Resistance between tip and ring on most inputs

[mackanov]

Only that almost anything here in Brazil has a risk of being counterfeit, but I don't think that in this particular case they are. Also, if they are I'd expect all inputs to behave like this, not just 24.

Should I get resistance between VCC and ground? There are those 2 capacitors there but I don't know if they have resistance as well.

[dmitri]

You really would want to check resistance between any suspected points and judging from the schematics try to figure out where might be a problem. Excessive flux, bad soldering, hair thin shorts breaks are the most common sources of DIY electrical problems.

[mackanov]

I will re-etch the analog board more carefully and try again, it's just too hard to try to solve to be worth it. I'll post my results as soon as it's done. Thanks a lot Dmitri!

[mackanov]

I designed an analog board for the 4851 ICs using Dmitri's as a starting point. Haven't got the 4851s though, very hard to find them here. So what I did was, I put the old 4051 ICs on it, to test the board, knowing that it would cause me to have crosstalks between all channels on the same mux. Suprise: It works flawlessly. All I have to do now is set up my build and play away!

Any thoughts on why my 4051s work without diodes or resistors?

If anyone needs the analog board for the 4851 ICs (and Dmitri allows it) I can share my design.

Thank you very much Dmitri for all the help and work you've put in this!

[mackanov]

Apparently my pads are too "cold". When directly hitting the transducer 4051 behaves as expected. Maybe when I do the proper pads it'll become worse, but by then I might have gotten the 4851s.