Low volume on input of M-AUDIO Fast Track C400

[kagandary]

Hi everyone, hope you are doing well in these covid-19 days. I'm new in this forum.

Today, my audio interface Fast Track C400 gave me seizures. I bought it second hand months earlier. it has 2 channel, 4 input but the owner said that one input of the second channel is broken, and it was okay for me.

I used the device for days, but afterwards the second channel's inputs (3rd and 4th) stopped working. There was a big amount of noise and i cant even hear the instrument. i ignored it actually, and thought that it would not matter because i wasnt even using second channel but today, something strange happened.

i was using the interface for only listening like a week, today i tried to record something on my guitar in first channel (perfectly working one) but i couldnt even hear anything. both inputs (1st and 2nd) have the same issue. when i turn the input volume all up, there was a little sound, but it was really quiet. i checked to pad button again and again.

i tried to connect dynamic microphone too, which works perfectly fine but it has the same issue too...

i didnt dropped it, so it would not broke and i really dont know how did i make it stop working and how i fix.

probably there is bunch of grammer mistakes on that text im really sorry about that, but im really stressed, even my hands shaking right now.

i would appreciate if you guys help me.

thanks

[Drew Stephenson]

Hi Kagandary, there are a few things to check first.
Which input to channel 1 are you using? The instrument input on the front or the combi socket on the rear? And have you got the right input selected?
How are you listening to the signal? Headphones or speakers? And have you got the right option selected there?
When you've got something plugged in is the level meter on the top lighting up with the signal?

[kagandary]

Hi Kagandary, there are a few things to check first.
Which input to channel 1 are you using? The instrument input on the front or the combi socket on the rear? And have you got the right input selected?
How are you listening to the signal? Headphones or speakers? And have you got the right option selected there?
When you've got something plugged in is the level meter on the top lighting up with the signal?

Guitar connection is on the front left input and somehow, my sound card works "sometimes".
Yes, pretty weird.
For first 10 min, the interface works good ( i mean, the left inputs) but after 10 mins, the input signal drops. i experienced this a few times, even i didnt unplug anything, it randomly gets low input.
Im using it with headphones, and im sure that either my guitar and headphones is not broken, they works properly.
I really don't know what to do.. And sorry for late answers, i was working to my final exams..

[Drew Stephenson]

Ok, so when you first plug in and it's working ok, are you getting a good level on the meters on the top of the unit?
When the level drops, do these meters also show a reduced level or are they still good?

[Wonks]

I'd first suspect some broken or dry joints for the Jack connector contacts to the main PCB.

Do you know enough to take it apart and look for poor solder joints and repair them if necessary?

It may also be poor connections in the input selector switch, so a spray of contact cleaner in the switches once it's apart may help.