The first couple of pictures showing the probe calibration square wave with some fuzz on it looks pretty normal if a source of HF noise is nearby. The width of the fuzz will change by moving the probe cables around, and engaging the BW limiter should clean it up.
You report that the trace "disappears" if you switch coupling to GND. This suggests that "Normal" trigger mode is selected. Switch to "Auto" which should produce a flat trace when the input is grounded. Is this trace clean and sharp? Then disconnect the probes and switch coupling to DC. Is this trace clean and sharp, just a little fuzzy, or really noisy?
When the probes are connected to the scope, but the tips are not connected to anything, and the input is AC or DC coupled, you may see all manner of noise, dominated mostly by your mains frequency as David mentioned earlier. This is not particularly indicative of anything other than normal behaviour.
Think about trying another signal source, even if it's just a bread-boarded oscillator. And if another scope is handy, check your function generator output.
-- Mark
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--- In TekScopes@..., "rebelliouszombie" <santosismael@...> wrote:
No, the noise doesn't go away when I engage the bandwidth limiter.
Yes, the noise goes away when I disconnect the probes and set coupling to GND.
In AC coupling, when the probes are connected to the oscilloscope but the tips are not connected to anything, there is a trace on the display. It looks like a ripple, almost sinusoidal. When I switch to GND coupling, the trace disappears. When I switch to DC coupling, the trace reappears.
--- In TekScopes@..., "japh61" <japh61@> wrote:
Does the noise go away if you engage the bandwidth limiter (pull out the "Trig View" button)? Does it go away if you disconnect the probes and set the coupling to GND? If so, then you're just picking up high-frequency hash though the probes, which is not uncommon.
-- Mark
