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:
- Disassemble the case as described above.
- Using a low-wattage (50 W or less) soldering iron, unsolder the leads connected to the present cartridge.
- Bend the two cartridge-retaining tabs inward (toward cartridge).
- 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.
- Place the retaining ring and the O-ring on the replacement cartridge and slide the replacement cartridge into the chassis module.
- Bend the cartridge-retaining tabs outward (away from cartridge).
- Solder the leads to the cartridge terminals. See Figure 2 for proper lead connections.
- Insert chassis module in case front and switch button in case back.
- Fasten case halves with previously removed screws.
INTERNAL WIRING DIAGRAM