SC48 - Help with Noisy Input

[BD123123]

Hi,

We have an SC48 and it sounds like one of our inputs has gone "bad". Input 6 on the top card.
Patching this input to any channel/fader results in "noise". All other inputs are fine.

Can anyone help with understanding what might need replaced? Does the whole card (16 inputs) need replaced or can a specific input be fixed/replaced?
Or how do I go about finding the offending part - e.g. A/D convertor. Are there bits on the card can be swapped to identify the specific component at fault?

Unfortunately we are out of warranty.

I know Avid have a place in Dublin, Ireland. Does anyone know what services are available at that location? Do they do repairs, parts or service?

Thanks for any help.

[TheMAXX]

Did you change the cable that is feeding that input? I know this is basic but I have found that sometimes I get so close to looking at a problem that I make a very basic mistake. We had what we thought was a bad channel coming from a keyboard but it turned out that someone got into the keyboard settings and boosted some of the output channels and it was causing distortion on the outputs of the keyboard itself. I have also had a bunch of bad channels on a snake in an installed system that threw us off for a little bit.

If you plug a mic directly into the input does it still have the problem?

I think Avid has an exchange program where they send you a new part and you send them back the old one after you get the new part. I think that they charge you for the new one and refund some of that when they get the old one back.

[BD123123]

Originally Posted by TheMAXX

Did you change the cable that is feeding that input? I know this is basic but I have found that sometimes I get so close to looking at a problem that I make a very basic mistake. We had what we thought was a bad channel coming from a keyboard but it turned out that someone got into the keyboard settings and boosted some of the output channels and it was causing distortion on the outputs of the keyboard itself. I have also had a bunch of bad channels on a snake in an installed system that threw us off for a little bit.

If you plug a mic directly into the input does it still have the problem?

I think Avid has an exchange program where they send you a new part and you send them back the old one after you get the new part. I think that they charge you for the new one and refund some of that when they get the old one back.

Hi,

When I tested, I removed all connection from this input to the console. So there was noise with nothing plugged in to the rear.

[JamesLaverdure]

I am having this issue with one of my input cards. The second channel on the card gives off static noise with nothing plugged in. I have already purchased a replacement card and changed it out. The issue is completely gone. However, I'd like to see if it is possible to still fix this card and keep it as a backup. Any resolutions on this issue?

[JamesLaverdure]

Originally Posted by BD123123

Hi,

When I tested, I removed all connection from this input to the console. So there was noise with nothing plugged in to the rear.

Did you make any progress on this?

[BD123123]

Hi,
Unfortunately not. Still noisy so we just dont use that channel.
I did chat with Avid on it, but it all got too logistically complicated and was easiest just to not use the channel.

How easy was it to change the card?

[JamesLaverdure]

That's unfortunate that they didn't get anywhere with you on it.

Replacing the card is pretty easy though. There are 4 screws on the card itself. Then there are about 16 screws on the front plate that need to come off to access the ribbon cable to unplug it from the mother board. Once that front plate is off, you disconnect the fan cable and set that front plate aside. Slide the card out and slide one a new one in. Took me less than 30 minutes. Just don't lose any of the small screws as they will fall and they are hard to find in dark places.

[Greg C]

Originally Posted by BD123123

Hi,
Unfortunately not. Still noisy so we just dont use that channel.
I did chat with Avid on it, but it all got too logistically complicated and was easiest just to not use the channel.

I asked about this several years ago where I have a "hissy" input on one of my SC48 inputs. I was told that it was bad resistors on the input. They can be replaced with he proper surface mount soldering tools. But it's probably easier to just replace the card as they're not that expensive.

[PLew]

Hi, I came across this post and thought this might be helpful.

I just fixed that same symptom, I believe the board # is A116.
There 2x 10 ohm chip/surface mount resistors on the underside of the board near the input jack near/under the op-amp IC, and one of them was open.
I measured all the pairs across the inputs, and the rest were not measuring higher that 10 ohms. R0108 R0109 location.
But that's just for input #1, the numbers naturally will be different on other inputs

Measure with a multimeter first to be sure, in circuit they should measure 10 ohms.

They're tiny about the size of 1/2 a grain of rice (way smaller than a banana, which I hear is a measurement people use these days )
When you remove it, so you don't pull/wreck a path, heat up both sides til it moves, as there's a little glue under chip components.


I made a picture, but the forum doesn't seem to allow.