Hi all,
Thank you so much for your answers!
I am so sorry because I did not explain prepertly what I was doing/measuring.
I was injecting 1KHz/+4dBu signal to each channel for checking all of my channels. I measure the signal from each channel insert out with my NTI Minilyzer ML1 device (where 4dBu are drop at this point).
On 20 channels of my console y get measurements like: +0.01/+0.05/-0.02/-0.01... as I have defined as +-0.05dBu (all the measurements are betweeen -0.05dBu and +0.05dBu), the balance is correct in every channel and the signal frequency is detected correctly (1000Hz); so everything is fine.
There are 4 channels, where the balance and signal frecuency detection is correct but the measurements are these: +0.64dBu/+0.46dBu/-0.58dBu/-0.39dBu
I was asking if would be any trimmer or any way to fix this issue, I knew that the deviation was caused by the mother board, line pot or other thing, instead of the 82E149 card (because I swap the card between channels and the problem remained in the channel, so...)
Now, I know that the issue is regarded to the dirty line pot (thanks Chris). As I have mentioned, it is not a big issue for me, but I was not sure if there it was any way to trim the input signal as in the 82E291 card and as I try to learn everything about the console...
Thanks to all for answering, I will try aplying EML lube and try turning the pot several times in both directions. Maybe I would be able o reduce the deviation, but if not... does not matter.
Thanks to all once more.
Best regards.
Oihan