Western Electric 500 - Rotatone v1 Install

[MrVestek]

Hi all,

First time caller, long time listener.

I've had a Rotatone v1 sitting in a drawer for years and finally decided that while I have some time off during this year's Christmas period that I'd install it into my Western Electric 500.

I've run into a few issues though and I'm wondering if somebody here can be of some assistance.

I have a zener diode in the kit and I know that I have to install it between RR and F but I'm not sure which direction I'm supposed to install it in. Not sure which is supposed to be anode and which is supposed to be cathode.

I'm not educated enough on schematics so I can't read the diagrams in a way that makes this obvious to me.

I've tried it in both directions though and I've... kinda gotten the Rotatone working.

I've connected all of the contact points in the correct places and sometimes the Rotatone will output a proper DTMF tone and sometimes it'll just introduce random noise into the line.

Anybody know this may me or what I may have done wrong?

It's driving me up the wall as I really want this to work.

[Dave Moll]

I don't suppose you have a circuit/wiring diagram of your telephone available, do you? That should provide a starting point for working out how to wire in the Rotatone.

[MrVestek]

The wiring diagram is available here:

I've rewired it to work on my phone system correctly though.

https://www.telephonecollectors.info...g-diagram/file

The black wire from the telephone chord (US standard) is wired to L2 to ring the bell correctly for instance.

I have connected the Rotatone to the phone correctly according to the instructions so I'm not worried about that...

It's just... the Rotatone that seems to be acting up.

I've stripped back wires and soldered them together to make sure that everything is connected together correctly and like I say sometimes the Rotatone will function as expected... but then at other times it will just introduce odd noise onto the line... like as if it's not playing back the DTMF tone correctly.

Or it plays back in a way where it sounds very far and distant.

[radiotechnician]

I am not familiar with your DTMF device.

However, WE 500 telephones have been part of my past.

A phone such as that will work on a line without respect to
the polarity of the incoming two wires, as long as the ringer
is connected across the line, and is matched to a capacitor
tuned to the proper frequency.

Ringer aside, the phone line has a polarity. The 500 set will
work either way.

You mentioned a zener diode. The anode and cathode
must be connected such that the rated voltage will
appear across it. If the connection is reversed, the
voltage will drop to a nominal value, usually 0.6 volt.


For experimenting with the hookups, a multimeter in series
with your phone will show two things. The nominal line current
from the telco switch, and the polarity of the current. It should
be constant for any phone you are using.

If your zener diode is hooked up such that the DTMF works,
the 500 set should behave as any other phone.

However it it works sometimes, and not others, the line
current and/or the polarity may have changed downstream
from your telephone connection point.

Good hunting..

We who collect and concern ourselves with old phones sometimes
use the instrument shown. It is a Radio Shack telephone analyzer.

(Cant be helped. Father was a telephone man)

[Dave Moll]

The Rotatone kit includes a bridge rectifier to ensure that its electronics, including the zener, receive the correct polarity regardless of the polarity of the incoming line voltage.

Two other thought have occurred to me regarding a Rotatone that sometimes works (which it will presumably only do with the zener correct) and sometimes doesn't. The first is that the Rotatone, running on much lower currents than are normally passing through the contacts of a dial, is very sensitive to any oxidation or other contamination on the dial contacts. I found with mine that I had several goes at cleaning the contacts before achieving reliable results.

The other, given the reports of DTMF tones sometimes being replaced by random noises, is whether the line voltage is on the low side, so that the Rotatone is not always receiving sufficient juice to work properly.

[MrVestek]

I suppose it couldn't hurt to try the bridge rectifier.

I figured that considering I'm connecting it up to a Virgin Media Superhub which has (what I assume is) VOIP functionality that I wouldn't need to worry about the polarity.

I'll give it a go though to see if it helps.

Ohh also, I know that I'm supposed to connect the zener diode across RR and F terminals on the network... but does anybody know in which direction it's supposed to go?

[Graham G3ZVT]

Originally Posted by MrVestek

I figured that considering I'm connecting it up to a Virgin Media Superhub which has (what I assume is) VOIP functionality that I wouldn't need to worry about the polarity.

My understanding is that VM only enable the FXS ports on the Superhub when used on their Fibre to the Premises offering, which is a small minority of their customers.

The polarity issue of the Rototone still applies.