After watching a youtube video about how to use an oscilloscope by sparkfun, I switched all probes and channels to 10x and adjusted the trim caps in the probes against the built in test signal to make the square wave look square.
With gnd ref on the cpu gnd pin 20 instead of chassis gnd, and a couple probes on X1 and reset_in, and one probe on chassis ground, now the x1 and reset_in signals are steady, reset_in looks flatter, and only the trace for chassis ground floats and bobs up and down now. So chassis ground simply floats around in relation to the rest of the board, or at least in relation to the cpu. Not a bad afe in the scope. *chagrin* -- bkw On Dec 6, 2017 7:38 PM, "Brian White" <[email protected]> wrote: > This is the bobbing I was talking about. It's dumb for me to even be > talking about it yet since I haven't even done a basic comparison check on > some other reference yet. > > https://youtu.be/b9jAYsfTOzQ > > And here's another look at a different signal hooked up a different way. > Here, I have the ground ref hooked to the gnd pin 20 on the 8085, NOT the > chassis ground. And CH4 is on pin 18, AD6. The offsets, trigger, and > vertical scales are all visible on-screen. > > https://photos.app.goo.gl/mel4CKym2EtcV1352 > > https://photos.app.goo.gl/K1AIj3Pmt15xXfR72 > > > -- > bkw > >
