F-5 - Page 247

Confidential

9-59

F-5 

Speaker is silent during on-hook dialing. 

Possible cause 

Step 

Check 

Result 

Remedy 

Connection 
between main 
PCB and speaker 

1 

Main PCB and speaker 
are properly connected. 

No 

Fix the connection properly. 

Speaker 

2 

Replacement of speaker 
solves the problem. 

Yes  Replace the speaker with a 

normal part. 

Connection 
between main 
PCB and NCU 
PCB 

3 

Main PCB and NCU 
PCB are properly 
connected. 

No 

Fix the connection properly. 

Harness between 
main PCB and 
NCU PCB 

4 

Harness is damaged. 

Yes  Replace the harness with a 

normal part. 

Connection 
between main 
PCB and control 
panel PCB 

5 

Main PCB and control 
panel PCB are properly 
connected. 

No 

Fix the connection properly. 

Harness between 
main PCB and 
control panel PCB 

6 

Harness is damaged. 

Yes  Replace the harness with a 

normal part. 

NCU PCB 

7 

Replacement of NCU 
PCB solves the 
problem. 

Yes  Replace the NCU PCB with a 

normal part. 

Main PCB 

8 

Replacement of main 
PCB solves the 
problem. 

Yes  Replace the main PCB with a 

normal part. 

F-6 

Dialing function does not switch between "tone" and "pulse". 

Possible cause 

Step 

Check 

Result

Remedy 

Connection 
between main 
PCB and NCU 
PCB 

1 

Main PCB and NCU 
PCB are properly 
connected. 

No 

Fix the connection properly. 

Harness between 
main PCB and 
NCU PCB 

2 

Harness is damaged. 

Yes 

Replace the harness with a 
normal part. 

NCU PCB 

3 

Replacement of NCU 
PCB solves the 
problem. 

Yes 

Replace the NCU PCB with a 
normal part. 

Main PCB 

4 

Replacement of main 
PCB solves the 
problem. 

Yes 

Replace the main PCB with a 
normal part