Merlin 3070 Service And Maintenance Manual page 179

Check system configuration.
3.
The following modules should be in the control unit and at least
partly functional for the diagnostics to be fully effective:
Power Module (must be fully functional)
Processor Module
Feature Module
Line Module in slot 7 (Line Modules
slots as well.)
at least 1 Voice Terminal Module or
Remove any other types of modules (except the Diagnostics
Module, if it is installed). Set the Power Module On/Off switch to
Off when removing a module.
4. Check backplane pins.
Check for bent or broken pins in the control unit backplane.
Damaged pins can cause incorrect fault indications or signals.
Contact your equipment supplier if you have any faulty pins.
Be sure each module is firmly seated in the control unit.
Install Diagnostics Module.
5.
If the Diagnostics Module is not already in place, set
Normal/Test switch on the module to Normal and slide the
module firmly into slot 4.
6.
If you are not using a data terminal, proceed with "Using the
Diagnostics Module Alone," page 5. If you are connecting a
terminal, proceed with "Using the Diagnostics Module with a
Data Terminal," page 7.
4
may be present in other
Basic Telephone Module.