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-   -   Wiring Diagram For A 1970's Phone (http://www.diychatroom.com/f47/wiring-diagram-1970s-phone-27406/)

bobo 09-26-2008 11:39 PM

Wiring Diagram For A 1970's Phone
 
hello,

i hope i posted this question to the right forum!

i just aquired an old 1970's rototary desk phone. it has a switch on the housing of the phone, that i found out is for switching from one line to another. the green and red wires (tip and ring) are for one line, and the yellow and black (spares) are for the other line. i wired it for red and green and then yellow and black and both lines work. the problem is, the ringer is very weak. the bell clapper barley moves. these phones are usually bullet proof, so i dont think the coil for the ringer is bad, but could be. does anyone have a diagram for the internal network for this type of phone? i think the ringer may be wired to the network block in the phone wrong.

bob

DangerMouse 09-27-2008 07:23 AM

those old dialers usually had a 'ring volume adjust' tab/slider on the bottom. this may be the problem....but what do i know? i'm just a cartoon mouse......

DM

bobo 09-27-2008 09:55 AM

dm,

yes it does have a ringer adjustment. i have it on loud, and it is adjustnig the bells far apart like it should. im going to hard wire the bell to tip and ring on the customer interface and have someone call me and see if it rings....bob

rjniles 09-27-2008 10:43 AM

Quote:

Originally Posted by bobo (Post 161599)
dm,

yes it does have a ringer adjustment. i have it on loud, and it is adjustnig the bells far apart like it should. im going to hard wire the bell to tip and ring on the customer interface and have someone call me and see if it rings....bob


Hard wiring the ringer across the line will not work. The ringer coil will short cicuit the line and it will be busy to the caller. The network in the phone has a capacitor that is in series with the ringer that allows the AC ringing current into the ringer coil but blocks DC.

Between the the 2 ringer gongs is a mechanical adjustment wire that has 2 notches. It adds tension to the clapper arm. Try moving it to the other notch.

rjniles 09-27-2008 12:33 PM

If the phone in question is a Western Electric 500 series phone here is a link (other manufacturers used basically the same circuit)

http://www.porticus.org/bell/images/500dm.gif

Ringer coil 1 between BK and S-R

Ringer coil 2 between S and R

Capacitor (part of network) between A and K

BK and R ringer leads connected across L1 and L2 (Tip and Ring)

Wildie 09-27-2008 09:21 PM

It could also be that the capacitor has dried out and changed value.
Ringing voltage is 20 cycles per second, so the capacitance and the inductance of the ringer coils must be such, to allow the ringing current to flow.


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