Ok, this is the last experiment, now you must be able to see it !!jye1 wrote:Thank you. But the link couldn't be opened either.
This is a chinese server.
I checked the voltage on oscilloscope screen with a 3.3v bus pirate DC source and It was ok!jye1 wrote:Thank you! I saw the video finally. For the issue I'd suggest you first check the scope with some DC source of known voltage (like a battery or regulated power supply). This is to verify that the gain/attenuation of analog channel is correct. If the gain is correct then reproduce the issue. Touch connectors, slide switches (the upper two) to see if there is connection problem. You can also measure the DC voltage of test signal with a multimeter. The reading should be around 2.5V. If you get value lower then it could be the test signal problem.
The amplitude of 1KHz signal for bus pirate is 3.3V and it matches!jye1 wrote:Do you know the amplitude of 1KHz signal for bus pirate? If it matches the scope reading then scope is good. The amplitude of test signal could be wrong.
You can see the correct amplitude of signal measured on second line of multimeter. Please do more attention to upper picture!You have checked the frequency of test signal. But correct frequency doesn't mean the amplitude is correct.
I did what you tell me and all gone well for 45-60 seconds, but after... the signal gone down.jye1 wrote:Sorry, I hadn't enlarge the photo and thought that was a frequency meter.
Does the voltage reading change if the meter is connected to the signal long time? I ask this question because, from the video, the signal was normal at beginning.
Otherwise, If scope is good and signal is good then the problem must be the probe. You can verify by connecting the test signal to scope input directly with a short wire. Just solder it right on the pads.