Guys,

Does anyone have a pin out or diagram for wiring a Northern Telecom Logic 20 set to a standard Bell System 551 KSU? I wired it up like a traditional 10 button phone with some weird results.

Thanks!

Scott

Lines 1 to 5 each use 3 pairs. That's pairs 1 to 15 white blue to Black slate.
Line 6 uses Y Bl for TR and YO for A lead and OY for lamp lead
Line 7 uses Y GR for TR and VB for A lead and BV for lamp lead
Line 8 uses V Or for TR and VG for A lead and GV for lamp lead
Line 9 uses VBr for TR and VS for A lead and SV for lamp lead

The VGr and VBr are spare pairs

The second strip of keys buttons 10 to 14 use 3 pairs each and Button 15 uses YBL for TR and YO for A and L
Button 16 uses YGr for TR and YBr for A and L
Button 17 uses YSl for TR and VBl for A and L
Button 18 uses VO for TR and VGr for A and L
Button 19 uses VBr for TR and VSl for A and L

There are no spares on the 2nd strip of buttons.

I'll look for a wiring diagram, but if i remember correctly, the first 5 lines wired the same (W/BL to BK/SL) and then it ran in order straight through. (Y/BL & Y/OR were line 6 with the Br/BK as the A lead and....)

I thought I remembered, it exactly, but I guess I don't. I'll have to go look.

Maybe one of our Northern neighbors will chime in earlier?

Marv, Dave - do you remember offhand?

Sam

I got a print here but I cant get it uploaded. So I found this for a Logic 10. The first strip of buttons is the same. I will try again tomorrow. Try looking under View

https://www.telephonecollectors.inf...0-key-telephone-sets-installation-manual

That's it.

As I recall, the sets were available two ways - with a 'standard' cord and with the alternate wiring cord.

Sam

Terribly sorry, I guess I missed the responses on this.

Thanks guys!!

Thanx Bob3740 for the logic 10 manual. I haven't seen one of those phones since the old Mitel SX20 installs of the early 1980s where they were the operator consoles.