[mungu]

Hi all -

I just finished my first MP573 and so far it has gone pretty smoothly. I went through the setup guide and got everything tuned correctly, and when I plug mics in I get sound. So far so good.

I am encountering two issues:

• The LED is red with signal and green as it approaches clip which is backwards. According to the docs it should be the other way around, green with signal, and red clip/saturated
• I hear some noise in the signal. I only hear the noise when there is a mic plugged in (even a condenser without phantom power), and it gets louder when I turn either gain stage up.

I have double checked all the caps and diodes to make sure they are oriented correctly. I tried taking the DI out/replacing JP3 and there is no change in behavior.

Anyone have any ideas how I can diagnose from here for either of these issues?

Thank you!

[JPK]

1. Reverse the direction of the LED.
2. check that the caps that have provision for 2 sizes (2.5 or 5mm) are placed in the right holes.

[mungu]

Thanks JPK - will try that and let you know what happens!

[mungu]

Alright - the LED issue is fixed, but no luck with the noise.

I checked all the 2.5mm film caps and the appear to be in the right location. I wasn't quite sure which is the correct 2 pins to use, but my position does match the image in the assembly guide. I attached pictures just in case it is obviously wrong for some reason?

I reflowed all the joints for the film caps just in case. Doesn't seem to have had any effect.

Any more ideas for what I can look at?

[mungu]

Pic for the other set of 2.5mm caps too

[mungu]

Update: this weekend I re-flowed all the joints on the electrolytic capacitors and it seems to have fixed the problem! Everything is working great now.

Now on to build my 2nd one.

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