AML ez1073 gain issues

[fritzmyname]

Hey y'all,

I just finished building my 500 series AML ez1073 kit and I'm currently calibrating and troubleshooting it.

First of all, I am wondering on how to calibrate it. I will have access to an oscilloscope tomorrow, so I have the tools, but I am still trying to figure out what kinda test signal I have to apply where. Any help is greatly appreciated.

Secondly, I noticed something strange: when looping a sine signal from reaper through the unit and recording/monitoring it back into my daw, I noticed that the 10 position is louder than 15. 10 has roughly the same volume as 35? From 15 to 65 the gain steps are equal. How would I go about testing/fixing that? When I had it hooked up loosely in the chassis (no screws, therefore moveable) and touched the gain knob (and while doing so making the grayhill switch touch the edge of the faceplate) the volume in the 10 position seemed normal (quieter than 15). As soon as I let go of the knob, it increased by about 10 dB or so.

The internal gain trim R70 pot doesn't seem to change the output volume. Calibrating R58 (90 mV) worked tho.

Thanks a lot in advance for any help!

Cheers

 

[TLRT]

If I remember well you have to insert 7.75mV to the input and set the gain to 60dB which is amplification value x1000, so at the output you should trim 7.75volts with the impedance setting 1200ohms.