Display problem?

[cszam]

Hello everyone,
first of all, I'm a beginner with the PICO Scopes.
But I have a representation that I cannot explain. I measure a simple peak which is on all scaling
displayed correctly, except in the setting "1V", where a sharp drop to 0.6V can be seen.

I already have the help file through, so anyone has an idea how to explain it?

PICO 2205A
Probe to 10x
Latest software Picoscope

See pictures.
Left = representation at 2V (and all other Voltage settings)
Right = representation at 1V ???

Geetings cszam

[Gerry]

Hi cszam,

It appears that you could have a faulty PicoScope, but just to be sure, could you confirm that the 2 displayed captures for the ±1V and ±2V input ranges, were done with exactly the same probe and connection points on the item being measured (DUT) in a reply, and post an image showing the probe tip at the meaurement point.

Regards,

Gerry

[Gilbert]

You should also check probe compensation, probably attach a picture of what the waveform looks like for the square wave output on the front panel. Probably not the case though as you would most likely see the same thing on both scaling levels, the point being is that you should always check probe compensation as good practice. I mention this because the one probe I checked that came with our picoscope was over-compensated for low frequency response and looked like your waveform. In my case, I didn't adjust it, I just switched to one of our Tektronix probes.

[Gerry]

Hi Gilbert,

I did think of that, but as you say, I would have expected a half height equivalent decay on the 2V Input Range if it was Probe Compensation.

Regards,

Gerry

[Gerry]

Hi cszam,

If the device is at fault, then we suspect that this could be something like a 1V to 2V relay switch issue in which case we would urge you to send an email to us at support@picotech.com so that we can start the returns process, in order to get the device into the hands of our Test and Repair team.

However, just in case it is because of user error, could you confirm that you used the same probe when performing the measurements for the 2 images you posted (so that we can rule out one of the Probes being under compensated, as Gilbert mentioned) and so that we can be sure that it it's not related to how you're using the Probe, could you repeat the measurements, and show us an image of how you're probing the DUT connection points (i.e. so that we can rule out a connection issue).

Regards,

Gerry