Hi Folks
A customer has brought in a NAD C340 amp where none of the input selector buttons work or their corresponding leds.
I did read:
https://www.diyaudio.com/forums/solid-state/91538-nad-c340-input-selector.html
and also googled the problem.
This lead me to believe that the switching IC maybe faulty. I have replaced the switching IC and the problem persists.
I have tested the new IC. Pin 1 is ~16-17 V- and pin 28 is ~16-17 V+.
I have tested R.H. channel inputs(pins 18 to 27 of the I.C.) and get no voltage. I tried L.H. channel inputs on the other side of the IC and got the same result.
I think Q702 IC on the "Display PC Board (NADIS-6365)" is faulty. I have looked at the service manual and the input selector buttons do indeed first connect to Q702. Q702 then turns the button press into 128-bit or 256-bit serial data.
The datasheet for the switching IC (TC9273N) says: "The switches are set to ON or OFF using 128-bit or 256-bit serial data."
Is there a way to confirm which IC is faulty?
I think the new switching IC (TC9273N) is fine, because it is getting power; but its not doing anything because it's not being sent serial data by Q702.
A customer has brought in a NAD C340 amp where none of the input selector buttons work or their corresponding leds.
I did read:
https://www.diyaudio.com/forums/solid-state/91538-nad-c340-input-selector.html
and also googled the problem.
This lead me to believe that the switching IC maybe faulty. I have replaced the switching IC and the problem persists.
I have tested the new IC. Pin 1 is ~16-17 V- and pin 28 is ~16-17 V+.
I have tested R.H. channel inputs(pins 18 to 27 of the I.C.) and get no voltage. I tried L.H. channel inputs on the other side of the IC and got the same result.
I think Q702 IC on the "Display PC Board (NADIS-6365)" is faulty. I have looked at the service manual and the input selector buttons do indeed first connect to Q702. Q702 then turns the button press into 128-bit or 256-bit serial data.
The datasheet for the switching IC (TC9273N) says: "The switches are set to ON or OFF using 128-bit or 256-bit serial data."
Is there a way to confirm which IC is faulty?
I think the new switching IC (TC9273N) is fine, because it is getting power; but its not doing anything because it's not being sent serial data by Q702.