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and very rarely ever needs repairs, once you fix them." - Dan/Panther

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Confusing phone wiring diagrams with possible solutions

Started by countryman, June 21, 2021, 02:18:39 PM

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There sure is more than one proper way to draw a wiring diagram.
Standards change over the decades, vary among the different companies, etc. Most styles make sense and after studying them for a moment, things become clear. But not anytime.
The most confusing diagram for me has been the German OB05 magneto phone for a while (first pic). It has got serious competition now from the Belgian RTT56 I received this week (second pic). It is bilingual, but the letters used for the color code do not correspond with either language. It is a dial phone, but where are the dial contacts. Come on... what am I missing? 
Which diagram published for a standard phone is your personal pet peeve?


Your dial  pulse contacts are across the .1uf capacator and the shunt contacts above that in the diagram


I like the challenge with such diagrams, but this one was definitly confusing, at least to understand why they have made the anti sidetone compesation circuit that complex.

I tried to redraw a simplified diagram of the circuit in off hook pos without dial and hook sw, with focus on the ind. coil, and even that ended pretty confusing.


Thanks for your help Dag!
I found a clearer diagram for the earlier ATEA model 50. The Ohm values are different, but it also has the 0.1µF cap across the pulse contacts. It's at least similar. It's on the collector's site


Close, but..
Not sure, but I believe this is right...  Find 5 errors or..  ;D


Wow, this is very helpful! It might be worth to move the thread to the diagram section...
Thanks again Dag!


I was in the business today with the RTT56 lot I had gotten recently. There seems to be no better diagram published for these frequent phones than the shown one. The ATEA50 is closely related in fact, as dsk pointed out, but uses different wire colors.
Of course the answer for my question on how to mount a dial was already on CRPF:
It shows the wire colors of both the A and B version!
While the ATEA50 has spade terminals where the dial cord goes to, the RTT56 has not. The dial cord is soldered to the underside of the terminal block, or 3 wires to be exact. The fourth (orange) goes to the earthing button (point P in the upper right of the diagram in my first post). Very confusing!
I used a U.S. AE dial which I had. It has the right size, while most European dials are a couple mm larger. The mounting holes do not match, but it could be mounted firmly with the existing hardware though. It's not correct, but looks and works just like the Antwerp ATEA dial of the RTT56A