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Using a 425 network from a 500 for older phones

Started by Phonesrfun, January 04, 2010, 04:19:08 AM

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Phonesrfun

This is kind of a rehash, but I have done my own independant research, and I agree with Benhucherson and Bingster on the use of the 425 series networks for the older 102,202,211 and candlestick phones.

Primarily, you want to have the network free from all hookswitch and dial connections.  It can have the ringer attached in its normal fashion.

I studied the schematics of the 500 series phones and also the easier to understand version that is in Ralph Meyer's book.  At first, I thought this was going to be impossible, given the totally different way the 425 network accomplishes switching, but it really isn't all that different once you think around the Bell System box.

Just as Benhutcherson has said in an earlier post, the connections are:

Line cord:
Red to L2
Green to L1  These are just as normal.

Ringer:
Black to L1
Red to L2
Slate to K
Slate-Red to A  These ringer connections are standard for the 500 too. (a)

If you have just a stand-alone 425 network without the ringer, the above ringer connections are not needed.

Desk set cord:

For a sidetone phone using a 3-conductor desk set cord like a 102, or a sidetone candlestick:
Red to R
Green to GN
Yellow to L2
Jumper L1 to RR on the network

For an antisidetone phone using a 4-conductor desk set cord like a 202, a 211 spacesaver, or an antisidetone candlestick:
Red to R
Green to GN
Yellow to L2
Jumper L1 to RR  on the network
(Did you notice that all these so far are exactly the same as the sidetone?)

Now for the extra black antisidetone feedback wire:

Ben said in his post to connect it to K.  This is where I differ.  I would connect it to C.

In testing this out, I am getting standard current through the circuit.  My Vonage service uses 24 volts instead of 48, so my current is lower at 25mA, but it is exactly the same for any phone I have connected.  Also, as it should be, there is no DC current present in the receiver circuit, which is critical, and just as it should be.

One other note.  You need to completely remove all wires from the hookswitch that is intergral to the base of the 500 phone.  Earlier models had wires soldered to some of the pads on the network, and we cannot have any of those hooked up and interfering, so they would need to be cut off if you are using an older phone.  These same older phones did not have a screw terminal on the C connection, so on those older 425 networks some way of connecting the black desk set wire needs to be provided onto the C terminal.

Again, I was very skeptical as to how this could be accomplished.

Benhutcherson and Bingster:

I would very much like to hear from the both of you (and anyone else) on this matter of using C as the antisidetone connection and any other information you may have.

Oh, and I almost forgot.  Since I am only using C as the antisidetone connection, the self-regulating varistor and resistor that are in the circuit between C and RR are not being used, so that defeats this use of the network as a self-regulating network, and kind of achieves the effect of turning this back into a 101A induction coil from that standpoint.

If one wants to keep the self regulating aspect, one can go to the extent of re-wiring the phone itself to put the switching and dialing into more of a 500-like configuration.  If I haven't bored anyone to tears by this time, anyone so interested can check out the re-configured 202 diagram using the 685A subset which uses the 425 network that Steph Kerman and Keelan Lightfoot have authored and is on the TCI website at:

http://telephonecollectors.org/library/weco/202-685x.pdf

The task of rewiring is simple enough, but requires the use of a 5th wire in the cord that goes from the phone to the subset.  This is similar to the work I did a few months ago on Dan's GPO candlestick.

So, someone, please comment.....

(a)  Note that when I say 500 series, this can include the networks in the Princess and other phones of the era too.  Undoubtedly this will also work with the AE80 network too, but I have not tried this yet.

-Bill Geurts
-Bill G

Dennis Markham

#1
Very nice work Bill!  I will give your method a try.

An offer to anyone that may want a 425B network.  I have a pile of rusted, nasty bases from 500's that will make good donor's for a network.  If anyone would like one or more send me a PM.  I'll post this offer in the Classified Section.

Here's the posting in the Classified Section:

http://www.classicrotaryphones.com/forum/index.php?topic=1959.msg26411#msg26411

benhutcherson

Bill,

Studying the schematic, I agree that "K" would be incorrect.

As a follow-up in Tom's post on his imperial, I stated to connect the black wire to "F". This was based off of an examination of the schematic, although I personally have not tried this combination.

I'll do some experimenting with this connection later today, and report back.

Thanks for your studying and write-up on this.

gbailey123

Hi, I have a Western Electric 51AL candlestick phone which has been rewired using a 425e network.  It wasn't ringing when I got it, so I stupidly re-wired it without taking a picture.  Now I don't get a dial tone.  Currently, it is connected as follows:

Line in:
Green to L1
Red to L2
Yellow to K

Ringer:
Red to A
Black to L1

Phone:
Red to R
Balck to B
gray to GN
Yellow to C
Green to L2

How should it be connected?  Any help is greatly appreciated.  Thanks!


Phonesrfun

GBailey:

Welcome to the forum!

First of all, you probably realize that the 425e network was not the original network, and so the phone has been re-wired for that.  In doing the rewire, the line cord wires that you have of Red, Black, Gray, Yellow, and Green could be wired to just about anything within the body of the candlestick.

In order to answer your question, we need to know where those 5 wires are connected within the candlestick.  Can you write those down and/or take some pictures to pass along?

That way we can help.

-Bill G

deedubya3800

Doesn't the black wire in the mounting cord go to B on the network?

Phonesrfun

-Bill G

deedubya3800

Good. There was some confusion over that earlier in this thread. :)

deedubya3800

I'm trying to do this with a 4228 network and a P3A ringer. So far, I can call out and everything sounds great both ways, but I absolutely can not get it to ring. This ringer type has four wires, but the slate and slate/red are usually capped off and not used. In its native environment, this ringer would hook up black to L1, red to K. Hooking it up as shown here or with just black to L1 and red to L2 causes the ringer to make a disturbing click, but not a ring. This ringer worked perfectly well in the phone it came from. Any suggestions?

Phonesrfun

The ringer needs a capacitor, which is what is between terminals A and K on the network

Connect the ringer black wire to L1, and the red ringer wire to K.  You then must have a jumper wire between A and L2 to complete the circuit.

With no jumper, there is no complete AC circuit.  Hooking the ringer directly across L1 and L2, with no capacitor in series creates a DC circuit which blocks the AC, and no ring-ee ding-ee.

-Bill G

deedubya3800

Thanks! I'll try that when I get hoam tonight. :)

deedubya3800