Selector Plugs and Shelf Jacks.
Each 2-motion selector is fitted with a 32 connexion point plug which engages with the shelf jack. The plug and jack terminals are commonly known as "U points" and are indicated on the relevant schematic diagrams by a small V
together with the jack point number placed on the lead concerned, e.g. jack point No. 20 is represented by V20.
The U points are so designated that the odd-numbered U points start from the centre of the shelf jack (as seen from the rear) and count outwards towards the right. The even-numbered U points similarly start from the centre, and count outwards towards the left. The following allocations are adopted wherever possible :
1. - 1,2ve (in). also connected to TJ3 & TJ5 }
from previous
2. + 1ve(in). also connected to TJ4 }
Selector
3. Ringing return earth.
4.- ve battery.
5.- ve (out).
6.+ 2ve (in). also connected to TJ6 drives WS relay wiper select
7. Private (out).
8. Dial tone.
9. P wire. also connected to TJ2 & TJ8( 9 and 11 make contact when the selector is removed)
10. C.S.H. or P.G. alarm.
11. Earth.
12.Battery.
13.Test trunk bell
14. Interrupted earth.
15. Release alarm earth. connected to TJ12
16. Busy tone earth. Fed to calling party via A relay
17. Flicker earth.
18. N.U. tone earth.
19. Ringing return battery. (paired 32?)
20. Positive Battery
21. As required.
22. As required.
23. Sleeve.
24. As required.
25. As required.
26. As required.
27. S pulse.
28. Interrupted battery and earth.
29. As required.
30. Ringing tone earth. Fed to calling party via A relay
31. Z pulse.
32. Interrupted ringing. (paired 19?) Fed to the called party via the F relay coil ( that detects answer)
32 30 28 26 24 22 20 18 16 14 12 10 8 6 4 2 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31Counting from the white line at the centre of the Selectors connector to the left it's 2, 4 ,6etc to 32 and to the right 1,3,5 etc to 31...contact 12 is Battery (ie-50 v dc) contact 11 is earth (ie 0 v dc).Incoming line is on 1 and 2, So looping 1 and 2 out to a loop dialling jellybone will allow you to dial into it. p wire is on 9
To power up the selector simply use two croc clips and some cardboard !