Very different sensitivity on 1V and 2V range, 2203

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Very different sensitivity on 1V and 2V range, 2203

Post by G-son »

I got a second hand 2203 a while back, for the most part it works very well with Pico 6. The one issue I have is that it seems to have very different sensitivity for short voltage spikes when I change between 1V (or less) and 2V (or more) ranges, and that's also the change when I hear a relay inside the unit click. Both channels react the same way.

Here's a secondary ignition waveform (spark in open air, not on engine), attenuated so it is a bit over 1V when viewed @ 1V range (I want to keep it far away from voltages that may damage the scope). However, when I change to the 2V range to see the entire peak the wave form suddenly shrinks to more like 0.5V peak.
For anything slower the scope seems to keep up and show what it's supposed to on all ranges, but the sudden inductive spikes such as from ignition coils, relay coils and such doesn't show well on 2V range or higher.
Secondary 2V.jpg
secondary 1v.jpg
Is there anything I can do to get around this issue? Is the scope damaged @ the higher ranges or is this as good as it gets in the low price scope? Being second hand I unfortunately don't know the history of the unit, and it's a few years old now too.

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