Northern Telecom LOGIC 10/20/30 Phone Sets

[erco]

To connect a Northern Telecom NT LOGIC 10 phone set to the Seriss KSU, there are some requirements:

• You must have REV-J1 (or higher) of the Seriss KSU. Older revisions do not support this phone properly
  
• It is advised you have a WE (Western Electric) style cable [SEE NOTE 1]
• To wire the buzzer, use the wiring shown below. If you don't want to use the buzzer, leave the KSU's Y-O pair unconnected
  

WARNING

Do not directly connect an NT LOGIC 10 phone to the older revision KSUs, it can immediately blow the cartridge fuse because it shorts the supply via the Y-O pair.

NOTE 1:

NT LOGIC phones came with two optional cable types: NT (Nortel) style, or WE (Western Electric) style.

WE style cables are 1A2 compatible, and what the documentation below shows.
For an NT style cable, many more signals have to be rewired to work properly; see the NT LOGIC 10 phone's documentation.

Proper Wiring for NT LOGIC 10/20/30 to a Seriss KSU

Use a 66 block (or 66E3) to properly change the signal wiring for the Seriss KSU. In particular, do not bridge the Y-O pair directly from the KSU to the phone. The KSU's Y-O pair needs to be redirected to the buzzer pair, or if the phone has no buzzer, leave the Y-O pair N/C (Not Connected).

• On the 66 block, you can bridge all the lines 1-5 T/R/A/L signals straight across
  
  
• Also, you can bridge the Y-S pair (45 + 20) straight across for bell ringing.
  Verify the bell is actually wired inside the phone to the Y-S pair, and the ring capacitor is bypassed.
  
  
• Special wiring is needed for the KSU's Y-O pair (see Fig. 1 below)
  
      Wire the KSU Y-O (42) to phone's V-BR (49)
      Wire the KSU O-Y (17) to phone's V-G (48)
  
  Verify the buzzer is attached to the V-BR and V-G pair. On the phone used for testing, the buzzer
  is wired to the B7 and D7 positions on the terminal block inside the phone (Fig. 2 below)
  

That's it. If the buzzer is wired correctly, picking up Line 5 and dialing the phone's extension should buzz the buzzer.

Fig. 1

Fig. 2

Note that some phones have a different style terminal board, station cables (NE vs WE), and may have
unusual wiring for bell and buzzer. It is recommended that you:

• Wire the phone's bell to Y-S pair
• Bypass the ring capacitor, so that the Y-S pair goes directly to the bell
  
• Wire the phone's buzzer (if any) to the spare pair for 48 (V-G) and 49 (V-BR)
  

Please refer to the Northern Telecom LOGIC series documentation for more information.

If people with Seriss KSU's have any questions, you can follow up to this thread.

[erco]

On Thursday, August 20, 2020 at 6:47:28 PM UTC-7, erco wrote:

To connect a Northern Telecom NT LOGIC 10 phone set to the Seriss KSU [..]

    Here's a rough schematic of what I used, so you can see the complete path for the buzzer circuit, through all the connections including the phone's internal t-block, and for reference the Northern Telecom schematics for the phone itself.

[erco]

The support for NT LOGIC 10/20/30 phones is now in the revision j manual (in section 2.15 on page 12), showing the 66 block wiring and buzzer terminal locations inside the phone, necessary for proper buzzer operation.

These phones unfortunately don't have a full screw terminal block (that many of the WECO phones have) which allows more full control over wire assignments. So you need a full 66 block between the KSU and phone, using bridge clips to pass through the normal signals, and a pair of jumper wires to handle the small two wire reassignment.