Overview

This repair follows the Line Cord and 505A Plug repairs.

Current Problem

The results of the first and second plug-in of the phone revealed some issues with the ringer as it sounded more like a buzzing / vibrating sound in both the soft and loud settings than a ringing bell sound.

On This Page

• Starting Point
• Process of Repair
  • Looking for a Quick Fix
  • Rotating the Gong Around its Axis
  • Making Adjustments to M1A Ringer
    • Sequence of the M1A Ringer Repairs & Videos
• GLadstone's YouTube Channel
  • Spreadsheet of YouTube Video Information and Upload Links
• Related Resources
• Repair Road Map

• Looking for a Quick Fix
• Rotating the Gong Around its Axis
• Making Adjustments to M1A Ringer
  • Sequence of the M1A Ringer Repairs & Videos

Looking for a Quick Fix

For more details, see this related message/post on Classic Rotary Phone Forum.

• Started with cleaning all metal contacts with a scrap piece of card-stock paper.
• Followed by switching the socket type terminal assemblies between BK and GN in the four prong 505A plug.
• Followed by switching the black ringer wire from G to L1 on the 4010 B Network (as is suggested for people with modular phones who are not able to get it to ring at all).

None of these quick fixes made a difference in the sound quality of the ringer in either the soft or loud setting.

(Note that the black ringer wire has been put back on G on the 4010 B Network.)

Rotating the Gong Around its Axis

I then found the M1A BSP and posted it to the forum.

Member poplar1 confirmed that the distance between the clapper and gong may be the issue:

http://www.classicrotaryphones.com/forum/index.php?topic=12714.msg134046#msg134046

"Try loosening the gong, then turning it. The hole is off center, so when you turn the gong, it will increase or decrease the distance between the clapper and the gong.

The biasing spring has 2 notches; you might try the other notch.

2.04 The 61A gong is eccentric. Clearance between gong and clapper shall be 0.010 to 0.020 inch. Resonator is built-in and needs no adjusting.

2.05 Bias spring is factory set in the high notch. It can be repositioned, as required, to either high or low notch with long-nose pliers.

BSP C18.048 issue 1, Oct. 1962"

Unfortunately, rotating the gong did not alter the clearance distance significantly enough to make much difference in the vibrating / buzzing sound quality of the ringer.

Making Adjustments to M1A Ringer

The following steps contain short video clips and have been separated on different pages to more easily review the repair changes and compare the ringer sound differences by opening in different browser tabs / windows.

Sequence of the M1A Ringer Repairs & Videos

With notes about repairs attempted and resulting ringer sounds.

1. Before Adjustments
   1. Repair Notes: Gong is at its closest point to the clapper.
   2. Video Notes: Phone ringing from second phone plug-in. Ringer vibrates / buzzes more than rings.
2. After First Adjustment
   1. Repair Notes: Adjusted clapper in a way that is probably not recommended.
   2. Video Notes: Loud ring sounds better, but I'm unsure of soft setting.
3. After Second Adjustment
   1. Repair Notes: Bought feeler gauge to better measure gap and fine-tuned some more clapper adjustments that may not be recommended.
   2. Video Notes: Loud ring has more "bell" quality, but still unsure of soft setting.
4. After Bias Spring Adjustment
   1. Repair Notes: Adjusted bias spring to low tension position, then back to high tension position.
   2. Video Notes: Ringer has more vibration / "loose" sound in loud and soft setting.
5. After Third Adjustment
   1. Repair Notes: Searched through Classic Rotary Phone Forum Archives again and found a different technique to try (from member twocvbloke).
   2. Video Notes: Loud and soft setting sound similar to After Second Adjustment.

Spreadsheet of YouTube Video Information and Upload Links

Related posts/messages on the Classic Rotary Phone Forum:

• First Plug-In, Part 2, aka Ringer Issues (with video)
• Ringer Update (cleaned, exchanged BK and GN 505A plug sockets, moved Black ringer wire)
• Move gong and/or bias spring- by poplar1

Related Bell System Practice (BSP) Documents:

• C18.048 I1 Oct62 - M1A N1A Ringer - Identification Maintenance Ocr R

Additional 702B BSPs are on the Resources page.

The project / repair links on this website can be found here (in order of repair):

1. Line Cord Repair
2. 505A Plug Repair
3. M1A Ringer Repair
   1. Before Adjustments
   2. After First Adjustment
   3. After Second Adjustment
   4. After Bias Spring Adjustment
   5. After Third Adjustment
4. Ringer Repair Videos