Remove the three No. 6 Phillips head screws securing the case assembly. Separate the case halves, remove the switch button, and remove the case front from the chassis module.

Model R98B Cartridge

The R98B is a replacement microphone cartridge for the 577B microphone. To replace the present cartridge with the R98:

  1. Disassemble the case as described above.
  2. Using a low-wattage (50 W or less) soldering iron, unsolder the leads connected to the present cartridge.
  3. Bend the two cartridge-retaining tabs inward (toward cartridge).
  4. Slide the cartridge out of the chassis module, remove the retaining ring from around the screen, and remove the O-ring from the rear of the cartridge.
  5. Place the retaining ring and the O-ring on the replacement cartridge and slide the replacement cartridge into the chassis module.
  6. Bend the cartridge-retaining tabs outward (away from cartridge).
  7. Solder the leads to the cartridge terminals. See Figure 2 for proper lead connections.
  8. Insert chassis module in case front and switch button in case back.
  9. Fasten case halves with previously removed screws.