reception problem after CPU replacement

[DexterSdj]

Hi all guys,

I have been the owner of a "(tr)uSDX" for more than a year and like everyone else the first thing I did was adjust the filters to have acceptable efficiency, but unfortunately during the adjustment I killed the CPU; at that time I had a Chinese Arduino where I extracted the CPU and installed it in the (tr)uSDX but I realized that the serial number was "58FFDFFFDFFFFFFFFF" and following the forum I understood that it was a counterfeit chip; but the radio worked (and well too) and therefore I didn't give much weight to this defect. But now the time had come to install the latest software and so I ordered the new CPU from "Reichelt"; I installed the bootloader and the software, the radio turns on as normal, but now the RX doesn't receive anything (no hiss). after having probed with an oscilloscope I find that si5351 works as it should. so I try it under a dummy load and I realize that the TX also works but a little distorted. the last components left to test are "lt6231" and "SN74CBT3253" on the screen the meter displays a fixed -54dbm and if I place my fingers on the CPU pins "pc1" and "pc0" I can hear discharges from the speaker and the meter reacts . so I feel like excluding the CPU....I also checked with a meter the presence of some cold soldering, but nothing. Do you have any advice on how to proceed?

I apologize for my English but I am using the translator so if something is not clear please write to me.

I take this opportunity to thank the creators of this fantastic project (Mr. Manuel and Mr. Guido) who helped me get closer to this world of amateur radio where I learned a lot. Thank you so much guys. and thanks to anyone who will help me in this misadventure.
With best regards
Marco Di Mattia.
73 everyone!

[dl6sez]

Hello OM Marco,

please take care of ESD... fingers on a CPU when you are not working on an EPA can easily kill it....
if you have an oscilloscope you can even test the signal output of LT6231 look tuned to for example 10.100,8 khz DWD DDK9 Weather RTTY, for 90° difference of the output signals.
If there are none, it can be LT6231 or 74cbt3253 or RX mute FET Q1.
Hope you find it fast

73 de Chris