Seriss 82B Connection Block (REV-A)

A recreation of the Western Electric 82B connection block
Allows easy connection of 4A speakerphone system with 1A2 key phone sets that support speakerphone.

This Seriss 82b connection block board is a modern re-implementation of the Western Electric 82b connection block used to interconnect 4a speakerphone components with 1A2 key systems:
• 680A "Transmitter": Contains microphone, volume control, speakerphone on/off switch
• 108A "Loudspeaker": Contains amplifier, and relay circuitry
• 85B1 "Power Unit": an 18 VAC power supply for the above components

In place of an "Option Plug", the Seriss board uses a more conventional jumper block with an 8 position shunt to select between the two key system features:

• Ring Cut-Off - Option "A"
  This option cuts off the phone's ringer while the speakerphone is in use.
• Auxiliary Relay - Option "B"
  This option enables ringing during a speakerphone call, and causes a switch closure
  between KSU pins 25 and 50 while the speakerphone is in use, which can be used,
  for instance, to turn on a "Speakerphone In Use" lamp at a secretary's desk.

Here's a video showing how to set up and test a 4A speakerphone system with a 2565 using the Seriss 82B block:

Note that not all 1A2 key telephone sets support speakerphone. Some key sets lack the violet pairs on the station cable. This can usually be visually confirmed by looking at the phone's amphenol connector, and checking if the violet pair pins are missing.

Also, as described in the above video, some phones supporting speakerphone might have been modified by a previous installer to spare off the violet pairs (where they've been isolated and taped off) to support bridging. In such cases, to restore the phone for speakerphone use, you must move the violet pairs back to the factory defaults terminal screws. I've highlighted the violet pairs in these BSP schematics for the 2565HK/HKM and 2565GKMS model phones to aid in restoring their factory defaults (Click to view large schematics):

2565HK/HKM

2565GKMS

For more info on the 82b connection block, its options and its option screws, refer to: BSP 512-700-100 "4A Speakerphone System".

Also, for each telephone set that supports 4A speakerphones, there's usually a section that describes wiring considerations specific to that phone set, e.g. 565 and 2565 model sets: BSP 512-720-405 "565- and 2565 Set Connections / Speakerphone System 4A".

4A Speakerphone Components

• 680A - Transmitter




Known as "the transmitter", this small pedestal is both the microphone and pickup/hangup switch control for the speakerphone.

The left hand side labeled "ON" and "OFF" is basically a large rocker switch:

• Pressing "ON" will pickup whichever line is selected on the 1A2 phone set, allowing a call to be answered or initiated.
• Pressing "OFF" will hangup the call.
  Calls can be put on Hold in the usual way with the phone set's Hold button.
• Pressing "ON" while a speakerphone call is in progress mutes the microphone.

There is a volume control wheel which adjusts the speaker volume, and a lamp indicating when the speakerphone is turned on.





• 108A - Loud Speaker




This is the speaker part of the 4A system, and its volume is controlled by the dial on the separate 680A transmitter pedestal. The speaker contains most of the electronics for the speakerphone system and gets its power from the 82B1 power unit via the "AC" screws on the 82B connection block.

The 108B speaker has a cable with a partial amphenol connector that connects to the 82B block, giving it access to the selected phone line over the phone set's violet pairs, control signals from the 680A transmitter through the 82B connection block, and 18VAC power from the terminals on the connection block.

While the 4A speaker system is pretty good at preventing "feedback", it's still best to keep the 680A transmitter at least a foot or two away from the speaker to prevent feedback issues that can cause the unit to mute itself.





• 85B1 - 18VAC Power Unit




This AC power adapter provides 18 VAC to the 4A speakerphone system.

This connects to the 82B connection block's screw terminals labeled "AC", and provides power to both the 108B speaker's internal amplifier circuit and 680A transmitter's power switch and power lamp.

Schematic

The following schematic is similar to the original BSP documentation, but includes the JP1 jumper and its two option configurations, directly supporting the original option features provided by the Western Electric 82B's "Option Block". Also shown are the simplified circuits provided by these two options.

Seriss 82b Connection Block Schematic (REV-A)

PCB Design Files

This board layout was made in "Sprint Layout 6", a PCB layout program that generates gerbers and drill files that can be zipped together for upload to PCB fabrication companies for construction. JLCPCB and PCBWAY are two very good companies that will take the Gerber zip file and print the boards for you. You don't need the Sprint software to print the boards; that's only needed to make changes.

Here's the 82b (REV A) Sprint Layout file (.lay6), the Gerber (.gbr) and Drill (.drl) files in a zip, and a BOM Parts List. Note that the male amphenol, AMP1, needs two small slots machined by hand to accept the notched mini-amphenol connectors from the 108A speakerphone and 608A transmitter. Notching the connector is described below under the "Board Assembly" instructions.

All of the parts are usually available from Digikey. The amphenols can sometimes be in short supply, and can be ordered directly from the manufacturer, TE Connectivity. Solder-type amphenols can also be used in place of the press-fit type connectors.

All Layers - Top Silk/Copper/Mask, Bottom Copper, Outline, Drill
Top "Photo" - Top Copper, Silk, Mask, Outline, Drill	Bottom "Photo" - Bottom Copper, Silk, Mask, Outline, Drill
Top Copper, Mask, Outline, Drill	Bottom Copper, Mask, Outline, Drill

Board Assembly And Testing Procedure

Once the board is printed:
1. Prepare one of the two male amphenols for being slotted:
   
   
   
   • Line up the 108a and 680a connectors in the amphenol, and use a razor blade to mark the edges of the amphenol where the slots need to be made
   
   
   • Use a Hakko 2.4mm (3/32") nibbler / depaneling tool (available from amazon) to cut the two slots in the amphenol for the transmitter and speaker connectors.

     Hakko CHP DP-24-N Depaneling Tool	Nibbler slot cutting size
     Align nibbler with 2nd pin from each end to cut slots.	Amphenol with "nibbled" slot

   
   
   • Test the slot's alignment using the 108a and 680a connectors BEFORE press-fitting the amphenol
     (Once the amphenol is installed, the nibbler can no longer be used to make corrections!)
   
   
   
   


2. Press-fit the 3 amphenols: from left-to-right, Male / Female / Male.
   Be sure to get the connector orientation right — pin #1 is at the bottom on all 3 connectors.


3. Solder in the screw terminals for CN1 and CN2.


4. Install the jumper between screws "A1" and "2":
   
   


5. Install 8 position shunt on JP1 position "A":
   
   


6. Q/C test:
   
   
   
   1. Attach 85B1 power supply to the 82b block's "AC" terminal screws
   
   
   2. Connect the KSU to the 82b block's "KSU" amphenol connector:
      
      
   
   
   3. Connect the 2565 phone to the 82b block's "PHONE" amphenol connector:
      
      
   
   
   4. Attach 680A transmitter to the bottom of the 82b block's "SPKR/XMTR" connector (labeled "680 XMTR"):
      
      
   
   
   5. Attach 108A speaker plug to the top of the 82b block's "SPKR/XMTR" connector (labeled "108 LOUDSPEAKER"):
      
      
   
   
   6. Plug in the 85B1 power supply into an AC wall socket
   
   
   7. Select Line #1 on 2565, hit "ON" on the transmitter, check for dialtone in speaker
   
   
   8. Make test call to Line #2, verify transmitter microphone OK
   
   
   9. Clear lines, hit "OFF"
   
   
   10. Test Ring Cut-Off feature: hit "ON" for Line #1, trigger ringing on Line #2, verify no ring