Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!accuvax.nwu.edu!nucsrl!telecom-request From: "Barton F. Bruce" Newsgroups: comp.dcom.telecom Subject: Re: Help a Model 500 Ring Message-ID: <11567@accuvax.nwu.edu> Date: 31 Aug 90 01:34:37 GMT Sender: news@accuvax.nwu.edu Organization: Cambridge Computer Associates, Inc. Lines: 27 Approved: Telecom@eecs.nwu.edu X-Submissions-To: telecom@eecs.nwu.edu X-Administrivia-To: telecom-request@eecs.nwu.edu X-Telecom-Digest: Volume 10, Issue 610, Message 8 of 11 In article <11346@accuvax.nwu.edu>, jcox@x102a.harris-atd.com (Jamie Cox) writes: > I have an old desk top dial phone which works but does not ring. I > The ringer solenoid has four wires, red, white, red/white and black > > Red R/W Blk White > | | | | > \/\/\/\/\/\/ \/\/\/\/\/\/ > ~ 3k ohms ~ 1k ohms The BLACK and RED go to tip and ring (the green + red line cord wires) probably on (L2) and (L1). Polarity only matters if you get tappity-tapping from an extension rotary dialing or going on/off hook. There are also mechanical adjustments to eliminate tapping. The SLATE (white) and RED/SLATE go to (A) and (K) that are the 2 ends of a 1/2 mfd cap to block talk battery from the ringer coils. There is a lot of history behind those two different size windings, but the simple description is that they provided a second party id by connecting one of them between ground and the electrical midpoint of the transmission network (B) when a second party phone went off hook. The CO could determine which subscriber went off hook - the one with or the one without the connection to ground.