Re: TDS 380 won't trigger

Gary Appel

Some additional information.

Along with an error in level there is a positive offset of around two divisions.

The 'scope will trigger only on line.

At low sample speeds where the trace sweeps across the screen I can see a 10 Hz square wave. When I speed up the sample rate and trigger on line, it occasionally captures the input waveform, but mostly clips in the positive direction, with a clipping warning on the screen. I believe these positive values are independent of what range I am on.

I did check the supply voltages to the main board, all are okay.

Thanks for any thoughts,

Gary Appel

On Sat, 23 Jun 2018 at 03:36 Gary Appel <garyappel@...> wrote:

My TDS-380 quit triggering today, along with some other odd behavior. It
appears to still collect data and display it - if I set the sweep slow
enough to have the trace sweep across the screen, I can see a low frequency
square wave. But with a 100 mV ptop input, the TDS-380 reads more like 65
mV ptop. My immediate suspicion, without looking any further, is that the
Dallas chip has failed - accounting for the calibration error. Has anyone
had experience with a failed Dallas chip? Might it cause the trigger to

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