremely high, blocking DC.

Ah... hmm, you dialed on the 151AL ?  you need to dial on the 500 and listen on the stick.

Offline tallguy58

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Re: Can't figure this one out, guys!
« Reply #9 on: September 16, 2014, 09:42:13 PM »
Reading is 0.

Cap looks like a Motorola 5231B. Man, it's tiny. 
Cheers........Bill

unbeldi

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Re: Can't figure this one out, guys!
« Reply #10 on: September 16, 2014, 09:58:54 PM »
Reading is 0.

Cap looks like a Motorola 5231B. Man, it's tiny.

Zero ohms?  that baby is shot.
It should block DC.

The value of the capacitor should be about 0.12 μF.  Together with the 180 ohm resistor it provides a cutoff frequency of about 9000 Hz, as a low-pass filter.

Motorala 5231B ?  Are you sure that isn't the varistor?  Are there two of them standing by the edge?
I think the capacitors for this network are in that plastic block, can't be exchanged.


« Last Edit: September 16, 2014, 10:01:41 PM by unbeldi »

Offline tallguy58

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Re: Can't figure this one out, guys!
« Reply #11 on: September 16, 2014, 10:16:55 PM »
That 5231 is soldered to those two contacts.
Cheers........Bill

unbeldi

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Re: Can't figure this one out, guys!
« Reply #12 on: September 16, 2014, 10:30:06 PM »
That 5231 is soldered to those two contacts.

The capacitor should not be soldered to both, the F and RR terminals. It should only be connected to the F terminal.   The other side of the capacitor goes to a resistor and to the varistor.  The other end of the resistor goes to RR, and the other side of the varistor goes to C eventually.

unbeldi

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Re: Can't figure this one out, guys!
« Reply #13 on: September 17, 2014, 10:27:46 AM »
Come to think of it only now...  I don't see how the resistance between F and RR can be zero.  It should at least be 180 ohms.

Here is the basic circuit of a 500D set.  I don't think the Northern Electric set would be that different. Perhaps there is something special about your network.  We examined another one of these recently and it seemed the same.

From the circuit you see what is between F and RR.  There is the filter capacitor and a resistor in series. If the cap is shorted, you get 180 ohms. If the resistor is burned it would be infinite; a resistor shorting is quite implausible.

Perhaps you're just happy that the set is working now, and that is fine.  I think we isolated the trouble.
« Last Edit: September 17, 2014, 10:30:21 AM by unbeldi »

Offline tallguy58

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Re: Can't figure this one out, guys!
« Reply #14 on: September 17, 2014, 06:47:16 PM »
And I thank you.

You always have great solutions to these problems. Very well explained.

 8) 8)
Cheers........Bill