Author Topic: Troublesome Western Electric Space saver  (Read 412 times)

Offline poplar1

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Re: Troublesome Western Electric Space saver
« Reply #15 on: February 24, 2018, 01:07:34 PM »
If you have an extra 500 (or 425 network) lying around, you could use it to better understand the 500-type circuit.

Input (telephone line) to network = RR and C
(The line can be connected directly to RR and C, or you can use L1 and L2 (blind terminals) then strap L1 to RR and L2 to C.)

Output =

GN = Receiver. (White)

B =  Transmitter. (Black)

R=  Common transmitter and receiver (Red for F1 handset OR Red and White for G1)

Now, if connected this way, the line would be "off-hook" all the time.
So if you have used the straps to connect L1 to RR and L2 to C, then removing either ONE of these straps will disconnect the line.

The dial also opens the line, for example 7 times if you dial a 7.

So, if you have a manual (non-dial) phone, you would replace one of the straps with two wires going to the hookswitch. Thus you would now have 7 wires from the 425 network = 2 (input) for the line + 3 (output) for the handset + 2 for the hookswitch.

If we add the dial pulsing circuit (Y and BK on a 5H dial), we can simply insert it in series with the hookswitch, so that hanging up or dialing will open the circuit.

In Jeff's diagram, notice that we leave the strap from L2 to C, but we remove the strap from L1 to RR and replace it with a strap from L1 to F. Then there are 2 wires from F and RR to the phone. When the phone is off-hook and the dial is at rest,  then there is continuity -- through Y and BK of the hookswitch, through the jumper wire from BK on hookswitch to Y on dial, through the normally closed dial pulsing contacts to BK on dial, then from BK on dial to RR on network.

Thus when off-hook and with the dial idle, there is a path from L1 to RR and L2 to C.

The black and red handset wires still go to B and R on the network.

Although the phone would still work with the white receiver wire going to GN on the network, there would be a loud pop in the receiver when hanging up, and clicks in the receiver whenever the dial was outpulsing. So, the receiver can be wired in series with the other hookswitch contacts (GN and W), and the dial BB and W contacts. When the phone is off-hook and the dial at rest, there will be continuity from GN on the network, to GN on the hookswitch, through the GN and W hookswitch contacts, through the jumper from W on hookswitch to BB on dial, through the normally closed BB and W dial contacts, then through the white handset cord to W in handset to receiver. Thus, there is continuity from GN on network to W in handset.

Note that when the 211 or 202 is used with a 500-type network/set/network type (685A)subset, the transmitter (black) is completely isolated from the switches (dial pulse and hookswitch).

When a 211 or 202 is used with an anti-sidetone subset (684, 634, or base of a 302), 4 wires are used between the phone and the subset, and black handset wire is on BK of the dial.

If you obtain a 202 or a 211 with F1 or E1 handset, it will usually have the black handset wire on BK of the dial. All you have to do is remove that black wire and connect it (using a new 5th conductor) to B on the network. Also remove the red jumper to R on the dial (211), or move the 2 red wires (in a 202) from R on the dial to the unused R terminal on the right.

« Last Edit: February 24, 2018, 01:21:03 PM by poplar1 »
"C'est pas une restauration, c'est une rénovation."--François Martin.